Polymers
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2015
·Vol. 7
·期 9
·1850-1870
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IF 3.681
Jiaojiao Xu,Beihua Xu,Dan Shou,Xiaojing Xia,Ying Hu
Chronic intracellular infections caused by drug-resistant pathogens pose a challenge to the treatment of chronic osteomyelitis. Such treatment requires an intracellular delivery system for the sustained release of antibiotics such as vancomycin (VCM), which is an antibiotic of last resort used against many clinically resistant bacteria. In this work, we report VCM-loadedN-trimethyl chitosan (TMC) nanoparticles and their potential application for drug delivery. The results showed that the prepared nanoparticles were predominantly spherical in shape with an average particle diameter of 220 nm, a positive zeta potential, and a loading efficiency of 73.65% ± 1.83%. Furthermore, their drug release profile followed the Higuchi model for sustained release, with non-Fickian diffusion. Over a 24-h period, 6.51% ± 0.58% of the drug within the optimized nanoparticles was released.In vitrocytology showed that osteoblasts (OBs) exhibited higher alkaline phosphatase activity (ALP) after exposure to TMC nanoparticle material. Furthermore, TMC nanoparticles increased the uptake of water-soluble quantum dots (QDs) by OBs, and both nanoparticles and VCM/TMC mixtures improved OB proliferative activity. We also investigated the minimum inhibitory concentration (MIC, 60 μg/mL), half maximal inhibitory concentration (IC50, 48.47 μg/mL), diameter of inhibition zone (DIZ, 1.050 cm), and turbidimetric (TB) assay of nanoparticles. All data demonstrated that VCM/TMC nanoparticles had excellent antibacterial activity against the Gram-positive bacteriumStaphylococcus aureus. These findings suggest that VCM-loaded TMC nanoparticles have good potential for the sustained delivery of antibiotics to bone infections.Keywords:vancomycin (VCM);N-trimethyl chitosan (TMC);intracellular infections;nanoparticles
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GLYCOBIOLOGY
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2014
·Vol. 24
·期 12
·1334-1342
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IF 3.747
Zhang Wuxia,Mu Haibo,Dong Dongqi,Wang Dongdong,Zhang Amin,Duan Jinyou
Hyaluronic acid (HA) is an ubiquitous nonsulfated glycosaminoglycan of the extracellular matrix in all mammalian connective tissues. Along with the age growth, HA will lose its N-acetyl groups in vivo; however, the significance of this physiological process remains largely unknown. Herein, three highly N-deacetylated HAs (dHAs), dHA-5 kDa (Mw: 5 kDa, DD: 100%), dHA-16 kDa (Mw: 16 kDa, DD: 94%) and dHA-110 kDa (Mw: 110 kDa, DD: 72%), were generated after hydrazinolysis. Their capability in the activation of antigen-presenting cells (APCs) was compared with that of their respective HAs. Our results demonstrated that both HAs and dHAs could activate the nuclear factor-kappa B (NF-κB) transcription factor in APCs and induced cytokine production through the Toll-like receptor (TLR)/MyD88 pathway. Notably, the capacity of dHAs in cytokine induction was much lower than that of HAs. In addition, the TLR-2 pathway was much involved following the appearance of zwitterionic motifs in dHAs. Thus, our findings highlight that N-deacetylation renders HA divergences in immune response, which might be implicated in age-induced functional change in endogenous glycosaminoglycans due to the structural modification in vivo.
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THERMOCHIMICA ACTA
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2015
·
IF 2.184
Sanguo Peng,Shi Zhang,Ying Zhang,Xiangyang Liu,Maogang He
Mutual diffusion coefficients of several short chain alcohols (ethanol, n -propanol and n -butanol) + n -octane mixtures in the temperature range from 283.2 K to 313.2 K at different concentrations were measured using holographic interferometry. The relation between the mutual diffusion coefficient with temperature, viscosity, concentration and molecular weight is investigated, respectively. The Onsager–Fuoss model is applied to analyse the various influence factors. A new correlation taking into account the effect of the temperature and concentration on the mutual diffusion coefficient is proposed to fit well the experimental data.
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NEW JOURNAL OF CHEMISTRY
·
2013
·Vol. 37
·期 8
·2537-2540
·
IF 2.966
Songbai Liu,Jiahui Zhou
Surfactants have long been underestimated in synthetic organic chemistry despite their great potential in promoting solubility, reactivity and selectivity in metal-mediated cross-couplings. In this study the strategy of surfactant promotion was exemplified in copper-catalyzed N-arylation of indoles in water. The different effects of surfactants during the coupling reaction were first explored. The superior promoting effect of the natural zwitterionic surfactant, betaine, was found and attributed to the capability of the formed complex to stabilize the copper intermediate in the catalytic transformation and facilitate transportation of the reactants. The concept of surfactant promotion through complexation is valuable in metal-mediated cross-couplings. This method also exhibited good recycling ability. This study will greatly facilitate exploration of surfactant promotion in metal-mediated cross-couplings.
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JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES
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2015
·
IF 1.406
L. Zhang,W.D. Yu,X.H. Pan,J.J. Fang,M. Hua,F.M. Chen,J.C. Jiang
The exothermic oxidation of 3-methylpyridine with hydrogen peroxide was analyzed by Reaction Calorimeter (RC1e) in semi-batch operation. Heat releasing rate and heat conversion were studied at different operating conditions, such as reaction temperature, feeding rate, the amount of catalyst and so on. The thermal hazard assessment of the oxidation was derived from the calorimetric data, such as adiabatic temperature rise (ΔT ad ) and the maximum temperature of synthesis reaction (MTSR) in out of control conditions. Along with thermal decomposition of the product, the possibility of secondary decomposition under runaway conditions was analyzed by time to maximum rate (TMR ad ). Also, risk matrix was used to assess the risk of the reaction. Results indicated that with the increase of the reaction temperature, the reaction heat release rate increased, while reaction time and exotherm decreased. With the increase of feeding time, heat releasing rate decreased, but reaction time and exotherm increased. With the amount of the catalyst increased, heat releasing rate increased, reaction time decreased and exothermic heat increased. The risk matrix showed that when the reaction temperature was 70 °C, feeding time was 1 h, and the amount of catalyst was 10 g and 15 g, respectively, the reaction risk was high and must be reduced.
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
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2014
·Vol. 18
·期 10
·2693-2699
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IF 2.234
Cui Jingjie,Chen Shaowei,Liu Hong,Huang Zhen
6-Phosphate aminopurine ( 6 PA), a purine analog, is usually used in clinical anticancer treatment and biochemical research. Up to now, to the best of our knowledge, no literature about the electrochemical behaviors of 6 PA has been reported. In this study, nano-p–n junction heterostructures based on TiO 2 nanobelts were produced by the assembly of p-type semiconducting NiO nanoparticles onto the n-type surface-coarsened TiO 2 nanobelts. The electrochemical behaviors of 6 PA were investigated by different voltammetric techniques in a phosphate buffer solution of pH 7.4 using the heterostructures as the sensing electrode. Compared with single-phase TiO 2 nanobelt electrodes, the resulting chemically modified electrodes exhibited higher surface accumulation ability and enhanced electrocatalytic activities in the oxidation for 6 PA, with an irreversible oxidation peak at +0.91 V. It is proposed that the nano-p–n junction heterostructures played an important role in the enhancement of charge transport in the sensing electrodes. The results suggest that the nanoengineered TiO 2 nanobelts might be a promising candidate for biosensing applications of nucleic acid drugs that will be of significance to diagnostic medicine and molecular biology research.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2017
·Vol. 134
·期 14
·
IF 1.86
Hongjiao Wang,Shunli Liu,Aokai Zhang,Kewen Li,Olayinka Oderinde,Fang Yao,Guodong Fu
A series of N-succinyl Chitosan (NSCS) hydrogel derived from different substitution degree of NSCS were fabricated through the zinc ions crosslinking. Subsequently, a light-weight, transparent, and hierarchical NSCS-Zn(II) film was obtained by drying the hydrogel. The hierarchical structure of NSCS-Zn(II) film was confirmed by scanning electron microscopy. The NSCS-Zn(II) film exhibited excellent mechanical strength because of the preferential formation of the alignment structure. The tensile strength and Young's modulus reaches 119.3 MPa and 2.67 GPa when the NSCS substitution degree was 91.95%. Furthermore, a remarkable and enhanced broad-spectrum bactericidal properties of the NSCS-Zn(II) film was revealed through E. coli and S. aureus exposure, respectively. These features indicated that NSCS-Zn(II) film is a promising material that can be used in biomedical engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44664.
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ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Zhenggang Zhang,Yang Jiang,Zhe Peng,Shanshan Yang,Huan Lin,Meng Liu,Deyu Wang
Although nanoengineering provides improved stability of Si-based nanostructures, a facile and efficacious method to directly use raw Si practices is still absent. Herein, we report a pyrolyzed N-doped binder network to improve the cycling stability of raw Si particles. Such an N-doped binder network is formed at a conformal pyrolysis condition of the electrode binder using polyacrylonitrile and provides a tight encapsulation of the Si particles with significantly improved cycling stability. In contrast to the single Si particles that pulverize and lose the total capacity at the 20th cycle, the discharge capacity could be retained ∼1700 mA h g–1 at the 100th cycle for the Si particles imbedded in the pyrolyzed N-doped binder network. Our results demonstrate that such a facile remedy could significantly improve the cycling stability of raw Si particles for high-energy-density lithium-ion batteries.
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Nature Protocols
·
2024
·
IF 13.1
Wu Yueming,Chen Kang,Wang Jiangzhou,Dai Wenhui,Yu Haowen,Xie Xinyi,Chen Minzhang,Liu Runhui
Synthetic polypeptides, also known as poly(α-amino acids), have the same polyamide backbone structures as natural proteins and peptides. As an important class of biomaterials, polypeptides have been widely used because of their biocompatibility, bioactivity and biodegradability. Ring-opening polymerization of N -carboxyanhydride (NCA) is a classical and widely used method for the synthesis of polypeptides. The dominantly used primary amine–initiated NCA polymerization can yield well-defined polymers and complex macromolecular architectures, but the reaction is slow and sensitive to moisture, making it necessary to use anhydrous solvents and a glovebox. One solution is to use lithium hexamethyldisilazide (LiHMDS) as the initiator, as described in this protocol. LiHMDS-initiated NCA polymerization is less sensitive to moisture and can be carried out in an open vessel outside the glovebox. It is also very fast; the reaction can be complete within 5 min to produce 30-mer polypeptides. In this protocol, poly(γ-benzyl- l -glutamate) is prepared as an example, but the protocol can easily be adapted to the synthesis of other polypeptides by generating NCAs from different amino acids, making it particularly suitable for the efficient parallel synthesis of polypeptide libraries. We provide detailed procedures for NCA synthesis and purification, the method of polymer end-group modification and measurement of polymerization kinetics and reactivity ratio. The procedure for synthesis of monomers and polymerization to form polypeptides requires <1 d. The superfast and open-vessel NCA polymerization method described here will probably enable a wide range of applications in the synthesis and functional study of polypeptide biomaterials.
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MATERIALS CHEMISTRY AND PHYSICS
·
2025
·
IF 4.7
Xu Wang,Quan Gao,Yongfa Zhou,Zhihan Wang
Sustainable cellulose has attracted considerable attention in the field of renewable supercapacitor owing to its low-cost and lightweight properties. However, it is still a challenge to enhance their electrochemical performance. Here, nitrogen (N) and phosphorous (P) co-doped carbon aerogels derived from cellulose were synthesized via the sol-gel-lyophilization-carbonization method. Their structures were determined by scanning electron microscopy (SEM), nitrogen sorption isotherm, and X-ray photoelectron spectroscopy (XPS). The N/P co-doped carbon aerogel exhibited significantly enhanced porous surface properties, and the increasing contents of the N and P could provide more defects and active sites. Therefore, the sample achieved a high specific capacitance of 235.5 F g −1 at 0.5 A g −1 , while also demonstrating good retention of specific capacitance with 62.6 % of initial capacitance at 20 A g −1 . The electrode exhibited 87 % capacitance retention and an excellent coulombic efficiency of close to 100 % after undergoing 10,000 cycles at a current density of 6 A g −1 . Overall, the synthesized cellulose carbon aerogels, modified through doping engineering, have been identified as a promising candidate for supercapacitor electrodes.
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PROCESS SAFETY PROGRESS
·
2017
·Vol. 37
·期 3
·355-361
·
IF 0.812
Min Hua,Min Qi,Xuhai Pan,Wendi Yu,Lu Zhang,Juncheng Jiang
Alkyl pyridine-N-oxide can decompose to pyridine which readily leads to explosion accident in air. Therefore, risk analysis and inherently safer design are necessary for this process. This article aims to study the thermal hazards of the process of 3-methylpyridine oxidized by hydrogen peroxide, and then the corresponding Inherently Safer Designs (ISDs) were proposed. The inherent hazards during the process were first qualitatively evaluated by Qualitative Assessment for Inherently Safer Design. Then, the reaction calorimeter was employed to analyze the thermal hazards of the target reaction. Meanwhile, the Integrated Inherent Safety Index methods were simplified to quantitatively estimate the level of inherent safety of the process. The results show that the potential risk of the process is 87.2% which is at the high risk level. Based on the hazard identification and assessment results, three ISDs, namely adding catalyst (ISD I), improving reaction condition (ISD II), and using a tubular (ISD III), were proposed to enhance the safety. Finally, combining comparative experiments with ISI methods, an effect evaluation model for ISD was established to verify the rationality of the ISDs. The results indicate that the reaction hazards are diminished when three ISDs are utilized in production process. The inherent safety level of the reaction is increased by 22.2%, 50.7%, and 31.8%, respectively. © 2017 American Institute of Chemical Engineers Process Process Saf Prog 37:355–361, 2018
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ANALYTICA CHIMICA ACTA
·
2011
·
IF 4.311
Haixia Fan,Yan Li,Dan Wu,Hongmin Ma,Kexia Mao,Dawei Fan,Bin Du,He Li,Qin Wei
Bisphenol A (BPA), which could disrupt endocrine system and cause cancer, has been considered as an endocrine disruptor. Therefore, it is very important and necessary to develop a sensitive and selective method for detection of BPA. Herein, nitrogen-doped graphene sheets (N-GS) and chitosan (CS) were used to prepare electrochemical BPA sensor. Compared with graphene, N-GS has favorable electron transfer ability and electrocatalytic property, which could enhance the response signal towards BPA. CS also exhibits excellent film forming ability and improves the electrochemical behavior of N-GS modified electrode. The sensor exhibits a sensitive response to BPA in the range of 1.0 × 10 −8 –1.3 × 10 −6 mol L −1 with a low detection limit of 5.0 × 10 −9 mol L −1 under the optimal conditions. Finally, this proposed sensor was successfully employed to determine BPA in water samples with satisfactory results.
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