Autocatalytic Morphology Transformation Platform for Targeted Drug Accumulation

Article abstract of DOI:10.1021/jacs.8b13512

The precise and highly efficient drug delivery of nanomedicines into lesions remains a critical challenge in clinical translational research. Here, an autocatalytic morphology transformation platform is presented for improving the tumor-specific accumulation of drugs by kinetic control. The in situ reorganization of prodrug from nanoparticle to β-sheet fibrous structures for targeted accumulation is based on nucleation-based growth kinetics. During multiple administrations, the autocatalytic morphology transformation can be realized for skipping slow nucleating process and constructing the bulky nanoassembly instantaneously, which has been demonstrated to induce the cumulative effect of prodrug. Furthermore, the sustained drug release from fibrous prodrug depot in the tumor site inhibits the tumor growth efficiently. The autocatalytic morphology transformation strategy in vivo offers a novel perspective for targeted delivery strategy by introducing chemical kinetics and shows great potential in disease theranostics.

Full text of DOI:10.1021/jacs.8b13512

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Article
Autocatalytic Morphology Transformation
Platform for Targeted Drug Accumulation
Dong-Bing Cheng, Dong Wang, Yu-Juan Gao, Lei Wang, Zeng-Ying Qiao, and Hao Wang
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.8b13512 • Publication Date (Web): 25 Feb 2019
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Autocatalytic Morphology Transformation Platform for
Targeted Drug Accumulation
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Dong-Bing Cheng, Dong Wang, Yu-Juan Gao, Lei Wang, Zeng-Ying Qiao*, Hao Wang*
CAS Center for Excellence in Nanoscience, CAS Key Laboratory for Biomedical Effects of Nanomaterials and
Nanosafety, National Center for Nanoscience and Technology (NCNST), Center of Materials Science and
Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, China
Supporting Information
ABSTRACT: The precise and high-efficient drug delivery of nanomedicines into lesions remains a critical challenge in
clinical translational research. Here, autocatalytic morphology transformation platform is presented for improving the
tumor-specific accumulation of drugs by kinetic control. The in situ reorganization of prodrug from nanoparticle to β-sheet
fibrous structures for targeted accumulation bases on nucleation-based growth kinetics. During multiple administrations,
the autocatalytic morphology transformation can be realized for skipping slow nucleating process and construct the bulky
nanoassembly instantaneously, which have been demonstrated to induce the cumulative effect of prodrug. Furthermore, the
sustained drug release from fibrous prodrug depot in tumor site inhibits the tumor growth efficiently. The autocatalytic
morphology transformation strategy in vivo offers a novel perspective for targeted delivery strategy by introducing
chemical kinetics and shows great potential in disease theranostics.
bulky nanoassembly instantaneously through adding
INTRODUCTION
2
1-24
“
seeds” to skip nucleating process
.
Innovative nanoscaled drug delivery systems show
substantially potential in precision medicine and
pharmaceutical industry, but it is reported that only
~0.7% of the administered dose on average can be
accumulated in tumor site . The possible major reasons
for the inefficient accumulation are the complex tumor
microenvironment and nonspecific recognition, which
permit nanodrugs re-enter the bloodstream and
By integrating autocatalytic self-assembly into AIR
effect, we demonstrate an autocatalytic transformation
strategy wherein preformed fibrous nanodrugs in the
tumor site are served as “seed” fibrils for accelerating the
drug accumulation (Scheme 1). A peptide-based prodrug
with four moieties is developed, including (i)
hydrophobic chemodrug camptothecin (CPT), (ii)
hydrogen-bonding peptide LVFF as the scaffolds for the
formation of β-sheet structured fibers, (iii) an enzyme-
cleavable peptide GFLG, and (iv) a hydrophilic poly
1
-5
a
a
6
-8
accumulate into other organs
.
The self-assembly is pervasive and plays a critical part
in living organisms. By mimicking the natural self-
assembly systems, many smart self-assembled materials
have been developed. Recently, our group has reported
assembly/aggregation induced retention (AIR) effect in
disease sites in vivo, amplifying their sensitivity and
(
ethylene glycol) (PEG) with targeting peptide RGD
terminal. The stable as-prepared nanoparticles of CPT-
LVFFGFLG-PEG-RGD (CPT-LFPR) are intravenously (i.v.)
injected into tumor-bearing mice, which subsequently
accumulate in the tumor site based on targeting effect.
Then, in the presence of cathepsin B (CtsB), a significant
lysosomal protease overexpressed in various tumor
9
-11
specificity for disease diagnostics . Moreover, various
intracellular assembled prodrugs are reported and show
efficient anti-cancer efficacy12-14, even against drug-
(
including lung cancer, prostate cancer, and cervical
15
resistant cells . However, the artificial nanoassembly is
2
5,26
cancer)
, the nanoparticles reorganize into β-sheet
difficult to be constructed in organisms controllably due to
the chemical complexity of the in vivo environment, which
is a major challenge for in situ constructing assemblies in
specific sites. Supramolecular self-assembly via nucleation-
based mechanism has been reported in various systems,
fibrous structures due to the shedding of hydrophilic PEG-
RGD shell. The preformed fibrils in the tumor act as the
“
seeds” for accelerating the transformation of following i.v.
injected nanoparticles, which exhibit enhanced
accumulation after multiple administrations, in situ
constructing fibrous drug depot. Finally, the nanofibers
enable sustained release of free drugs inside tumor cells,
resulting in efficient inhibition of tumor growth.
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such as π-conjugated organic molecules , assemblages-
17
forming macromolecules , and β-sheet-forming peptides
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.
Usually, the kinetic behavior of nucleation-based self-
assembly is characterized by lag period of slow
a
nucleation, followed by a period of rapid growth, which
indicates the nucleation is the rate-limiting process. Thus,
an autocatalytic strategy can be used for constructing the
RESULTS AND DISCUSSION
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Scheme 1. Schematic illustration of enzyme-triggered
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morphology transformation and autocatalytic growth
of nanofibers.
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Figure 1. (A) HPLC (left) spectra of CPT-LFPR mixed with or
without CtsB in acetate buffer solution (AB, 0.01M, pH 5.0) for
1
h. MOLDI-TOF (right) spectra of CPT-LFPR (black) and HPLC
mobile phase at 35.1 min after the CPT-LFPR treated with
CtsB (red). (B) Representative TEM images of CPT-LFPR (0.5
(A) Molecular structure and self-assembly behavior of CPT-
LFPR. (B) The fibrils accelerate the subsequent
transformation into nanofibers based on autocatalytic growth
mechanism. (C) Multiple intravenous injections of
nanoparticles shows the cumulative effect of fibrous prodrugs.
-1
mg mL ) in the presence (left, PB, 0.01M, pH 7.4) of CtsB (1.0
-1
μg mL , AB, 0.01M, pH 5.0) in 10 h.
little β-sheet structure in spherical morphology (Figure 2A
and S12). Thioflavin T (ThT, a fluorescent probe) is used to
further confirm the secondary structure of the assemblies
Enzyme-triggered morphology transformation of
supramolecular prodrugs. The molecule CPT-LFPR,
control groups CPT-LVFFGGGG-PEG-RGD (enzyme non-
sensitive peptide, CPT-LGPR) and CPT-LVFFGF (nanofiber-
forming peptide, CPT-LF) are prepared by standard solid-
phase peptide synthesis and subsequent conjugation with
CPT via urethane linkage (Figure S1). The structures of
peptide-based prodrugs are confirmed by matrix-
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8
.
Interestingly, ThT can intercalate into the β-sheet
structure and exhibit fluorescence resonance energy
transfer (FRET) effect at an excitation of 375 nm with ThT
as acceptor and CPT as a donor (Figure S13), which further
demonstrates the nanofibers with β-sheet conformation
are formed. Furthermore, the Fourier transform infrared
spectroscopy (FTIR) and wide-angle X-ray scattering
(
WAXS) are performed to study the molecular packing
associated laser desorption ionization time-of-flight mass
mode in the β-sheet fibrous structure. The amide I region
1
spectrometry (MALDI-TOF-MS) and
H NMR spectra
(
Figure S2-S8).
The responsiveness of peptide GFLG under CtsB is
confirmed by high-performance liquid
first
chromatography (HPLC) and MALDI-TOF-MS (Figure 1A).
Then the enzyme-induced morphological transformation
behavior of CPT-LFPR assemblies is examined by TEM and
circular dichroism (CD). In phosphate buffer solution (PB,
0
.01M, pH 7.4), hydrophilic PEG-RGD is the crucial
segment to stabilize the CPT-LFPR nanoassemblies as
spherical structure. Transmission electron microscopy
(TEM) observation shows the CPT-LFPR disperses as
nanoparticles with 32.8 ± 4.3 nm (Figure 1B). Under CtsB,
the morphology transition of CPT-LFPR assemblies from
nanoparticles to nanofibers with the diameter of 4.5 nm is
observed by TEM in 10 h. By contrary, CPT-LGPR shows no
obvious change after the treatment of CtsB (Figure S9 and
S10). Therefore, CPT-LFPR can be cleaved by CtsB to
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generate residue CPT-LF (Figure S11), realizing the
nanoparticles-to-nanofibers morphology change.
Figure 2. (A) CD spectra of CPT-LF and CPT-LFPR treated
The driving force of transformation is first
investigated by CD spectra. After incubated with CtsB for 8
h, the CPT-LFPR assemblies show a positive CD signal at
with and without CtsB in AB (0.01M, pH 5.0). (B) FTIR spectra
-
1
-1
of CPT-LFPR and CPT-LF. The peaks at 1694 cm , 1636 cm
-
1
and 1541 cm suggest the antiparallel β-sheet conformation.
C) Wide-angle X-ray scattering (WAXS) of CPT-LF. The d-
(
1
99 nm and a negative signal at 220 nm, which confirm
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spacings of 4.7 Å and 12.2 Å are attributed to the spacing of
the adjacent strands and laminates, respectively. (D) Proposed
antiparallel β-sheet molecular arrangement of CPT-LF.
typical β-sheet fibrous structure . Nevertheless, the CPT-
LFPR shows no CD signal in the absence of CtsB, suggesting
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of FTIR spectrum at 1636 cm and 1694 cm-1 and amide II
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region peak at 1541 cm suggest the antiparallel β-sheet
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conformation (Figure 2B) of CPT-LF . There are two
distinct peaks in WAXS, in which 4.7 spacing
Å
corresponds to the distance between two adjacent strands
in β-sheet and 12.2 Å spacing is relevant to two sheets in
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the bilayers (Figure 2C). According to above analysis,
molecular arrangement model of nanofibers can be
presented (Figure 2D), and the diameter of model
nanofibers (4.3 nm) is consistent with the fibrous
structure obtained from TEM (4.5 nm). Moreover, the drug
release profiles are performed by dialysis method with or
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without CtsB. The HPLC and H NMR spectra demonstrate
the free CPT are released from CPT-LFPR in 24 h, proving
that the urethane linkage can be slowly hydrolyzed
(Figure S14).
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Figure 4. (A) TEM images and the corresponding length of
CPT-LFPR grown from fibrils. (B) Plot showing the linear
relationship of nanofiber length with mnanoparticles/mfibrils (2:1,
Kinetic analysis of autocatalytic morphology
transformation. In order to study the autocatalytic
morphology transformation, we sonicate the mature
nanofibers to obtain fibrils. In the presence of fibrils, the
distinct fibrous structure is observed at 4 h (Figure 3A),
which is faster than that without fibrils (Figure 1B).
Therefore, the fibrils can be considered as “seeds” which
speed up the morphology transition from nanoparticles to
nanofibers. The processes of autocatalytic growth are
4
:1, 6:1 and 10:1). (C) Growth profile of CPT-LFPR nanofibers
with and without fibrils monitored by ThT fluorescence in the
-1
presence of CtsB (1.0 μg mL ). Values are expressed as means
±
SD (N = 3).
nanoparticles transform into fibrous structures based on
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the fibrils
(Figure 4B). The kinetics of nanofiber
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studied by confocal laser scanning microscopy (CLSM).
formation is further analyzed by ThT fluorescence to verify
the autocatalytic growth process. The ThT fluorescence
profile without fibrils conforms to the typical kinetic curve
of nucleation-based self-assembly, showing slow
nucleation (~6 h) followed by fast autocatalytic growth
Under CtsB, the growth of CPT-LFPR fibers in the presence
of Cy5-labeled (Figure. S15) fibrils is observed (Figure 3B).
Obviously, the green nanofibers overlap with the red fibrils,
which suggest the growth of CPT-LFPR nanofibers are
initiated by preformed fibrils (Figure 3C).
(
~2 h) (Figure 4C). The data points can be well fitted by
The kinetics of autocatalytic growth are investigated
by TEM and ThT fluorescence. As shown in TEM images,
the length of nanofibers become longer with the addition
of nanoparticles (Figure 4A and S16), and the elongation of
nanofibers is proportional to the mass ratio of
nanoparticles-to-fibrils, further implying that the
the Finke-Watzky (F-W) two-step model (Figure S17),
which is commonly applied for reflecting the aggregation
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5,36
rates of nucleation-based self-assembly
. The nucleation
-4
-1
constant k and growth constant k are 2.818 × 10 min
1
2
-4
-1
-1
and 4.825 × 10 min ·μM , respectively. After addition of
fibrils, the disappearance of lag nucleation process as well
as the rapid onset of ThT fluorescence indicates the
accelerated transformation from nanoparticles to
nanofibers. Pseudo first order kinetic is applied for
describing the autocatalytic assembly and the pseudo first-
order rate constant k’ is 0.017 min , suggesting the fast
growth of nanofiber in the presence of fibrils. It is
speculated that the rapid autocatalytic growth of
nanofibers can be applied in cell and animal level for
enhancing accumulation efficiency of prodrugs.
-
1
Intracellular autocatalytic growth of nanofibers.
As above-mentioned, CtsB is overexpressed in lysosome in
most cancer cells, so the cellular uptake of CPT-LFPR
nanoparticles and their colocalization with lysosomes in
HeLa cells are monitored by CLSM. The green fluorescence
of CPT become stronger with the increase of incubation
time, which also can be colocalized with red fluorescence
from lysosomes (stained by Lysotracker red) efficiently
(Figure S18). This phenomenon suggests efficient cellular
Figure 3. (A) TEM imaging of CPT-LFPR in the presence of
-
1
37
CtsB (1.0 μg mL ) and fibrils for 4 h. Green and red arrows
endocytosis ability and lysosomal location of CPT-LFPR ,
indicate the nanoparticles and fibrils, respectively. (B) The
which meets the requirement for CtsB-triggered
schematic
illustration
of
autocatalytic
morphology
reorganization.
transformation of CPT-LFPR is first studied by Bio-TEM
Figure 5A). After incubated with CtsB-overexpressed
The
intracellular
morphology
transformation in the presence of fibrils. (C) CLSM images of
-
1
fibrils (1.0 μg mL ) and autocatalytic growth of CPT-LFPR
(
-1
nanofibers (0.5 mg mL , 24 h). White arrows indicate the red
fibrils. Scale bars: 2 μm.
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Figure 6. (A) The intracellular nanofibers monitored by ThT
fluorescence in different time points. HeLa cells are treated
with or without fibrils followed by incubation with CPT-LFPR
Figure 5. (A) Bio-TEM images of HeLa cells after incubation
with CPT-LFPR (3 μM, 12 h). (B) The corresponding energy-
dispersive profiles at the region indicated by red star in Figure 5A.
(
3 μM). Scale bar: 20 μm. (B) Fluorescent quantitative analysis
of ThT in cells.
(C) The intracellular CPT fluorescence monitored by CLSM for 4
h. HeLa cells are treated with or without fibrils followed by
incubation with CPT-LFPR or CPT-LGPR. Scale bar: 20 μm.
(Ex = 405 nm, emission windows: 500-550 nm), which
enhances with the formation of nanofibers. As shown in
Figure 6A, the yellow ThT fluorescence confirms that the
fibrils can be internalized after incubation with HeLa cells
for 1 h. Subsequently, the cells are incubated with CPT-
LFPR for 4 h, and the intensity of ThT fluorescence is
dramatically promoted (~13 folds). By contrary, CPT-LFPR
treated HeLa cells in the absence of fibrils show no
fluorescence signal change in the same time scale, and the
enhanced fluorescence is observed at 12 h. The fast
fluorescence enhancement in fibrils treated cells can be
attributed to the accelerated formation of nanofibers,
which is further verified by Bio-TEM measurement (Figure
S23). The TEM images show fast accumulation of
nanofibers in fibrils treated cells in 4 h, while there are still
nanoparticles in untreated cells. All the results prove the
autocatalytic process of nanofibers in living cells, which
may realize the improved anticancer capacity. The
cytotoxicity of LFPR, free CPT, CPT-LGPR, and CPT-LFPR
are investigated by CCK-8 assay. Figure S24 shows that
CPT-LFPR (IC50 = 4.3 μM), close to free CPT (IC50 =4.1 μM),
displays higher cytotoxic activity to HeLa cells than CPT-
LGPR (IC50 =6.8 μM). Meanwhile, the free RGD peptide can
HeLa cells, the fibrous structures are observed in CPT-
LFPR treated cells obviously, while they cannot be found in
the CPT-LGPR and CPT treated cells (Figure S19). To
confirm that the nanofibers originate from the
transformation of CPT-LFPR nanoparticles, the element
iodine is labeled onto F amino acid (Figure 5B and S20),
and energy-dispersive X-ray spectroscopy (EDS) on
intracellular fibrous structures reveals that iodine is
detected, demonstrating the formation of CPT-LF
nanofibers in cells. Flow cytometry is applied to
demonstrate the intracellular retention effect of
transformable CPT-LFPR (Figure S21). The Hela cells are
incubated with CPT-LFPR, CPT-LGPR, and CPT for 6 h, and
then the culture solutions are replaced by fresh drug-free
medium. Most of the CPT fluorescence signal intensity in
transformable CPT-LFPR treated cells remains up to 24 h.
On the contrary, the fluorescence signal disappears quickly
for CPT-LGPR and CPT treated groups. Quantitatively, the
intracellular fluorescence signal of CPT-LFPR is 3-4 folds
higher than that of CPT-LGPR and CPT at 24 h. Compared
with the CPT-LGPR nanoparticles and free drug CPT, the
higher intracellular retention of CPT-LFPR nanofibers
suggests the fibrous structure exhibits slow efflux from
cells. To verify the autocatalytic accumulation of prodrug
in cells, the fibrils are first incubated with Hela cells, and
CPT green fluorescence is observed, which demonstrates
the fibrils can be internalized in cells (Figure S22).
Subsequently, the cells are treated with CPT-LFPR for
another 4 h, and the intracellular CPT green fluorescence is
obviously stronger than the CPT-LFPR (without fibrils) and
CPT-LGPR treated HeLa cells (Figure 5C), suggesting the
higher cellular accumulation of CPT-LFPR in fibrils treated
compete for binding to the α
membrane and decrease the internalization of CPT-LFPR
nanoparticles into the α over-expressed HeLa cells,
v
β
3
integrin on the cellular
β
v 3
which result in the lower cytotoxicity. The results validate
the intracellular fibrils can accelerate the transformation
of CPT-LFPR from nanoparticles to nanofibers in cells,
which lead to the enhanced accumulation of prodrugs and
resultant highly potent inhibition ability toward tumor
cells.
Targeted accumulation of prodrugs by multiple
administration in vivo. To demonstrate the targeted
accumulation of multiple administration of CPT-LFPR, the
fresh Cy5-labeled CPT-LFPR and CPT-LGPR nanoparticles
(Figure S25) are i.v. injected into mice at day 1 and day 4.
As shown in Figure 7A, the real-time fluorescence of CPT-
LFPR in tumor at day 4 and 6 is stronger than that at day 1
and day 3, respectively. In contrast, for CPT-LGPR, there is
no obvious fluorescent change between the two injections.
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cells
.
Interestingly, FRET effect between ThT and CPT plays
vital role in marking the intracellular CPT-LFPR
a
nanofibers specifically, simultaneously eliminating
interference from intracellular proteins with β-sheet
38
structure . Thus, the intracellular autocatalytic growth of
nanofibers is investigated by FRET fluorescence from ThT
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accordance with fluorescent quantification results in vivo.
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Furthermore, the fibrous structure can be observed by bio-
TEM in tumor slices of CPT-LFPR treated mice, while not
for PBS and CPT-LGPR groups (Figure S28). Therefore, the
in situ formation of nanofibers and subsequent
autocatalytic growth cause the effective accumulation of
prodrugs, which may affect tumor growth in vivo.
The in vivo anti-tumor efficacy of peptide LFPR, free
CPT, CPT-LGPR and CPT-LFPR is studied using HeLa tumor
bearing BALB/c nude female mice. CPT-LFPR exhibits
more significant tumor inhibition efficacy than other
groups, which can be attributed to the enhanced prodrug
accumulation in tumor site through autocatalytic
morphology transformation (Figure 7E and S29). During
the treatment, there are no obvious body weight losses for
all mice groups (Figure S30), and the H&E staining shows
no apparent organ damage (Figure S31).
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CONCLUSION
In conclusion, an autocatalytic growth strategy is first
introduced into drug delivery system for targeted drug
accumulation in vivo. Considering slow nucleating and
rapid growth process of nucleation based self-assembly,
the “seed” can accelerate the formation of bulky
nanoassembly via skipping the nucleating process, which
is called an autocatalytic assembly. Through analysis of
assembly kinetics of peptide-based prodrug CPT-LFPR in
the presence of CtsB, the rate constant of autocatalytic
assembly is obviously higher than that of nucleation based
self-assembly. CPT-LFPR can instantly transform from
nanoparticles to nanofibers with the assistance of
preformed fibrils in tumor sites, which significantly
improve the drug accumulation efficacy. Compared with
the first i.v. injection, the second i.v. injection of CPT-LFPR
exhibits up to 2.4-fold drug accumulation in tumor,
implying improved cumulative effect of nanodrugs through
multiple administrations. This drug delivery system based
on autocatalytic self-assembly can suppress tumor growth
effectively. Furthermore, by introducing various imaging
agents and drugs into the autocatalytic morphology
transformation platform, we can realize improved imaging
and therapeutic efficacy of serious diseases.
Figure 7. (A) In vivo fluorescence images of tumor-bearing
mice after i.v. injection of CPT-LFPR, CPT-LGPR, and PBS at
day 1 and day 4. Red circles indicate the tumors. (B)
Fluorescent quantitative analysis in tumor at different times
(
N=3). (C) Fluorescent quantitative analysis of ex vivo tumor
and major organs at 6 d (N = 3). (D) CPT accumulation in
tumors at day 3 and day 6 after tumor-bearing mice are
injected with CPT-LFPR, CPT-LGPR and CPT at day 1 and day
4
3
, expressed as injected dose per gram of tissue (% ID/g) (N =
). (E) Tumor volume changes of mice treated with PBS, LFPR,
CPT, CPT-LGPR and CPT-LFPR (N = 5). *p <0.05, **p <0.01 and
***p <0.001.
Quantitatively, for CPT-LFPR treated group, the average
fluorescence intensity in tumor at day 4 and day 6 are 1.3-
fold and 2.3-fold higher than that at day 1 and day 3,
respectively (Figure 7B), which demonstrates the fibers
preformed after the first i.v. injection can facilitate the
accumulation of following i.v. injected CPT-LFPR. Finally,
the mice are sacrificed at day 6, and the ex vivo
fluorescence intensity of CPT-LFPR treated tumor is about
3
.9-fold higher than CPT-LGPR group (Figure 7C and S26),
which is in accordance with the quantitative result of CPT
in tumor (Figure S27), suggesting the tumor-specific
39
cumulative effect of CPT-LFPR. For further precisely
analyzing the cumulative effect of multiple administration,
CPT-LFPR, CPT-LGPR or free CPT are i.v. injected into HeLa
tumor-bearing mice with the same protocol as above
mentioned and the three groups of mice are sacrificed at
day 3 and day 6. The tumors are collected for determining
the CPT concentration by homogenization and
ASSOCIATED CONTENT
Supporting Information
1
Experimental details, H NMR, MALDI-TOF, WAXS, CD, FTIR,
CLSM, TEM, as well as the data in vitro and in vivo. This
material is available free of charge via the Internet at
http://pubs.acs.org.
40
fluorescence measurement. As shown in Figure 7D, for
free CPT, CPT- LGPR and CPT-LFPR groups, the CPT
accumulation in tumor at day 3 is 0.88%, 1.89% and 2.68%
ID/g, respectively, where the highest CPT accumulation is
detected in CPT-LFPR treated tumor. Moreover, at day 6,
the CPT accumulation in the three groups is 0.89%, 1.96%
and 6.30%, respectively. Compared with day 3, two control
groups of free CPT and CPT-LGPR show little change at day
6. While the tumor accumulation in CPT-LFPR group at day
6 is 2.4-fold higher than that at day 3, which is in
AUTHOR INFORMATION
Corresponding Author
E-mail: wanghao@nanoctr.cn (H. W.), qiaozy@nanoctr.cn (Z. Y.
Q.)
Notes
The authors declare no competing financial interests.
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(
20) Jarrett, J. T.; Lansbury Jr, P. T. Amyloid fibril formation requires
chemically discriminating nucleation event: studies of an
ACKNOWLEDGMENT
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This work was supported by National Natural Science Foundation
of China (21704020, 21374026, 31870998, 51573032 and
amyloidogenic sequence from the bacterial protein OsmB.
Biochemistry 1992, 31, 12345.
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China
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chiral components. Proc. Natl. Acad. Sci. U. S. A 1993, 90, 163.
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