Stable and Monochromatic All-Inorganic Halide Perovskite Assisted by Hollow Carbon Nitride Nanosphere for Ratiometric Electrochemiluminescence Bioanalysis

Article abstract of DOI:10.1021/acs.analchem.0c00070

Lead halide perovskites have been promising electrochemiluminescence (ECL) candidates because of their excellent photophysical attributes, but their poor stability has severely restricted ECL applications. Herein, the in situ assembly of all-inorganic perovskite CsPbBr₃ nanocrystals (CPB) into hollow graphitic carbon nitride nanospheres (HCNS) were described as a novel ECL emitter. The architecture guaranteed not only improved stability because of the peripheral HCNS protecting shell but also high-performance ECL of CPB because of a matching band-edge arrangement. Dual-ECL readouts were obtained from the nanocomposite including an anodic ECL from CPB and a cathodic ECL from HCNS. The former displayed prominent color purity to construct an efficient ECL resonance energy transfer system, and the latter served as an internal standard for a ratiometric analysis. A well-designed DNA probe was further utilized for the targeting of CD44 receptors on the MCF-7 cell surface and the double signal amplification. The sensing strategy exhibited good analytical performance for MCF-7 cells, ranging from 1.0 × 10³ to 3.2 × 10⁵ cells mL^-1 with a detection limit of 320 cells mL^-1. Sensitive and accurate evaluation of CD44 expression was finally achieved at 0.22 pM. This work is the first attempt to use halide perovskite for reliable ECL bioanalysis and provides a perspective to design a perovskite-based nanocomposite as a high-performance ECL emitter for its exclusive ECL system.

Full text of DOI:10.1021/acs.analchem.0c00070

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Article
Stable and Monochromatic All-Inorganic Halide Perovskite
Assisted by Hollow Carbon Nitride Nanosphere for
Ratiometric Electrochemiluminescence Bioanalysis
Yue Cao, Wenlei Zhu, Huifang Wei, Cheng Ma, Yuehe Lin, and Jun-Jie Zhu
Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.0c00070 • Publication Date (Web): 12 Feb 2020
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Stable and Monochromatic All-Inorganic Halide
Perovskite Assisted by Hollow Carbon Nitride
Nanosphere for Ratiometric Electrochemiluminescence
Bioanalysis
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Yue Caoa‡, Wenlei Zhub‡, Huifang Weia, Cheng Maa*, Yuehe Linb*, and Jun-Jie
Zhua*
aState Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry
and Chemical Engineering, Nanjing University, Nanjing 210023, PR China
bSchool of Mechanical and Materials Engineering, Washington State University,
Pullman, WA 99164, USA
ABSTRACT
Lead halide perovskites have been promising electrochemiluminescence (ECL)
candidates owing to their excellent photophysical attributes, but their poor stability
severely restricted the ECL applications. Herein, the in-situ assembly of all-inorganic
perovskite CsPbBr3 nanocrystals (CPB) into hollow graphitic carbon nitride
nanospheres (HCNS) were described as a novel ECL emitter. The architecture
guaranteed not only improved stability because of the peripheral HCNS protecting shell,
but also high-performance ECL of CPB due to a matching band-edge arrangement.
Dual-ECL readouts were obtained from the nanocomposite including an anodic ECL
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from CPB and a cathodic ECL from HCNS. The former displayed prominent color
purity to construct an efficient ECL resonance energy transfer system, and the latter
served as an internal standard for a ratiometric analysis. A well-designed DNA probe
was further utilized for the target of CD44 receptors on MCF-7 cell surface and the
double signal amplification. The sensing strategy exhibited good analytical
performance for MCF-7 cells, ranging from 1.0×103 to 3.2×105 cells mL-1 with a
detection limit of 320 cells mL-1. Sensitive and accurate evaluation of CD44 expression
was finally achieved at 0.22 pM. This work is the first attempt of halide perovskite for
reliable ECL bioanalysis and provides a perspective to design perovskite-based
nanocomposite as a high-performance ECL emitter for its exclusive ECL system.
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INTRODUCTION
Halide perovskite nanocrystals have emerged as a new class of solution-
processable semiconductors with unique optical and electrical properties, leading to
broad applications such as photodetectors,1 solar cells,2 lasers,3 light-emitting diodes.4
Given their excellent optical properties with intense emission, facile wavelength
tunability, and narrow line width,4-7 halide perovskites have shown considerable
potential in electrochemiluminescence (ECL) domain. During the last three years, ECL
phenomena of all kinds of perovskites, including all-inorganic or organic-inorganic
hybrid lead halide perovskites, and bismuth-based halide perovskite, have been
successively discovered.8-10 However, due to the high affinity of perovskites to water,
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anhydrous organic media is a prerequisite for most of such works.8,10 Moreover,
perovskites, despite their appealing ECL attributes, exhibit inherent vulnerability to
moisture, oxygen, and light exposure,11,12 which greatly limits their brilliance in normal
ECL applications.
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To slow down the degradation of perovskites, embedding them into some inert
matrixes, such as polymers,13 mesoporous silica,11 amorphous alumina,12 is one of the
most direct approaches. Significantly though their stability is improved, the wrapping
behaviors sometimes sacrifice the optical and electrical properties, particularly having
a negative effect on the electrically excited ECL. Consequently, it is highly desired to
develop a multifunctional shelter for perovskites with both protection and enhancement
effects. Of note, graphitic carbon nitride (CN) composed of N-bridged tri-s-triazine
repeating units is inert enough to resist chemical and environmental attacks.14 Here,
triple-functional hollow CN nanospheres (HCNS) are ideal scaffolds for the in-situ
assembly of perovskites, maintaining the separation of interior and exterior
environments. They provide not only a reliable shell to protect the perovskites from
external invasion, but also an internal platform with a matched band-edge to enhance
the perovskites ECL. Furthermore, the auxiliary ECL of HCNS can be used as an
internal standard for accurate self-calibrated results in complex environments. To the
best of our knowledge, reliable perovskite-related ECL application has not been
achieved so far, especially in aqueous assays.
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ECL resonance energy transfer (RET) by leveraging of overlapped spectra of donor
ECL emission and acceptor absorption has drawn considerable attention in the
analytical realm, owing to the advantages such as free of scattering light, high
sensitivity, and low cost.15,16 However, the challenge still exists to find a well-
superimposed donor-acceptor pair. For instance, the common donor of ruthenium
derivative exhibited a broad ECL full width at half maximum (fwhm) of ~100 nm,15,17
defiantly hampering the RET efficiency. Known for excellence in photoluminescence
(PL) fwhm of 12-25 nm,18 CsPbBr3 nanocrystals (CPB) are likely to be the perfect ECL
donors with high color purity, ensuring high ECL-RET efficiency. Besides, the facile
band tunability of CPB by halogen exchange facilitates the search for available ECL
receptors.19,20 Thus, it is meaningful to make full use of this superiority to construct a
perovskite-based ECL-RET system.
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Herein, the CPB-HCNS nanocomposite was synthesized through in-situ growth of
CPB within the mesoporous shell of HCNS, displaying improved stability and efficient
solid-state ECL. CD44, a promising marker for cancer, is overexpressed in many
tumors, and direct investigation of CD44 at cell level is significant to understand its
underlying natures for clinical diagnosis and research.21,22 As shown in Scheme 1, a
DNA probe was designed containing hyaluronic acid (HA) moiety, dsDNA cutting site
for endonuclease, ssDNA fragment for capturing, and primer for hybridization chain
reaction (HCR). This probe was first targeted to MCF-7 cells surface via HA-CD44
specific high-affinity. Then, endonuclease released the DNA part of probes, which
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subsequently triggered the HCR to generate long DNA duplexes for the intercalation of
rhodamine 6G (Rh6G).23,24 The resultant products were captured on the electrode
surface that was pre-modified with the CPB-HCNS nanocomposite, resulting in a
dramatically quenched anodic ECL of CPB. Further using the constant cathodic ECL
of HCNS as an internal standard, a ratiometric ECL sensing strategy was proposed for
accurate and sensitive evaluation of CD44 expression on the cell surface. This work
makes full use of the unique monochromatic ECL of CPB, which provides a new idea
for the future development of more perovskite-related ECL applications.
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Scheme 1. Schematic illustration of the entire analysis process.
EXPERIMENTAL SECTION
Synthesis of HCNS
HCNS were synthesized using a silica template according to previous work with
minor modifications.25 The silica templates with the architecture of a dense core and a
thin mesoporous shell were prepared via a classical Stöber method (Supporting
Information). Typically, 1.0 g of the silica templates were dispersed in 5.0 mL of
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cyanamide aqueous solution (50 wt%). In order to enrich monomers in SiO2 templates,
the mixture was ultrasonicated in vacuum at 40 °C for 3 h and vigorously stirring at 60
°C for 8 h. The centrifugal solids were dried in a natural environment and then
calcinated at 550 °C for 4 h under a nitrogen atmosphere with a heating rate of 4.4 °C
min-1. The obtained solids were further etched with NH4HF2 (4 M) overnight to remove
the SiO2 matrix. After centrifugation and washing with distilled water three times and
ethanol once, the yellow powders were dried in vacuum at 60 °C for 10 h to obtain the
final HCNS products.
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Synthesis of CPB and CPB-HCNS
The precursor solution was first prepared by mixing Cs2CO3 (0.2035 g), 1-
octadecene (ODE, 10 mL), and oleic acid (OA, 0.625 mL), which was dried in vacuum
at 100 °C for 1 h and then heated at 150 °C under nitrogen atmosphere until the
transparent solution formed. Then, PbBr2 (0.138 g) and ODE (10.0 mL) were loaded in
a 3-necked flask and dried in vacuum at 100 °C for 1 h. After further addition of pre-
dried oleylamine (OAm, 1.0 mL) and OA (1.0 mL), the mixture was degassed at 120 °C
for 40 min and heated to 150 °C under a stream of nitrogen. Then, 1.0 mL of the
precursor solution was quickly injected into the reaction solution, which was cooled
with an ice-water bath after 5 s. After centrifugation at 8000 rpm for 10 min, the solids
were washed with ethyl acetate (EAC) once and toluene twice. The final products were
redispersed in toluene. For the preparation of the CPB-HCNS nanocomposite, the
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HCNS/ODE solution replaced the original ODE, and the resultant products were
centrifuged at 3000 rpm for 8 min.
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Preparation of DNA Probe
Equimolar amounts of linking DNA (L-DNA) and functional DNA (F-DNA) were
mixed in a TE buffer and incubated at 37 °C for 4 h. Then, the above mixture was added
with HA (0.5 μM), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC; 5 mM),
and N-hydroxysuccinimide (NHS; 1 mM), and placed in a thermostat vibrator at 37 °C
for 5 h (Figure S1, Supporting Information). By using a filter tube (3 kD), unreacted
components were removed after centrifugation three times. The purified DNA probe
was finally gathered and redispersed in TE buffer.
Profiling of Cells Surface CD44
MCF-7 cells were incubated with 0.5 μM of DNA probe in an incubator (37 °C)
for 1 h, and then centrifuged three times at 1000 rpm for 5 min to eliminate untargeted
DNA probe. Afterward, restriction endonuclease DraI (200 U mL-1) was utilized to
specifically cleave the binding DNA probe in a thermostat shaker (37 °C) for 75 min.
After centrifugation at 2000 rpm for 5 min, the supernatant was collected and then
added with hairpin DNAs of H1 and H2 (2.0 μM) to trigger the HCR reaction at 37 °C
for 50 min. Finally, 2.0 mM of Rh6G interacted with the generated dsDNA for 1 h at
room temperature.
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Preparation of Sensing Platform and ECL-RET Determination
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Glassy carbon electrode (GCE) was pretreated following the general method, and
the freshly cleaned GCE was dropped with 10 μL of the prepared the CPB-HCNS
toluene dispersion. After drying naturally, a solid-state film was self-assembled on the
electrode surface. Tris-(2-carboxyethyl)-phosphine (TCEP; 100 mM) was used to
pretreat the capture DNA (C-DNA) to break the S-S bonds. Then, 10.0 μL of capturing
DNA (2.0 μM) was employed to functionalize the solid film, and 10.0 μL of 6-
mercapto-1-hexanol (MCH; 2.0 μM) was subsequently used to block the remaining
active sites. The sensing electrode was obtained after rinsing with distilled water and
drying in a nitrogen atmosphere. Then, 10.0 μL of the above Rh6G-dsDNA solution
was incubated with the sensing platform for 30 min. After washing with distilled water,
the electrode was used to output ECL signal with a counter electrode (Pt wire) and a
reference electrode (saturated calomel electrode, SCE) in phosphate buffer solution
(PBS, pH=7.4) containing 1 mM ascorbic acid (AA).
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RESULTS AND DISCUSSION
Morphological Investigations
Scanning electron microscopy (SEM) image of HCNS shows uniform and
monodisperse polymer nanospheres with a rough surface (Figure 1A), and transmission
electron microscopy (TEM) image displays the hollow nanostructure with a diameter
of ~390 nm and a shell of ~75 nm (Figure 1B). After CPB grew in situ within HCNS,
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a number of newly generated nanocrystals can be observed inside the HCNS (Figure
1C). And high-resolution TEM (HRTEM) captures the lattice distance of 0.29 nm in
these nanocrystals, which is consistent with the (200) plane spacing of cubic CPB.8
Besides, the elemental mapping images indicate the coexistence of Cs, Pb and Br
elements in the inner side of HCNS, mainly inside the mesoporous shell (Figure 1D).
These results suggest the successful construction of the CPB-HCNS by the proposed
in-situ growth approach.
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Figure 1. (A) SEM and (B) TEM images of the HCNS, (C) TEM image of the CPB-
HCNS and HRTEM image of the assembled CPB (inserted), (D) Elemental mapping
images of the CPB-HCNS.
Characterization of Chemical and Crystal Structures
Various techniques were used to access the chemical component of the CPB-HCNS
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nanocomposite. The survey X-ray photoelectron spectroscopy (XPS) spectrum reveals
the content of each element in the CPB-HCNS (Figure 2A). In detail, three simulated
peaks at 288.1, 285.5, and 284.6 eV in C 1s spectrum (Figure S2a, Supporting
Information) arise from N-C=N in triazine rings, C-NHx on the edges of heptazine units,
and C-C of exotic hydrocarbons,26 respectively. Also, three splitting peaks at 398.7,
399.4, and 400.6 eV in N 1s spectrum (Figure S2b, Supporting Information) indicate
the appearance of sp2-bonded N (C=N-C) in triazine rings, tertiary N in N-(C)3, and
amino N (NHx), respectively.26 These results involving C and N elements derive from
extensive triazine moieties and abundant surface amino groups of HCNS. Cs 3d and Pb
4f spectra in Figure S2c-d (Supporting Information) show four peaks at 738.3, 724.3,
142.9, and 138.0 eV, which are attributed to Cs 3d3/2, Cs 3d5/2, Pb 4f5/2, and Pb 4f7/2,
respectively.14 Also, binding energies at 67.9 and 69.0 eV in the Br 3d spectrum are
assigned to Br 3d5/2 and Br 3d3/2.14,26 The Cs/Pb/Br elements ratio of 1:1:3 in the CPB-
HCNS confirms the successful formation of CsPbBr3 nanocrystals inside HCNS (Table
S2, Supporting Information).
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Figure 2. (A) XPS full-scan spectrum, (B) XRD patterns, (C) FTIR spectra, (D), N2
adsorption-desorption isotherms and the pore size distributions (inset), (E) PL emission
spectra, (F) PL decay curves of the as-prepared HCNS (blue), CPB (green), and CPB-
HCNS (red) or some of them.
In Figure 2B, the X-ray diffraction (XRD) pattern of HCNS displays a dominant
peak at 28.4°, arising from the (002) reflection of a graphitic-like aromatic structure.14,26
The diffraction peaks of CPB are in good agreement with the characteristic patterns
from the standard cubic phase of CsPbBr3 (PDF#54-0752). After loading CPB in HCNS,
we observe both characteristic peaks on the spectrum, demonstrating the successful
combination of the two materials.
Flourier transform infrared (FTIR) spectroscopy was used to describe the mutual
effect between CPB and HCNS (Figure 2C). Since thick surface ligands (OA, OAm,
and ODE) were required to support the colloidal stability of CPB, their FTIR spectrum
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displays typical peaks at 2925, 2857, 1452, and 1654 cm-1, which represent the C-H
stretching and bending vibrations, and C=C stretching vibration.27 The FTIR spectrum
of HCNS shows the typical band of CN at 1000-1800 cm-1, which is associated with
vibrations of C=N and C-N in s-triazine units, demonstrating the successful
polycondensation of cyanamide.14 The broadband at 3000-3500 cm-1 suggests the
presence of abundant hydroxyl and amine groups on the HCNS.14,26 This band peak,
however, shifts to a lower wavenumber after the in-situ growth of CPB within the
HCNS, suggesting the strong coordination between these active groups and CPB.
Meanwhile, these C-H vibrations of the surface ligands are significantly suppressed,
indicating that the surface ligands are no longer required. Therefore, HCNS may
provide a suitable microenvironment for CPB landing because their functional groups
of amine and carboxyl work as natural stabilizers for CPB.
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HCNS display a high specific area including the inner and outer surface, as well as
mesoporous pores in the shell layers. The Brunauer-Emmett-Teller (BET) surface area
of HCNS (52.9 m2 g-1) is much higher than that of previously reported bulk CN (8.9 m2
g-1).26 After the formation the nanocomposite, the BET surface area decreases to 32 m2
g-1, and the pores with size of 20-50 nm almost disappear (Figure 2D), demonstrating
the in-situ formation of CPB in the mesoporous layer of HCNS. Clearly, the large
surface and pores of HCNS possess abundant exposed carbon and nitrogen atoms that
translate to active amine and carboxyl groups, providing the hotbed for CPB landing.
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Characterization of Optical Properties
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The steady-state PL emission spectrum of the CPB-HCNS displays three clear
peaks (Figure 2E). The main peak at 433.0 nm and a shoulder peak at 460.3 nm belong
to HCNS. It is notable that PL intensity of HCNS is much stronger than that of bulk CN
due to its special hollow nanosphere structure, and the main peak blue-shifts obviously
because of quantum confinement effect with the reduced average size (Figure S3,
Supporting Information).28 Besides, the dominant PL emission peak at 507 nm with a
narrow spectral width of about 22 nm is attributed to CPB, suggesting the negligible
influence for the optical property of CPB by loading them into HCNS. In addition, the
exciton recombination dynamics of the samples were also studied by time-resolved PL
curve (Figure 2F). The decay curves for both CPB and CPB-HCNS are well fitted to
bi-exponential functions with average PL lifetimes of 5.58 and 7.50 ns, respectively.
The prolonged lifetime is probably related to the increasing of CPB size in the
nanocomposite because of the subdued quantum confinement and exciton binding
energy for larger particles.26 Also, the strong interaction between two semiconductors
may slow the exciton recombination rate of CPB in favor of good optical properties.29
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Stability of CPB-HCNS
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Figure 3. (A) PL evolutions of the CPB and CPB-HCNS toluene dispersion stored at
4 °C for thirty days. (B) PL photographs of the HCNS (1), CPB (2), and CPB-HCNS
(3) modified filter paper were taken every ten-day storage under ambient conditions.
(C) PL photographs were taken from the CPB-HCNS (left) and CPB (right) modified
glass substrates that were immersed in distilled water for 8 h. (D) ECL evolutions of
the CPB and CPB-HCNS modified GCEs that were immersed in distilled water for
twelve hours.
To employ perovskite nanocrystals for aqueous ECL applications, the stability is
of paramount importance. The storage stability was first evaluated by recording the PL
changes of samples, which were stored in toluene dispersion with capped reagent
bottles at 4 °C. As shown in Figure 3A, the CPB-HCNS remained approximately 71%
of the initial PL intensity even after thirty-day storage, whereas the PL of CPB declined
rapidly, leaving only about 8% of the initial one. The detailed PL spectra changes were
supplied in Figure S4 (Supporting Information). Next, the samples of HCNS, CPB and
CPB-HCNS were dropped into areas marked as “1, 2, 3” on the filter paper, respectively,
and placed under ambient conditions to test their air stability. Three weeks later, the
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CPB-HCNS were still able to emit a strong PL, while PL of CPB considerably
diminished, indicating the greatly improved air stability of the CPB-HCNS (Figure 3B).
Water stability directly determines the feasibility of aqueous ECL application of the
perovskite, which was examined by immersing films of CPB-HCNS and CPB on glass
substrates into the water (Figure 3C). Clearly, visible PL could be observed from the
nanocomposite for more than 8 h in water. By contrast, CPB were destroyed under the
same conditions despite thick surface ligands. ECL stability was further evaluated by
immersing the CPB and CPB-HCNS modified GCEs in distilled water. As shown in
Figure 3D, CPB-HCNS maintained 90% of the initial ECL intensity after 6 h. Twelve
hours later, CPB-HCNS still remained 64% of the initial ECL intensity, but CPB have
almost no ECL response. These results demonstrated that the compact HCNS shell
effectively protected CPB from the invasion of oxygen and moisture and thus
significantly improved the stability for the following aqueous ECL experiments.
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ECL performance of CPB-HCNS
Figure 4. (A) ECL intensity-potential curves and the corresponding CV profiles of the
HCNS, CPB, and CPB-HCNS in PBS containing 1 mM AA, (B) Normalized ECL
intensity-time curves of the CPB-HCNS with various scanning ranges.
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The ECL and electrochemistry (EC) behaviors of CPB, HCNS and CPB-HCNS
were studied by drop-casting them on GCEs. CPB show a very low anodic ECL in PBS,
probably due to the coreation with dissolved oxygen or other impurities (Figure S5,
Supporting Information).10 After adding 1 mM AA in PBS, CPB exhibit an enhanced
ECL that rises from +0.72~+1.0 V continuously (Figure 4A), indicating that the
nontoxic AA serves as the efficient coreactant for CPB. Regardless of the presence of
AA in PBS, a weak cathodic ECL from -0.78~-1.2 V is emitted from HCNS, which is
consistent with the typical ECL emission of CN (Figure 4A; Figure S5, Supporting
Information).30 As for the nanocomposite, double ECL signals are observed at both
positive and negative potential in accordance with ECL overlap of CPB and HCNS in
PBS containing 1 mM AA. After removing oxygen by bubbling pure nitrogen, the
cathodic ECL of the nanocomposite almost disappeared, demonstrating the dissolved
oxygen works as the coreactant of HCNS (Figure S6, Supporting Information).
Moreover, the vanished anodic ECL of the nanocomposite in PBS further suggests the
coreation capacity of AA (Figure S5, Supporting Information). Notably, the anodic
ECL of the nanocomposite deriving from the CPB is boosted by approximately 5.9-fold,
indicating the occurrence of synergistic effect within the construction. More
importantly, the anodic maximum ECL-emitting potential of the CPB-HCNS appears
in advance relative to sole CPB, suggesting a faster charge recombination dynamic for
CPB in the nanocomposite. As shown in Figure 4B, the high scanning potential causes
a fast decayed ECL, and only the range of 0-1.0 V maintains a stable ECL. This result
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demonstrates that the decline of ECL potential of the CPB-HCNS can prevent CPB
from the decomposition at high potential. Therefore, an efficient and stable ECL signal
can be achieved from the prepared CPB-HCNS in aqueous solution.
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Figure 5. UV-vis absorption spectra and direct optical band gaps derived from the
(Ahν)2 versus hν plots of (A) CPB and (B) HCNS, (C) Valence-band XPS spectra of
CPB and HCNS, (D) Band structure of the CPB-HCNS nanocomposite.
To shed light on the possible mechanism of the upgraded ECL performance, we
analyzed the band structures of the nanocomposite. The band gaps of CPB and HCNS
were computed to be 2.40 and 2.98 eV from their respective UV-vis absorption spectra
in Figure 5, which are similar to previous reports.26,31 The valence-band XPS spectra in
Figure 5C indicates that the valence band maximum (VBM) energy levels of CPB and
HCNS were roughly estimated at +1.67 and +1.79 eV, respectively. As a result, the
band-edge configuration is schematically illustrated in Figure 5D. For the single CPB,
ECL was essentially derived from the charge recombination in the excited CPB. In the
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case of CPB-HCNS system, AA intermediate radials injected a large number of
electrons to the conduction band (CB) of HCNS shell. Then these electrons were
favorably transferred to CPB because of the much higher CB edge potential of HCNS
than that of CPB. Thus, with the assistance of HCNS shell, CPB not only obtained
sufficient electrons, but also avoided to directly contact with the external aqueous
system. In addition, holes were continuously injected into the valence band (VB) of
CPB and stayed put during the positive scanning, because the VB edge potential of
HCNS was higher than that of CPB. As a result, the sufficient excited hole-electron
pairs of CPB led to a greatly enhanced ECL and a faster recombination dynamics.
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ECL-RET Efficiency Evaluation
Figure 6. The anodic ECL spectrum of the CPB-HCNS nanocomposite (red), PL
spectrum of CPB (green), and UV-vis absorption spectrum of Rh6G (black).
To demonstrate the good monochromaticity of ECL spectrum of CPB, we
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measured the anodic ECL spectrum of the nanocomposite with a set of long-pass filters.
As shown in Figure S7A, the filtered ECL intensity at different wavelengths can be
perfectly fitted with a sigmoidal curve. After deriving this curve, the ECL spectrum was
obtained (Figure S7B). The ECL spectrum of CPB is centered at 525.7 nm with an
fwhm of 34.5 nm, displaying high color purity among the widely used ECL emitters to
the best of our knowledge (Table S3, Supporting Information). Compared with their PL
spectrum, the ECL emission redshifts ~18.7 nm and the fwhm bandwidth broadens
~12.5 nm (Figure 6). This is because ECL is closely related to the surface chemistry of
emitters. The inevitable surface defects will cause the relaxation of charge injections
(electrons and holes), thereby resulting in an expanded and red-shifted ECL emission.
We first calculated the integrated area where the normalized spectra of CPB (ECL) and
Rh6G (absorption) overlap, and then divided it by the integrated area of the entire ECL
spectrum of CPB to evaluate the ECL-RET efficiency. Owing to the remarkable ECL
monochromaticity of CPB, ECL-RET efficiency between CPB and Rh6G reaches
93.8%. In addition, the cathodic ECL spectrum of HCNS was also simulated by the
same method, exhibiting a peak wavelength at 444.6 nm with fwhm of 103.3 nm (Figure
S8, Supporting Information). Although the bandwidth is about three times wider than
that of CPB, CN has been widely utilized for various ECL-RET systems,32,33 illustrating
the great potential of monochromatic CPB in building such systems.
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Characterization of the DNA Probe
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DNA probe was prepared by assembling F-DNA onto HA with a bridge of L-DNA,
and UV-vis spectra were utilized to characterize it. As shown in Figure S9 (Supporting
Information), HA shows a polysaccharide characteristic absorption peak at 196 nm, and
L-DNA-F-DNA exhibits typical peaks of oligonucleotides at 196 and 260 nm. In the
case of DNA probe, the two absorption peaks also exist, but the corresponding
absorbance ratio of A196/A260 is between those of HA and L-DNA-F-DNA, suggesting
the combination of the two units to form DNA probe. After the targeted DNA probe
was treated with endonuclease, the cleavage product shows a decreased absorbance
ratio of A196/A260, revealing the successful abscission of HA.
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Characterization and Feasibility of the Biosensing Strategy
Figure 7. Bright-field and confocal microscopy images of MCF-7 cells with the
incubation of FAM-labelled DNA probe (a), and then treated with endonuclease (b),
HA pretreated MCF-7 cells (c), and NIH-3T3 cells (d) with the incubation of FAM-
labelled DNA probe.
The targeting process of DNA probe to living cells was verified by the laser
scanning confocal microscope. After the FAM-labelled DNA probe was incubated with
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the MCF-7 cells, a strong fluorescent (FL) signal was observed (Figure 7a). In the case
of cleavage by endonuclease, the FAM-labelled DNA fragment was released from the
cells surface, leading to a significantly decreased FL signal (Figure 7b). This result
indicates that most DNA probes were targeted to the cells surface, rather than being
endocytosed into the cells. If the MCF-7 cells were pre-treated with high concentration
of free-HA to block the surface CD44, the FL signal almost disappeared (Figure 7c).
Besides, NIH-3T3 cells with low CD44 expression were also incubated with the DNA
probe, and the corresponding PL signal was rarely observed (Figure 7d). All these
results demonstrate that the DNA probe possesses the HA moiety for the specific target
of CD44 overexpressed MCF-7 cells surface and the cutting site for subsequent release
by endonuclease.
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To validate this DNA-based strategy, the entire process was examined by
polyacrylamide gel electrophoresis (PAGE; Figure S10, Supporting Information). The
L-DNA labeled with fluorescein (L-DNA-FAM) showed the fastest migration rate in
lane 1. The single UV band in lane 2 situated at a distant place away from that of L-
DNA-FAM, indicating the successful hybridization between L-DNA-FAM and F-DNA.
The cutting process was confirmed by the UV band in lane 3 with a slightly faster
migration rate due to the loss of a small fragment of dsDNA. As regards the HCR
reaction, both monomers FAM-labeled H1 (H1-FAM) and H2 were closed in the
absence of F-DNA, displaying a single UV band of H1-FAM in lane 4 and lane 5. Upon
the introduction of F-DNA, HCR reaction was activated to form numerous long
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dsDNAs, corresponding to the broad UV band with a high molecular weight in lane 6.
These results demonstrate the feasibility of the DNA-related process in this strategy.
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The fabrication process of the ECL sensing platform was investigated by cyclic
voltammogram (Figure S11, Supporting Information). Compared with bare GCE (a),
the CPB-HCNS modified GCE displayed a decreased current response (curve b). The
current of the sensing platform was continuously declined after the modification of C-
DNA and the block of MCH (curve c and d), because the non-electrochemically active
substances hindered the electron transfer. At last, the redox current reduced to the
lowest value after the capture of HCR products (curve e), demonstrating the successful
fabrication of the ECL sensing platform.
Quantitative Determination of the CD44 Overexpressed MCF-7 Cells
Figure 8. (A) ECL intensity-potential curves of the MCF-7 cells concentrations of
3.2×102, 103, 3.2×103, 104, 3.2×104, 105, 3.2×105, 106 cells mL-1 (a-h, respectively), and
(B) corresponding standard curve for the determination of CD44 overexpressed MCF-
7 cells.
The whole analysis underwent the processes of incubation of DNA probe with cells,
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subsequent cleavage by endonuclease, HCR reaction triggered by released F-DNA, and
the capturing of dsDNA-Rh6G products on the sensing platform, whose experimental
times were optimized to be 60, 75, 50, and 30 min, respectively (Figure S12, Supporting
Information). Figure 8A presents the actual ECL-potential responses of the sensing
platform with the increasing concentration of MCF-7 cells from 3.2×102 to 1.0×106
cells mL-1 (a-h). As mentioned above, the ECL curves exhibit both anodic and cathodic
ECL signals, attributed to ECL emission of CPB and HCNS, respectively. The anodic
ECL intensity (ECLCPB) at around +0.95 V decreases obviously because of high ECL-
RET efficiency between CPB and Rh6G, whereas the cathodic ECL intensity (ECLHCNS
at around -1.10 V can be approximated as a constant value. As a result, an internal
standard method was used by analyzing the ratio of ECLCPB/ECLHCNS, which can
reduce interferences from the complex environment via self-calibration. As shown in
Figure 8B, the standard curve displays a good linear relationship between
ECLCPB/ECLHCNS and the logarithmic value of MCF-7 concentration from 1.0×103 to
3.2×105 cells mL-1 with a regression equation of ECLCPB/ECLHCNS=37.53-6.15logCcells
(cells mL-1, N=6, R2=0.992) (equation 1) and a detection limit of 320 cells mL-1.
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Evaluation of CD44 Expression on MCF-7 Cells Surface
To estimate CD44 expression on MCF-7 cells surface, the established platform was
directly utilized to sense a certain concentration of F-DNA. As displayed in Figure S13
(Supporting Information), the ratio of ECLCPB/ECLHCNS exhibits a favourable linear
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relationship with the logarithmic value of the concentration of F-DNA, and the
corresponding regression equation is ECLCPB/ECLHCNS=77.50-6.15logCDNA (copies
mL-1, N=5, R2=0.999) (equation 2) in the range of 6×109-6×1011 copies mL-1. By
integrating the above two regression equations (equation 1 and 2), the CDNA/Ccells is
calculated to be 3.2×106 copies per cell. Moreover, HA is polymerized with dual-
carbohydrate units, and each unit has a molecular weight (MW) of 379.32 and a single
carboxyl group (Figure S1, Supporting Information). Given that the used HA in this
work has an average MW of 3 kD, ~7.9 copies of F-DNA can be bonded to one of HA.
Thus, the average number of CD44 on each MCF-7 cell surface is estimated to be
4.1×105 copies per cell.
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As the detection limit of MCF-7 cells is 320 cells mL-1, as low as 0.22 pM of CD44
can be detected with the proposed ECL sensing strategy. The outstanding analytical
performance probably results from the following advantages. First, HCNS provide an
ideal shelter for in-situ assembly of CPB with greatly improved stability and ECL
properties. Second, the monochromatic ECL of CPB has a wonderful spectrum overlap
with the absorption of Rh6G, ensuring the high ECL-RET efficiency. Third, a constant
ECL signal from the HCNS serves an internal standard for accurate assay. Fourth, the
HCR reaction generates long dsDNAs for the embedding of abundant Rh6G molecules.
Finally, the DNA probe has a self-amplified function because of the molar ratio
between the HA and F-DNA moieties. In sum, the proposed strategy based on the novel
ECL emitters of CPB-HCNS realized ultrasensitive estimation of CD44 on living cell
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CONCLUSION
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In summary, the as-synthesized CPB-HCNS nanocomposite achieved notable
improvements in stability and ECL efficiency. Using this nanocomposite as an
electrode matrix, dual ECL signals were obtained at both anodic and cathodic potential,
belonging to ECL emission of CPB and HCNS, respectively. The high ECL purity of
CPB held great potential in the construction of ECL-RET system. The constant ECL of
HCNS served as the internal standard for a ratiometric strategy. DNA probe was well
designed to perform the ECL bioassay for the estimation of CD44 expression on MCF-7
cell surface. The sensing strategy can also be extended to identify other subtypes of
disease and clinical diagnosis at cell level. In view of these superiorities, this work
might provide an avenue to design high-quality perovskite-based ECL emitters for
analysis applications.
Supporting Information
Materials, instruments, synthesis of silica template, cell culture, PAGE method,
preparation of DNA probe, detailed XPS spectra and content result, ECL behaviors, PL
and ECL spectra, table for comparison of ECL fwhm, UV-vis absorption, and CV
characterizations, PAGE results, optimal experiments, and ECL-time curves are
supplied as Supporting Information. This material is available free of charge via the
Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
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Corresponding Authors
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Cheng Ma; E-mail: chengma@nju.edu.cn
Yuehe Lin; E-mail: yuehe.lin@wsu.edu
Jun-Jie Zhu; E-mail: jjzhu@nju.edu.cn
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
‡Y. Cao and W. Zhu contribute equally to this work. This work was supported by the
National Natural Science Foundation of China (Grant Nos. 21834004, 21904063 and
21427807), and the Natural Science Foundation of Jiangsu Province (Grant No.
BK20190279).
REFERENCES
(1) Li, J.; Wang, J.; Ma, J.; Shen, H.; Li, L.; Duan, X.; Li, D. Self-Trapped State Enabled
Filterless Narrowband Photodetections in 2D Layered Perovskite Single Crystals. Nat.
Commun. 2019, 10, 806.
(2) Yang, Y.; You, J. Make Perovskite Solar Cells Stable. Nature 2017, 544, 155-156.
(3) Eaton, S. W.; Lai, M.; Gibson, N. A.; Wong, A. B.; Dou, L.; Ma, J.; Wang, L. W.;
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Leone, S. R.; Yang, P. Lasing in Robust Cesium Lead Halide Perovskite Nanowires.
6
7
Proc. Natl. Acad. Sci. U. S. A. 2016, 113, 1993-1998.
8
9
10
11
12
13
14
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42
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44
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48
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52
53
54
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56
57
58
59
60
(4) Lin, K.; Xing, J.; Quan, L. N.; de Arquer, F. P. G.; Gong, X.; Lu, J.; Xie, L.; Zhao,
W.; Zhang, D.; Yan, C.; Li, W.; Liu, X.; Lu, Y.; Kirman, J.; Sargent, E. H.; Xiong, Q.;
Wei, Z. Perovskite Light-Emitting Diodes with External Quantum Efficiency
Exceeding 20 Per Cent. Nature 2018, 562, 245-248.
(5) Abdi-Jalebi, M.; Andaji-Garmaroudi, Z.; Cacovich, S.; Stavrakas, C.; Philippe, B.;
Richter, J. M.; Alsari, M.; Booker, E. P.; Hutter, E. M.; Pearson, A. J.; Lilliu, S.;
Savenije, T. J.; Rensmo, H.; Divitini, G.; Ducati, C.; Friend, R. H.; Stranks, S. D.
Maximizing and Stabilizing Luminescence from Halide Perovskites with Potassium
Passivation. Nature 2018, 555, 497-501.
(6) Liu, Y.; Zhang, Y.; Yang, Z.; Ye, H.; Feng, J.; Xu, Z.; Zhang, X.; Munir, R.; Liu,
J.; Zuo, P.; Li, Q.; Hu, M.; Meng, L.; Wang, K.; Smilgies, D.-M.; Zhao, G.; Xu, H.;
Yang, Z.; Amassian, A.; Li, J.; Zhao, K.; Liu, S. Multi-Inch Single-Crystalline
Perovskite Membrane for High-Detectivity Flexible Photosensors. Nat. Commun. 2018,
9, 5302.
(7) Stoumpos, C. C.; Kanatzidis, M. G. Halide Perovskites: Poor Man's High-
Performance Semiconductors. Adv. Mater. 2016, 28, 5778-5793.
(8) Li, L.; Zhang, Z.; Chen, Y.; Xu, Q.; Zhang, J. R.; Chen, Z.; Chen, Y.; Zhu, J. J.
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Sustainable and Self‐Enhanced Electrochemiluminescent Ternary Suprastructures
Derived from CsPbBr3 Perovskite Quantum Dots. Adv. Funct. Mater. 2019, 29,
1902533.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(9) Tan, X.; Zhang, B.; Zou, G. Electrochemistry and Electrochemiluminescence of
Organometal Halide Perovskite Nanocrystals in Aqueous Medium. J. Am. Chem. Soc.
2017, 139, 8772-8776.
(10) Cao, Y.; Zhang, Z.; Li, L.; Zhang, J. R.; Zhu, J. J. An Improved Strategy for High-
Quality Cesium Bismuth Bromine Perovskite Quantum Dots with Remarkable
Electrochemiluminescence Activities. Anal. Chem. 2019, 91, 8607-8614.
(11) Wang, H. C.; Lin, S. Y.; Tang, A. C.; Singh, B. P.; Tong, H. C.; Chen, C. Y.; Lee,
Y. C.; Tsai, T. L.; Liu, R. S. Mesoporous Silica Particles Integrated with All-Inorganic
CsPbBr3 Perovskite Quantum-Dot Nanocomposites (MP-PQDs) with High Stability
and Wide Color Gamut Used for Backlight Display. Angew. Chem. Int. Ed. 2016, 55,
7924-7929.
(12) Loiudice, A.; Saris, S.; Oveisi, E.; Alexander, D. T. L.; Buonsanti, R. CsPbBr3
QD/AlOx Inorganic Nanocomposites with Exceptional Stability in Water, Light, and
Heat. Angew. Chem. Int. Ed. 2017, 56, 10696-10701.
(13) Zhang, H.; Wang, X.; Liao, Q.; Xu, Z.; Li, H.; Zheng, L.; Fu, H. Embedding
Perovskite Nanocrystals into a Polymer Matrix for Tunable Luminescence Probes in
28
ACS Paragon Plus Environment

Page 29 of 33
Analytical Chemistry
1
2
3
4
5
Cell Imaging. Adv. Funct. Mater. 2017, 27, 1604382.
6
7
8
9
(14) Zhao, Y.; Wang, Y.; Liang, X.; Shi, H.; Wang, C.; Fan, J.; Hu, X.; Liu, E.
Enhanced Photocatalytic Activity of Ag-CsPbBr3/CN Composite for Broad Spectrum
Photocatalytic Degradation of Cephalosporin Antibiotics 7-ACA. Appl. Catal. B:
Environ. 2019, 247, 57-69.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(15) Li, Z.; Lin, Z.; Wu, X.; Chen, H.; Chai, Y.; Yuan, R. Highly Efficient
Electrochemiluminescence Resonance Energy Transfer System in One Nanostructure:
Its Application for Ultrasensitive Detection of MicroRNA in Cancer Cells. Anal. Chem.
2017, 89, 6029-6035.
(16) Chen, M. M.; Wang, Y.; Cheng, S. B.; Wen, W.; Zhang, X.; Wang, S.; Huang, W.
H. Construction of Highly Efficient Resonance Energy Transfer Platform Inside a
Nanosphere for Ultrasensitive Electrochemiluminescence Detection. Anal. Chem. 2018,
90, 5075-5081.
(17) Zhao, G.; Wang, Y.; Li, X.; Yue, Q.; Dong, X.; Du, B.; Cao, W.; Wei, Q. Dual-
Quenching Electrochemiluminescence Strategy Based on Three-Dimensional Metal-
Organic Frameworks for Ultrasensitive Detection of Amyloid-β. Anal. Chem. 2019, 91,
1989-1996.
(18) Lignos, I.; Stavrakis, S.; Nedelcu, G.; Protesescu, L.; deMello, A. J.; Kovalenko,
M. V. Synthesis of Cesium Lead Halide Perovskite Nanocrystals in a Droplet-Based
29
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