Jingfa Yang

Jingfa Yang
Chinese Academy of Sciences | CAS

About

52
Publications
4,334
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
464
Citations

Publications

Publications (52)
Article
Full-text available
There have been controversies about the binding of cations to poly(ethylene oxide) (PEO) chains in aqueous solutions. In the current study, single molecular evidence of charging PEO chains by cation binding in aqueous solutions is provided. From the adoption of the photon-counting histogram method, it is discovered that the local pH value at the vi...
Article
The activation, by residual stress, of the fast portion of rotational motion of single fluorescent probe molecules inside a polymer thin film near its glass transition temperature is studied at single molecular level. Spin-casted poly n-butyl methacrylate (PnBMA) thin films without thermal annealing are chosen as the model system and single molecul...
Article
Extracellular plaque deposits of β‐amyloid peptide(Aβ) are one of the main pathological features of Alzheimer’s disease (AD). The aggregation of Aβ42 species, especially Aβ42 oligomers, is still an active research field in AD pathogenesis. Secretory clusterin protein (sCLU), an extracellular chaperone, plays an important role in AD pathogenesis. Al...
Article
Creating densified and stable liquid is a straightforward strategy for the fabrication of strong and ultra-stable amorphous or glassy materials. The current study has discovered that a liquid polymeric thin film is densified under the application of a high frequency surface acoustic wave (SAW). The experimental evidence is the decrease in film thic...
Article
Full-text available
The diffusion of molecules and particles inside the aqueous suspension of soft colloids (polymer microgels) is investigated using variable length scale fluorescence correlation spectroscopy (VLS-FCS). Carbopol 940 is chosen as the model matrix system, and two factors affecting diffusion are investigated: the spatial hindrance and the diffusant–matr...
Article
Full-text available
Lateral diffusion of polymer molecules at the interfaces between immiscible oil and water is investigated at the single molecular level. The interfaces between water and alkanes are chosen as the model systems and polyethylene oxide (PEO) is the model polymer. Fluorescence correlation spectroscopy is used to measure the interfacial diffusion of flu...
Article
Polymer electrolytes are essential for next-generation lithium batteries because of their excellent safety record. However, low ionic conductivity is the main obstacle restricting their commercial application. Composites with nanoparticles are a promising route to overcome this obstacle. In this work, lithium polystyrene sulfonate brushes (LiPSS) i...
Article
Full-text available
A self-healing hydrogel was synthesized via the multi-component reaction of azobenzene-methacrylamide, β-CD and 3-methacrylamido phenylboronic acid. The orthogonal method was applied to analyze the influence of host–guest inclusion complexation, cross-linker and phenylboronic acid monomers content on mechanical properties and healing efficiency of...
Article
Full-text available
The physical mechanism of multiple modes in dynamics of polyelectrolyte aqueous solutions has been drawing extensive research attention for decades. This unsolved mystery makes it highly desirable to use new techniques to conduct investigations. In this study, dual-color fluorescence cross-correlation spectroscopy is applied to study the dynamics of...
Article
Full-text available
The correlation between water content and protein adsorption on the surface of polymer brushes is investigated quantitatively. Using a number of model system such as poly N-isopropylacrylamide (PNIPAM), polyethylene glycol (PEG), poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC), poly(2-hydroxyethyl methacrylate) (PHEMA), and poly (2,2,3,4,4,...
Article
In this study, we modified the well-known photothermal polydopamine nanoparticles with the poly[(2-methacryloyloxy)ethyl phosphorylcholine-b-(2-dimethylamino)ethyl methacrylate] (PMPC-b-PDMAEMA) diblock copolymers, containing both biocompatible cell membrane phosphorylcholine zwitterions segments and pH-responsive dimethylaminoethyl units on the po...
Article
Using sodium polystyrene sulfonate (NaPSS) and quarternized poly 4-vinylpyridine (QP4VP) as model systems, the chain conformation of polyelectrolytes under finite salt concentrations is investigated at a single molecular level. By fluorescence correlation spectroscopy (FCS), the hydrodynamic radius (Rh) of the samples with the molecular weight rang...
Article
Fluorescence‐based methods are promising for measuring amyloid beta (Aβ) oligomers, given their capacity to analyse a sample at the single‐molecule level. As the attachment of fluorescent labels may influence the biochemical properties of the Aβ oligomers, the effects of fluorescent labels on Aβ oligomers must be evaluated. In this paper, we compar...
Article
Full-text available
Motions of single poly(ε-caprolactone) (PCL) molecules during the formation of the dendrite crystals in ultrathin films are captured by single molecule fluorescence microscopy. The relationship of single molecule diffusion coefficient with the crystal growth rate, together with radius curvature, side-branch spacing of dendrite crystal and morpholog...
Article
Full-text available
It has long been documented that the reduced viscosity of polyelectrolyte has an anomalous dependence on its concentration, i.e., the Fuoss law. To explore the molecular mechanism, the counterion distribution of sodium polystyrenesulfonate (NaPSS) as a function of concentration is investigated at the single-molecule level. By examination of the flu...
Article
Polymers doped with photosensitive molecules/nanoparticles are believed to be promising optical data storage media. In this communication, a simple method is reported to incorporate multilayers of photosensitive molecules with controlled concentration and spatial distribution into polymer matrix. This simple hot pressing-based method makes it compa...
Article
Kinetics of the imidization reaction of poly (amic acid) (PAA) film based on pyromellitic anhydride (PMDA) and 4,4′-diaminodiphenyl ether (ODA) was studied by infrared spectroscopy. Attention is paid to the effect of solvent content inside the sample to the reaction kinetics. The results show that the presence of solvent favors the imidization reac...
Article
Full-text available
The effective charge and its evolution of single chains of DNA i-motif during its unfolding process is investigated at single molecular level. By fluorescence correlation spectroscopy and photon counting histogram, the single chain dimension and electric potential of cytosine-rich human telomeric oligonucleotides is monitored, during its unfolding...
Article
Front Cover: Self-assembly of microgels is an efficient strategy of constructing intelligent material but reversible self-assembly of microgels remains a challenge. Utilizing the light-responsive host–guest interaction between an azobenzene-nanogel and an α-cyclodextrin microgel, Ping Wang, Qiaofeng Yang, Zhipeng Ye, Chuanzhuang Zhao,* and Jingfa Y...
Article
Accessing local dynamics within a single macromolecule is the key to understand the physical origin of the viscoelasticity and especially the glass transition. In order to extract specific information on the dynamics of the branch point of a star polymer around its glass transition temperature, four-arm star poly (n-butyl methacrylate) with a fluor...
Article
Self-assembly is an efficient strategy of constructing microgel-based intelligent materials. However, it remains a challenge to realize the reversible self-assembly of microgels. Herein, a method to guide the self-assembly of soft colloids with light-stimuli is proposed, utilizing the light-responsive host–guest interaction between an azobenzene fu...
Article
A self-healing hydrogel is prepared by crosslinking acrylamide with a host–guest macro-crosslinker assembled from poly(β-cyclodextrin) nanogel and azobenzeneacrylamide. The photoisomerizable azobenzene moiety can change its binding affinity with β-cyclodextrin, therefore the crosslinking density and rheology property of the hydrogel can be tuned wi...
Article
The effect of strengthening of interaction between single fluorescent probes and polymer matrix to the probes' dynamics is investigated using single molecule fluorescence defocus microscopy. By introducing multiple hydroxyl groups to the fluorescent probes (perylene diimide derivatives) which builds up hydrogen bonds between the probe and polymer m...
Article
Lateral diffusion of cyclic polystyrene at the interface between fused silica and dichloromethane is investigated at the single-molecular level. Narrowly distributed cyclic polystyrene (c-PS) of high purity with molecular weights spanning nearly an order of magnitude is prepared via atom transfer radical polymerization (ATRP) and Cu-catalyzed azide...
Article
The molecular conformation of two typical polyelectrolytes, sodium polystyrene sulfonate (NaPSS) and quarternized poly-4-vinylpyridine (QP4VP), was studied in aqueous solutions without salt addition at the single molecular level. By fluorescence correlation spectroscopy, the hydrodynamic radius (R h) of NaPSS and QP4VP with the molecular weight ran...
Article
Lateral diffusion of diblock copolymer residing on the interfaces between two immiscible liquids is investigated at single molecular level. Fluorescence correlation spectroscopy was used to study the diffusion of fluorescence-labeled diblock copolymer, polystyrene-b-polyisoprene, at the interface formed between two immiscible liquids. The interface...
Article
Rotational motion of single fluorescence probes with different sizes doped inside films of polyvinylacetate is investigated by defocused single molecule fluorescence microscopy. Discrete vibration modes in the rotational motion of individual probes are clearly exposed in the power spectra of the rotation trajectories, reflecting multiple relaxation...
Article
As demonstrated previously (Chu X. et al, Soft Matter, 2014, 10, 5568), permanently charged polyelectrolyte brushes can experience an enhancement of swelling by exposure to external monovalent salt solution at moderate concentration. Beyond the previous static measurement, the kinetics of the swelling enhancement and de-enhancement is investigated...
Article
This study demonstrates that the conformation transition of single polymer molecules can be adjustable by applying external irradiation. By choosing poly N-isopropylacrylamide as the model system, its coil-to-globule conformation transition temperature is shifted with application of external UV irradiation, due to the photo-isomerization of the azo...
Article
Although the exact etiology and pathogenesis of Alzheimer's disease (AD) are still unclear, amyloid-β (Aβ) generated by the proteolytic processing of amyloid-β precursor protein (APP) aggregate to form toxic amyloid species. Kinesin-1 is the first identified ATP-dependent axonal transport motor protein that has been proven to affect Aβ generation a...
Article
As a typical elastic scattering technique, laser light scattering results cannot precisely describe the solution structure when the samples absorb incident light. Therefore, commercial laser light scattering instrument has been modified and upgraded to utilize four independent lasers, e. g. 785 nm, 632.8 nm, 532 nm and 457 nm, respectively as the l...
Article
The endomembrane system, including the endoplasmic reticulum, the Golgi apparatus, the lysosomes and endosomes, is located in the crowded intracellular environment. An understanding of cellular structure and functions requires knowledge of how macromolecular crowding and confinement affects the activity of membrane and its proteins. Using negativel...
Article
Thiol-terminated polymers poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC-SH), poly(N,N-isopropylacrylamide)(PNIPAM-SH) and poly(tert-Butyl acrylate) (PtBA-SH) were synthesized and the polymers were grafted on the gold surfaces of quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR) sensor chips to form brus...
Article
Full-text available
This study revisited the anti-polyelectrolyte effect of a model polyzwitterion at the single chain level and from the point of the comparison with inorganic salts and organic inner salts. A well-defined polymer of sulfobetaine was synthesized and fluorescence-labeled. Fluorescence correlation spectroscopy was adopted to probe diffusion and chain si...
Article
It has been observed previously that when permanently charged polyelectrolyte brushes are exposed to an external salt solution, they shrink when the salt level is high enough. In this study, we observed an enhanced swelling process before the salt concentration reached that limit. We systematically investigated a few strong polyelectrolyte brush sy...
Article
Rotational motion of fluorophores chemically attached to polystyrene chain-ends in ultra-thin films on solid substrates was studied by single-molecule fluorescence de-focus microscopy. The collective feature of the rotational motion was found and evidenced by the sharp change of the population of fluorophores undergoing rotational motion within a v...
Article
Full-text available
The theoretical basis of fluorescence correlation spectroscopy (FCS) for repulsive systems, such as charged colloids or macromolecules, has been further expanded and developed. It is established that the collective correlation function can no longer be fitted using the theoretical model of non-interacting systems. Also, it is discovered that the co...
Article
Effective manipulation and understanding of the dynamic responses of complex micelle nanocolloids under ac-electric fields is of great scientific and technological importance due to the emerging interest in using rich electrokinetic phenomena for medical diagnostics and drug delivery. In this work, we employ fluorescence correlation spectroscopy (F...
Article
The difference of the electric potential between the middle and end of polystyrene sulfonate (PSS-) chain is discovered experimentally. Using a pH-responsive fluorophore attached to these two locations on the PSS- chain, the local pH value was determined by single molecule fluorescence technique: photon counting histogram (PCH). By the observation...
Article
Electrostatic interaction controls the stability of charged colloidal particles dispensed in an aqueous solution. In our study, we measured the interaction between charged polystyrene particles by fluorescence cross-correlation spectroscopy (FCCS). Negative correlation function was observed for these repulsing particles and a detailed analysis by B...
Article
In-plane phase separation of polyelethylene oxide of different molecular weight has been observed. A systematic investigation on a broad range of Mw show that the process is originated from the conformatinal entropy for a polymer confined on a surface (thin film).
Conference Paper
The high sensitivity at single molecule level of fluorescence correlation spectroscopy (FCS) enables measurements of charged polymer molecules at extreme dilution condition, which has been difficulty for conventional techniques as dynamic light scattering. By FCS, the conformation transition of single chain of polyelectrolytes is clearly exposed: t...
Article
The lateral diffusion of single chain of sodium polystyrene sulfonate (PSS−Na+) on a nano-patterned surface was studied using a single molecule fluorescence method—fluorescence correlation spectroscopy. The hexagonal-patterned surface was made by the micro-phase separation of di-block copolymer, polystyrene-b-polymethyl methacrylate (PS-b-PMMA). Th...
Article
A study of the interfacial chain motion by a sensitive technique at the single molecular level , fluorescence correlation spectroscopy, was reported. The lateral diffusion of single diblock copolymer chain, polystyrene-b- polyisoprene (PS-b-PI), at the interfaces of a liquid polymer, polyisoprene (PI), with its nonsolvent, N,Ndimethylformamide (DMF...
Article
Interfacial diffusion of single chains of polystyrene-b-polyisoprene (PS-b-PI) at the interface between polyisoprene and its non-solvent, DMF, was studied by fluorescence correlation spectroscopy. The diffusion coefficient of PS-b-PI probe was found to be two orders of magnitude high than that in the bulk PI, indicating a lower interfacial viscosit...

Network

Cited By

Projects

Projects (2)