Lixing Weng

Antifouling and antibacterial hydrogel coatings with self-healing properties based on a dynamic disulfide exchange reaction

Multifunctional self-healing hydrogel coatings based on a dynamic disulfide exchange reaction were developed via surface-initiated thiol–ene photopolymerization. The functional monomers (poly(ethylene glycol)methyl ether methacrylate (PEGMA), N-hydroxyethyl acrylamide (HEAA) and 2-(methacryloyloxy)ethyl trimethylammonium chloride (META)) and a disulfide-containing crosslinker bis(2-methacryloyl)oxyethyl disulfide (BMOD) were employed for the preparation of antifouling, antibacterial and self-healing hydrogel coatings. The hydrogel coatings reduced protein adsorption, as well as bacterial adhesion from Gram-negative Escherichia coli (E. coli). Moreover, the coatings exhibited good self-healing ability at moderate temperatures due to the dynamic disulfide exchange reaction. Introduction of self-healing ability provides a promising means for self-repairing of microcracks of functional polymer coatings and improving their stability and durability in the long-term applications as biomaterials.

Facile Synthesis of Yolk–Shell-Structured Triple-Hybridized Periodic Mesoporous Organosilica Nanoparticles for Biomedicine

The synthesis of mesoporous nanoparticles with controllable structure and organic groups is important for their applications. In this work, yolk-shell-structured periodic mesoporous organosilica (PMO) nanoparticles simultaneously incorporated with ethane-, thioether-, and benzene-bridged moieties are successfully synthesized. The preparation of the triple-hybridized PMOs is via a cetyltrimethylammonium bromide-directed sol-gel process using mixed bridged silsesquioxanes as precursors and a following hydrothermal treatment. The yolk-shell-structured triple-hybridized PMO nanoparticles have large surface area (320 m(2) g(-1) ), ordered mesochannels (2.5 nm), large pore volume (0.59 cm(3) g(-1) ), uniform and controllable diameter (88-380 nm), core size (22-110 nm), and shell thickness (13-45 nm). In vitro cytotoxicity, hemolysis assay, and histological studies demonstrate that the yolk-shell-structured triple-hybridized PMO nanoparticles have excellent biocompatibility. Moreover, the organic groups in the triple-hybridized PMOs endow them with an ability for covalent connection of near-infrared fluorescence dyes, a high hydrophobic drug loading capacity, and a glutathione-responsive drug release property, which make them promising candidates for applications in bioimaging and drug delivery.

Facile preparation of multicolor polymer nanoparticle bioconjugates with specific biorecognition.

A facile and efficient strategy to prepare multicolor and surface-functionalizable conjugated polymer nanoparticles (PPVseg-COOH CPNs) was demonstrated. The CPNs with tunable photoluminescence colors and carboxylate groups were further covalently modified with a series of specific molecules such as streptavidin, IgG and poly(ethylene glycol) to show their generality for subsequent bioconjugation and biological applications. The streptavidin coating can significantly improve the photostability of the PPVseg-SA CPNs, which indicates that specific biomolecules such as streptavidin functionalization of multicolor PPVseg-COOH CPNs can be applied to achieve high optical stability of CPNs in various buffer solutions, metal ions for many biological applications. Furthermore, the resulted PPVseg-SA CPNs also show efficient labeling ability in specific cellular imaging. The synthetic methods present the feasibility and versatility for further developing surface-functionalizable CPNs probes with full-color tunability for biological imaging and bioanalytical applications.

Preparation of Highly Dispersed Reduced Graphene Oxide Decorated with Chitosan Oligosaccharide as Electrode Material for Enhancing the Direct Electron Transfer of Escherichia coli

Water-dispersed reduced graphene oxide/chitosan oligosaccharide (RGO-CTSO) was prepared by chemical reduction of graphene oxide and synchronous functionalization with biocompatible chitosan oligosaccharide (CTSO). ζ potential measurement indicated that RGO-CTSO was highly stable in the acidic aqueous solution. RGO-CTSO was used to modify glassy carbon electrode (GCE) as the growth template of Escherichia coli (E. coli). The enhanced direct electron transfer of E. coli on the RGO-CTSO-modified GCE was studied by cyclic voltammetry. Compared with GCE or RGO-modified GCE, RGO-CTSO-modified GCE was more suitable for the adhesion growth of E. coli to improve direct electron transfer. The biocompatibility and versatility of RGO-CTSO made it promising for use as an anode material in microbial fuel cells.

Cisplatin and doxorubicin high-loaded nanodrug based on biocompatible thioether- and ethane-bridged hollow mesoporous organosilica nanoparticles

Herein, a mesoporous organosilica nanoparticle (MON) based nanodrug highly loaded with cisplatin (CDDP) and doxorubicin (DOX) (denoted as MONs/CDDP/DOX) has been successfully prepared for the first time. The MONs are characterized with core-contained double hollow shells, thioether and ethane groups separately incorporated frameworks, uniform diameter (420 nm), large surface area (592 m2/g), and ordered pore size (2.5 nm). The safety evaluation of the MONs based on cell viability, haemolytic activity, histological change, and serum biochemical index demonstrates that they have excellent biological compatibility. The efficient uptake of the MONs by human breast cancer MCF-7 cells is further confirmed via confocal laser scanning imaging and flow cytometry. Importantly, the contents of CDDP and DOX in the MONs/CDDP/DOX nanodrug are as high as 120 mg/g and 85 mg/g, respectively. Therefore, the MONs/CDDP/DOX shows a significant improved killing effect against human breast cancer MCF-7 cells compared with sole DOX or CDDP loaded MONs, demonstating the promise of the nanodrug for cancer treatment.

AIE-active conjugated polymer nanoparticles with red-emission for in vitro and in vivo imaging

A novel red-emission conjugated polymer (PBPTPE) with aggregation-induced emission (AIE) characteristics was developed from boron dipyrromethene (BODIPY) derivatives and 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene via palladium-catalyzed Sonogashira coupling reaction. The resulting polymer (PBPTPE) was weakly fluorescent in dichloromethane solution, but showed bright fluorescent emission when aggregated in dichloromethane/hexane mixtures or fabricated into conjugated polymer nanoparticles (PBPTPE NPs). The nanoparticles from PBPTPE were prepared through solvent-exchange method. PBPTPE NPs possess excellent photostability, including superior photobleaching resistance, and good stability in a wide pH range. Besides, in vitro cytotoxicity and hemolysis assay indicated that PBPTPE NPs had favorable biocompatibility. Furthermore, biological evaluation and bioimaging were performed using developmental stage zebrafish embryos. From the survival and hatching rate, oxidative stress and immune-related parameters, no significant adverse effect was observed. The microangiography in zebrafish, further shows that PBPTPE NPs can be used as a bioprobe for future in vivo applications.

A Novel “Off-On” Fluorescent Probe Based on Carbon Nitride Nanoribbons for the Detection of Citrate Anion and Live Cell Imaging

A novel fluorescent “off-on” probe based on carbon nitride (C3N4) nanoribbons was developed for citrate anion (C6H5O73−) detection. The fluorescence of C3N4 nanoribbons can be quenched by Cu2+ and then recovered by the addition of C6H5O73−, because the chelation between C6H5O73− and Cu2+ blocks the electron transfer between Cu2+ and C3N4 nanoribbons. The turn-on fluorescent sensor using this fluorescent “off-on” probe can detect C6H5O73− rapidly and selectively, showing a wide detection linear range (1~400 μM) and a low detection limit (0.78 μM) in aqueous solutions. Importantly, this C3N4 nanoribbon-based “off-on” probe exhibits good biocompatibility and can be used as fluorescent visualizer for exogenous C6H5O73− in HeLa cells.

Facile synthesis of yolk–shell structured monodisperse mesoporous organosilica nanoparticles by a mild alkalescent etching approach

In the work, yolk-shell structured mesoporous organosilica nanoparticles (YSMONs) are successfully prepared by a mild alkalescent etching approach. The method is very convenient, in which mesostructured organosilica nanospheres are directly transformed into yolk-shell structures after etching with mild alkalescent solution (e.g. sodium carbonate solution). The prepared YSMONs have ethane-bridged frameworks, a monodisperse diameter (320 nm), a large pore volume (1.0 cm3 g-1), a uniform mesopore (2.4 nm) and a high surface area (1327 m2 g-1). In vitro cytotoxicity and hemolysis assays demonstrate the ethane-bridged YSMONs possess excellent biocompatibility and low hemolysis activity. In addition, the YSMONs show a high loading capacity up to 181 μg mg-1 for anti-cancer drug doxorubicin (DOX). Confocal laser scanning microscopy and flow cytometry analyses show that the DOX loaded YSMONs (YSMONs-DOX) can be effiectively internalized by multidurg resistant MCF-7/MDR human breast cancer cells. The chemotherapy against MCF-7/MDR cells demonstrate that the YSMONs-DOX possess higher therapeutic efficacy compared to that of free DOX, suggesting that the YSMONs synthesized by the mild alkalescent etching method have great promise as advanced nanoplatforms for biological applications.

Polyhedral Oligomeric Silsesquioxane (POSS)-Based Cationic Conjugated Oligoelectrolyte/Porphyrin for Efficient Energy Transfer and Multiamplified Antimicrobial Activity

Cationic quaternary ammonium (QA) groups and reactive oxygen species as two main approaches for antibacterial study have been intensively studied. Herein, we report a multifunctional antimicrobial agent (porphyrin-POSS-OPVE, PPO), which combines bacterial membrane intercalation, high density of local QA groups, efficient energy transfer, significantly reduced aggregation, and high water solubility into one single molecule. The light-harvesting PPO contains multiple donor-absorbing arms (oligo( p-phenylenevinylene) electrolytes, OPVEs) on its globular periphery and a central porphyrin acceptor in the core by using three-dimensional nanocages (polyhedral oligomeric silsesquioxanes, POSSs) as bridges. The antiaggregation ability of POSS and the highly efficient energy transfer from multiple OPVE arms to porphyrin could greatly amplify singlet oxygen generation in PPO. Particularly, OPVEs with QA terminal chains were able to intercalate into Escherichia coli membranes, which facilitated 1O2 diffusion and bacterial cell membrane disintegration by QA groups. The increased local cationic QA charges in OPVE arms can also enhance the biocidal activity of PPO. Benefiting from these satisfactory features, PPO exhibits multiamplified antibacterial efficacy under a very low concentration level and white light dose (400-700 nm, 6 mW·cm-2, 5 min, 1.8 J·cm-2) to Escherichia coli (8 μM) and Staphylococcus aureus (500 nM). Therefore, PPO shows great potential for photodynamic antimicrobial chemotherapy at a much lower irradiation light dose and photosensitizer concentration level compared to previous reports.