具有抗菌性能的新型载银细菌纤维素纳米纤维(英文)

In this work, we describe a novel facile method to prepare long one-dimensional hybrid nanofibers by using hydrated bacterial cellulose nanofibers（BCF） as a template. Silver（Ag） nanoparticles with an average diameter of 1.5 nm were well dispersed on BCF via a simple in situ chemical-reduction between AgNO3 and NaBH4 at a relatively low temperature. A growth mechanism is proposed that Ag nanoparticles are uniformly anchored onto BCF by coordination with BC-containing hydroxyl groups. The bare BCF and as-prepared Ag/BCF hybrid nanofibers were characterized by several techniques including transmission electron microscopy, X-ray diffraction, thermogravimetric analyses, and ultraviolet-visible（UV-Vis） absorption spectra. The antibacterial properties of Ag/BCF hybrid nanofibers against Escherichia coli（E. coli, Gram-negative） and Staphylococcu saureus（S. saureus, Gram-positive） bacteria were evaluated by using modified Kirby Bauer method and colony forming count method. The results show that Ag nanoparticles are well dispersed on BCF surface via in situ chemical-reduction. The Ag/BCF hybrid nanofiber presents strong antibacterial property and thus offers its candidature for use as functional antimicrobial agents.     

Enhanced Antimicrobial Activity of Biocompatible Bacterial Cellulose Films via Dual Synergistic Action of Curcumin and Triangular Silver Nanoplates

Curcumin and triangular silver nanoplates (TSNP)-incorporated bacterial cellulose (BC) films present an ideal antimicrobial material for biomedical applications as they afford a complete set of requirements, including a broad range of long-lasting potency and superior efficacy antimicrobial activity, combined with low toxicity. Here, BC was produced by Komagataeibacter medellinensis ID13488 strain in the presence of curcumin in the production medium (2 and 10%). TSNP were incorporated in the produced BC/curcumin films using ex situ method (21.34 ppm) and the antimicrobial activity was evaluated against Escherichia coli ATCC95922 and Staphylococcus aureus ATCC25923 bacterial strains. Biological activity of these natural products was assessed in cytotoxicity assay against lung fibroblasts and in vivo using Caenorhabditis elegans and Danio rerio as model organisms. Derived films have shown excellent antimicrobial performance with growth inhibition up to 67% for E. coli and 95% for S. aureus. In a highly positive synergistic interaction, BC films with 10% curcumin and incorporated TSNP have shown reduced toxicity with 80% MRC5 cells survival rate. It was shown that only 100% concentrations of film extracts induce low toxicity effect on model organisms’ development. The combined and synergistic advanced anti-infective functionalities of the curcumin and TSNP incorporated in BC have a high potential for development for application within the clinical setting.     

载银介孔氧化硅防污剂的制备及其防污机理研究

采用化学法制备出载银介孔氧化硅(Ag-MSN)粉体,通过扫描电镜(SEM)和透射电镜(TEM)表征纳米材料的微观形貌和尺寸,利用X射线衍射(XRD)确定纳米材料的成分并结合公式确定纳米银的粒径;通过平板培养法和分光光度计法揭示载银介孔氧化硅对于海洋微生物(需钠弧菌)的抗菌效果和机理。将载银介孔氧化硅粉体作为主要颜料与有机硅树脂复合,得到具有一定抑菌性能的涂层。该研究成果将有助于揭示纳米银防污机理,并对绿色海洋防污剂的制备与应用起到重要的促进作用。     

Synthesis of Silver Nanoparticles and Detection of Glucose via Chemical Reduction with Nanocellulose as Carrier and Stabilizer

The application of silver nanoparticles (AgNPs) in antibacterial materials, glucose detection, etc., is of broad interest for researchers around the world. Nanocellulose with many excellent properties can be used as a carrier and stabilizer to assist in the synthesis of AgNPs. In this study, cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were used to assist in the synthesis of AgNPs under the reduction of glucose and detection of glucose concentration under different conditions. Transmission electron microscopy (TEM) analysis showed that the AgNPs in the nanocellulose-AgNPs (NC-AgNPs) system were roughly spherical and randomly distributed on the nanocellulose. In the whole reaction system, when the concentration of nanocellulose is 0.11 mg/mL, the concentration of silver ammonia solution is 0.6 mM, and the mixing time is 2.5 h, according to the UV-Vis analysis, the absorbance of CNF-AgNPs at 425 nm exhibited a good linear relationship (R² = 0.9945) with the glucose concentration range (5–50 μM), while the absorbance of CNC-AgNPs at 420 nm showed a good linear relationship (R² = 0.9956) with the glucose concentration range (5–35 μM). The synthesis of NC-AgNPs can be further developed into a sensor with higher sensitivity and higher stability for detecting glucose concentration and a material with antibacterial effects.     

Silver Nanoparticles Biocomposite Films with Antimicrobial Activity: In Vitro and In Vivo Tests

Overuse of antimicrobials by the population has contributed to genetic modifications in bacteria and development of antimicrobial resistance, which is very difficult to combat nowadays. To solve this problem, it is necessary to develop new systems for the administration of antimicrobial active principles. Biocomposite systems containing silver nanoparticles can be a good medical alternative. In this context, the main objective of this study was to obtain a complex system in the form of a biocomposite film with antimicrobial properties based on chitosan, poly (vinyl alcohol) and silver nanoparticles. This new system was characterized from a structural and morphological point of view. The swelling degree, the mechanical properties and the efficiency of loading and release of an anti-inflammatory drug were also evaluated. The obtained biocomposite films are biocompatibles, this having been demonstrated by in vitro tests on HDFa cell lines, and have antimicrobial activity against S. aureus. The in vivo tests, carried out on rabbit subjects, highlighted the fact that signs of reduced fibrosis were specific to the C2P4.10.Ag1-IBF film sample, demonstrated by: intense expression of TNFAIP8 factors; as an anti-apoptotic marker, MHCII that favors immune cooperation among local cells; αSMA, which marks the presence of myofibroblasts involved in approaching the interepithelial spaces for epithelialization; and reduced expression of the Cox2 indicator of inflammation, Col I.     

纤维素纳米晶改性光固化水性聚氨酯丙烯酸酯及其性能研究

以纤维素纳米晶（ CNC）作为添加物,对紫外光固化水性聚氨酯丙烯酸酯（ UV-WPUA）进行共混改性。通过实时红外、转矩流变仪、紫外 -可见光分光光度计、扫描电子显微镜（ SEM）、电子万能试验机等表征手段探究了 CNC的添加量对复合树脂及其光固化涂层的性能影响。结果表明：当 CNC的添加量为 2%时, CNC颗粒在复合树脂中分散性良好,复合涂层的可见光透过率大于 85%,铅笔硬度 3H,附着力 0级,拉伸强度 9. 8 MPa,复合涂层的综合性能最好。     

New Antivirals and Antibacterials Based on Silver Nanoparticles

The rediscovery of the medical uses of silver provides another noticeable example, this time at the interface of chemistry and medicine, of the real (and nonlinear) progress of scientific research. Several new silver-based antimicrobial products have thus been commercialized in the last two decades. Next-generation antibacterials and antivirals of broad scope, low toxicity and affordable cost, we argue in this study, will be based on microencapsulated Ag nanoparticles.     

Lignocellulosic Biomass Waste-Derived Cellulose Nanocrystals and Carbon Nanomaterials: A Review

Rapid population and economic growth, excessive use of fossil fuels, and climate change have contributed to a serious turn towards environmental management and sustainability. The agricultural sector is a big contributor to (lignocellulosic) waste, which accumulates in landfills and ultimately gets burned, polluting the environment. In response to the current climate-change crisis, policymakers and researchers are, respectively, encouraging and seeking ways of creating value-added products from generated waste. Recently, agricultural waste has been regularly appearing in articles communicating the production of a range of carbon and polymeric materials worldwide. The extraction of cellulose nanocrystals (CNCs) and carbon quantum dots (CQDs) from biomass waste partially occupies some of the waste-recycling and management space. Further, the new materials generated from this waste promise to be effective and competitive in emerging markets. This short review summarizes recent work in the area of CNCs and CQDs synthesised from biomass waste. Synthesis methods, properties, and prospective application of these materials are summarized. Current challenges and the benefits of using biomass waste are also discussed.     

聚乳酸基纤维素纳米晶体抗菌包装材料的制备及其性能研究

为改善聚乳酸(PLA)膜的力学性能、阻隔性能和抑菌性能,通过溶液浇铸法制备纤维素纳米晶体(CNC)和槐糖脂(SL)掺杂的PLA复合抗菌膜,探究SL含量(10%)不变时,CNC的含量对PLA/SL/CNC的力学性能、亲疏水性、水蒸气阻隔性和抑菌性能的影响。结果表明:PLA复合膜具有较好的透光性。CNC含量为8%时,CNC与PLA相容性较差。相比纯PLA,PLA/SL/CNC(6%)的拉伸强度高达68.6 MPa,提高93.8%;PLA/SL/CNC(6%)的韧性为36.5×10⁸J/m³,增加46%。PLA/SL/CNC(6%)水接触角为86°,具有疏水性。PLA/SL/CNC(6%)的水蒸气透过系数为2.4(g·cm)/(Pa·s·cm²),与纯PLA相比降低36.8%。PLA/SL/CNC(6%)与利斯特氏菌和金黄色葡萄球菌共培养24h,菌落数分别为0.8 lgCFU/mL和0.4 lgCFU/mL,具有较好的抑菌效果。     

银粒子抗菌材料在涂料中的应用研究

以银粒子为抗菌剂制备聚氨酯抗菌涂料。讨论了银粒子的制备条件,及其加入聚氨酯涂料中的比例对涂料抗菌性能的影响。     

Facile Incorporation of Silver Nanoparticles into Quaternized Poly(2‐(Dimethylamino)Ethyl Methacrylate) Brushes as Bifunctional Antibacterial Coatings

A simple strategy to fabricate bifunctional antibacterial coatings via in situ synthesis and incorporation of silver nanoparticles (AgNPs) into quaternized poly(2‐(dimethylamino)ethyl methacrylate) (qPDMAEMA) brushes without using any reducing agents is reported. PDMAEMA brushes are prepared on Si wafer substrates via surface‐initiated reverse atom transfer radical polymerization, which then are quaternized with ethyl bromide and hexyl bromide, respectively. The resulting qPDMAEMA‐AgNP nanocomposite coatings are characterized by using Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE‐SEM), and Raman spectroscopy. FE‐SEM and Raman results indicate that the AgNPs with an average diameter of 35 nm are successfully loaded into the qPDMAEMA brushes. Furthermore, the antibacterial activities of the qPDMAEMA‐AgNP nanocomposite coatings against Gram‐positive Staphylococcus aureus and Gram‐negative Escherichia coli are investigated by both disc diffusion and colony‐forming unit methods. The results show excellent antibacterial properties of the nanocomposite coatings. The influence of the length of the quaternization agents on their antibacterial properties is also investigated.

     

银纳米微粒接枝木纤维的制备及抗菌性能研究

以聚乙烯吡咯烷酮(PVP)为稳定剂和分散剂,硼氢化钠为还原剂制备了聚乙烯吡咯烷酮-银纳米微粒(PVP-Ag NPs),并将其通过硅烷偶联剂接枝到木纤维上,得到了具有抗菌活性的木纤维。利用扫描电子显微镜(SEM)和傅里叶-红外光谱(FT-IR)对PVP-Ag NPs接枝的木纤维进行了结构形貌的表征,并且通过热重分析仪(TG)分析其热稳定性能。结果表明,PVP-Ag NPs接枝木纤维的最佳反应条件是硅烷偶联剂用量4%、偶合时间5 h及接枝时间10 h,此条件下得到PVP-Ag NPs接枝木纤维的接枝率为5.8%;PVP-Ag NPs接枝的木纤维对革兰氏阳性菌金黄色葡萄球菌、蜡状芽疱杆菌、革兰氏阴性菌大肠埃希氏菌以及耐药性细菌耐甲氧西林金黄色葡萄球菌这4种菌种的抑菌率均大于95%,此外,PVP-Ag NPs接枝到木纤维板上的抗菌效果也较好。     

壳聚糖/烟用二乙酸纤维的抗菌性能研究

以白葡萄球菌、大肠杆菌和枯草芽孢杆菌为试验菌种,研究了壳聚糖改性后烟用二乙酸纤维丝束纤维的抗菌效果。发现改性纤维抗菌活性随着壳聚糖浓度和脱乙酰度增加而提高;通过扫描电镜观察,发现改性纤维表面菌体被抑制;通过电镜照片分析和红外光谱分析表明壳聚糖和二乙酸纤维表面发生了物理吸附并可能伴有化学交联作用。     

纳米SiO2载银抗菌剂的研究

以化学沉淀法制备得到多孔纳米SiO2,采用吸附法在其表面负载银,用载银粉体的抑菌圈直径表征抗茵性能,研究了吸附时间、硝酸银浓度及吸附温度与负载量的关系,并考察了焙烧温度与抗菌性能的关系。     

Microstructural,Thermal, Crystallization,and Water Absorption Properties of Films Prepared from Never-Dried and Freeze-Dried Cellulose Nanocrystals

In this paper, the microstructural, optical, thermal, crystallization, and water absorption properties of films prepared from never-dried (ND) and freeze-dried (FD) cellulose nanocrystals (CNCs) are reported. Morphology of the ND CNCs reveals a needle-like structure, while after freeze-drying, they show a flake-like morphology. Microstructural analysis of ND and FD CNCs are further studied via small angle X-ray scattering to probe interactions. ND CNCs yield a transparent film with a low surface roughness (14 ± 4 nm), while the FD CNC film evidence a significant reduction of their transparency due to their higher surface roughness (134 ± 20 nm). Although Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy analyses reveal no chemical change occurs during the freeze-drying process, yet a more intense thermal degradation profile is observed for FD CNC film, probably due to the higher oxygen ingress within the gaps created between the stacked flakes. This, in turn, results in a greater loss of crystallinity at a higher temperature (300 °C) compared to the ND CNC film. A rapid decrease in water contact angle of the FD CNC film proves that the morphology of flakes and their orientation within the film has a strong influence in increasing water absorption capacity.     

细菌纤维素/氧化亚铜膜的抗菌性能及机制研究

采用抗菌试验来表征不同配方的细菌纤维素/氧化亚铜膜的特性,用大肠埃希菌和黑根霉对细菌纤维素/氧化亚铜膜进行定性分析;用大肠埃希菌和金黄色葡萄球菌对细菌纤维素/氧化亚铜膜进行定量分析,得出抑菌率。通过电镜试验,初步观察样品对细菌细胞的破坏机制,试验结果表明:不同配方的细菌纤维素/氧化亚铜膜的抗菌能力不同,抗菌机制主要是改变细胞膜通透性和抑制细胞复制,最终导致细胞死亡。     

聚多巴胺功能化纳米银粒子制备及抗菌性能研究

采用一步法,以聚多巴胺(PDA)为还原剂和保护剂,制备PDA功能化的纳米银粒子(PDA-nanoAg)。提出PDA-nanoAg合成机理,并考察其在水相中的分散稳定性。通过紫外-可见吸收分光光度计(UV-Vis)、透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FTIR)对产物形貌和结构进行表征。采用肉汤稀释法测试PDAnanoAg的抗菌性能。结果表明,所制备的PDA-nanoAg平均粒径为50 nm,具有良好的稳定分散性;对埃希氏大肠杆菌(E.coli)、金黄色葡萄球菌(S.aureus)的最小抑菌浓度(MIC)为7.56 mg/L,最小杀菌浓度(MBC)为30.24mg/L。     

壳聚糖/纤维素抗菌纤维的研究与展望

壳聚糖是一种广谱抗菌剂，和纤维素具有相似的分子结构和良好的相容性，可用于改性纤维素纤维研制抗菌纤维。目前，基于纤维素纤维的工业生产方法,这种抗菌纤维的研究开发主要集中在粘胶法上，随着纤维素纤维溶剂法纺丝的出现，抗菌纤维的研究也应该向这种环保，节能，直接的方法转变，本文在对壳聚糖／粘胶纤维的研究工作作了总结之后，对这种抗菌纤维的溶剂法纺丝作了初步探讨和展望。     

Investigation of the Characteristics and Antibacterial Activity of Polymer-Modified Copper Oxide Nanoparticles

The proliferation of drug-resistant pathogens continues to increase, giving rise to serious public health concerns. Many researchers have formulated metal oxide nanoparticles for use as novel antibacterial agents. In the present study, copper oxide (CuO) was synthesized by simple hydrothermal synthesis, and doping was performed to introduce different polymers onto the NP surface for bacteriostasis optimization. The polymer-modified CuO NPs were analyzed further with XRD, FTIR, TEM, DLS and zeta potential to study their morphology, size, and the charge of the substrate. The results indicate that polymer-modified CuO NPs had a significantly higher bacteriostatic rate than unmodified CuO NPs. In particular, polydopamine (PDA)-modified CuO (CuO-PDA) NPs, which carry a weakly negative surface charge, exhibited excellent antibacterial effects, with a bacteriostatic rate of up to 85.8 ± 0.2% within 3 h. When compared to other polymer-modified CuO NPs, CuO-PDA NPs exhibited superior bacteriostatic activity due to their smaller size, surface charge, and favorable van der Waals interactions. This may be attributed to the fact that the CuO-PDA NPs had relatively lipophilic structures at pH 7.4, which increased their affinity for the lipopolysaccharide-containing outer membrane of the Gram-negative bacterium Escherichia coli.     

Cellulose Nanocrystals as a Sustainable Raw Material: Cytotoxicity and Applications on Healthcare Technology

Cellulose nanocrystals (CNCs) are an environmentally friendly natural material, consisting of rod‐like crystalline nanoparticles, called whiskers, or nanocrystalline cellulose. The derivation of different natural sources, aligned to their biocompatibility, biodegradability, and versatility, make them a class of fascinating materials with widespread industrial use. In addition, the cellulose species possess intriguing physicochemical and mechanical properties. This paper provides an overview of recent progress in the area of cellulosic nanocomposites, along with details of their structure and liquid crystalline behavior as nematic and cholesteric lyotropic materials. Guidance is subsequently provided for the physicochemical analysis of these materials, including X‐ray diffraction, transmission electron microscopy, optical evaluation, thermogravimetric analysis, and differential scanning calorimetry. Additionally, the functional chemical and physical properties of CNCs are correlated to the resulting nanotoxicity in in vitro and in vivo assays. This review points to relevant concerns, such as sources for the synthesis of CNCs, the nanomaterial size, and the surface chemistry, that must be overcome in order to attain safe use of CNC‐based nanomaterials. The challenging perspectives on the ongoing research are presented in order to explore the technological and industrial perspectives on the use of CNC for the generation of cost‐effective advanced nanomaterials based on cellulosic fibers.