Healing Effect and Underlying Mechanism of Silver Nanoparticles Prepared Using Carboxymethyl Chitosan under Solar Irradiation

In our previous study,silver nanoparticles were prepared using AgNO_(3) and carboxymethyl chitosan(CMCS)which is commercially available with solar irradiation.In this study,the efficacy and safety of silver nanoparticles prepared by this method were evaluated for healing wounds in rats with diabetes.We also attempted to determine the underlying mechanism and influencing factors of the silver nanomaterial preparation method.Compared with growth factors,silver nanoparticles exhibit better healing effects for rats with diabetes.No remnant silver ions were detected in the major organs of these rats after the application of silver nanoparticles.Silver nanoparticles prepared using CMCS are less toxic than those prepared from the conventional method,promote the proliferation of skin fibroblasts,and are promising as a topical medication for infected wounds.An obvious breakage process of the particles is observed during the growth of nanocrystalline silver in CMCS.In this study,we also attempted to determine whether this method is suitable for synthesizing silver nanoparticles using N-trimethyl chitosan chloride and sodium alginate were used in this particular experiment.The characteristic UV-vis absorbance peak of silver nanoparticles was found only in the reaction mixture containing N-trimethyl chitosan chloride.Our study demonstrates that free radicals are the key factor in this silver nanoparticle preparation method.

Low toxic nitromethane based monopropellant for gas generator cycle air turbo ramjet engine

The present study proposes ethanol-nitromethane mixture as a safe, storable, andlow toxic monopropellant for a gas generator cycle air turbo ramjet engine and evaluates itspropulsion performance. The present study proposes that nitromethane is mixed with ethanolto adjust gas generator combustion temperature. The author developed the computational codefor the present analysis and verified its accuracy. The specific thrust of ethanol-nitromethane isnearly identical to that of ethanol-liquified oxygen and is higher than methanol-hydroxylammonium nitrate aqueous solution and hydrazine. Hydrazine has the highest Ispamong the propellants in the present analysis. However, Isp of ethanol-nitromethane is nearlyequal to that of ethanol-liquified oxygen and higher than those of methanol-hydroxylammonium nitrate aqueous solution, and hydroxyl terminated polybutadiene-ammonium perchlorate. With the propellant-to-air ratio range in the present study, ethanol-nitromethane has the stoichiometric condition at the ram combustor around the propellant-to-air ratio range from 0.2 to 0.25 and can obtain high ram combustion temperature. This resultis favorable for ethanol-nitromethane because it improves the specific thrust and the specificimpulse. Therefore, ethanol-nitromethane can be a promising low-toxic liquid monopropellantfor the air turbo ramjet engine.

Spherical lanthanide nanoclusters toward white-light emission and cell membrane imaging

Lanthanide doping is an effective strategy for modulating the emission of emitters.Herein,by changing the cluster composition to control the energy transfer pathway,the application potential of high-nuclearity lanthanide cluster(HLC)as white-light emitter has been confirmed for the first time.Specifically,by precisely controlling the proportion of GdIII,TbIII,and EuIII ions in reactants,we obtained a spherical heterotrimetallic nanocluster Gd_(10)Tb_(12)Eu_(10),a white-light emitter with quantum yield(QY)of 12.58%and lifetime of 327.14μs.High-resolution electrospray ionization mass spectrometry(HRESI-MS)demonstrates that homometallic nanoclusters Ln_(32)(Ln=Gd,Tb,and Eu)are tetracationic clusters and are highly stable in solution.The peripheral dense organic ligands provide a protective layer for the cluster core,which improves the stability of Ln_(32) in aqueous solution,avoids the contact between metal centers and bioactive molecules,and greatly reduces the biological toxicity.In cell imaging experiments,cationic clusters Ln_(32) are mainly localized on the cell membrane with negative charge distribution.As far as we know,this is the first time that spherical lanthanide nanoclusters have been used for membrane imaging of living cell,opening the door for the application of HLCs in biological imaging.

Photodynamic inheritance from methylene blue to carbon dots against reduction,aggregation,and DNA interference

Photodynamic therapy(PDT)is a treatment that uses light-sensitive drugs and a light source to destroy cancer cells.Methylene blue(MB)is an efficient photosensitizing agent that has been widely used in PDT.However,MB suffers from the hypochromic effect that is caused by self-aggregation and DNA binding in vivo.It is also easily reduced to ineffective leucomethylene blue in the hypoxic environments surrounding solid tumors.In this work,we prepared MB carbon dots(MB-CDs)using MB as the carbon source.The MB-CDs not only inherit the PDT capabilities of MB,but also demonstrate good biocompatibility and low toxicity.Importantly,MB-CDs demonstrate excellent resistance to interference from reduction,aggregation,and DNA interactions.The MB-CDs exhibited satisfactory PDT activities both in vitro and in vivo.The tumor sizes were reduced to below 20%of their original volumes when irradiated by a 590-nm lightemitting diode source.