Preparation, Characterization and in vitro Release of Chitosan-stavudine Conjugate Nano-prodrug

Chitosan-stavudine （d4T） conjugate with a succinic spacer was synthesized via carbodiimide coupling reaction and structurally characterized. In order to nanosize it for improving its therapeutic properties, the chitosan-5＇-O-succinyl-d4T conjugate was crosslinked with sodium tripolyphosphate （TPP） to obtain the chitosan-d4T conjugate nano-prodrug. The morphologies of chitosan-d4T conjugate nanoparticles were observed by transmission electron microscopy （TEM）, and their zeta potential, particle size, and polydispersity （size distribution） were measured by the dynamic light scattering （DLS） techniques. In vitro drug release studies at pH 1.1 and pH 7.4 indicate that the crosslinked chitosan-d4T conjugate nano-prodrug can prevent the coupled d4T from leaking out before entering the target viral reservoirs and provide a mild sustained release without the burst release. The results reveal that constructing conjugated chitosan nano-prodrugs may be a promising approach for improving the therapy efficacy of drugs in antiviral treatment.

Investigates of substrate mingling ratio and organic loading rate of KOH pretreated corn stover and pig manure in batch and semi-continuous system:Anaerobic digestion performance and microbial characteristics

The effects of substrate mingling ratio(SMR)(1:1,1:2,1:3,3:1,and 2:1)and organic loading rate(OLR)(50-90 g total solids per liter per day)on anaerobic co-digestion performance and microbial characteristics were investigated for pig manure(PM)and pretreated/untreated corn stover in batch and semicontinuous anaerobic digestion(AD)system.The results showed that SMR and pretreatment affected co-digestion performance.The maximum cumulative methane yield of 428.5 ml·g^(-1)(based on volatile solids(VS))was obtained for PCP13,which was 35.7%and 40.0%higher than that of CSU and PM.In the first 5 days,the maximum methane yield improvement rate was 378.1%for PCP13.The daily methane yield per gram VS of PCP13 was 11.4%-18.5%higher than that of PC_(U)13.Clostridium_sensu_stricto_1,DMER64,and Bacteroides and Methanosaeta,Methanobacterium,and Methanospirillum had higher relative abundance at the genus level.Therefore,SMR and OLR are important factor affecting the AD process,and OLR can affect methane production through volatile fatty acids.

Highly Stereoselective Synthesis of trans-3-Chloro-β-lactams from Imines and Mixed Chloroacetyl and Nitroacetyl Chlorides

A series of trans-3-chloro-β-lactams was synthesized stereospecifically from imines and chloroacetyl chloride or a mixture of chloroacetyl chloride and nitroacetyl chloride, prepared from vinylidene chloride and a mixture of concentrated nitric acid and sulfuric acid, in the presence of triethylamine. The reaction of vinylidene chloride and the mixed acid was investigated. The formation mechanism of chloroacetyl chloride and nitroacetyl chloride and their reaction process with imines were proposed.

Classification of blocker and non-blocker of hERG potassium ion channel using a support vector machine

The human ether-a-go-go related gene （hERG） channel is responsible for the repolarization during the action potential, and blockage of that may result in severe cardiotoxicity and sudden death. In this study, a dataset containing 1969 compounds was compiled from literature and FDA-approved drugs. Using a support vector machine （SVM）, two groups of computational models were built to distinguish whether a compound is a blocker or non-blocker of hERG potassium ion channel. These mod- els fit generally satisfactory. The 100 models built with MACCS fingerprints （Model Group A） showed an average accuracy of 90% and an average matthews correlation coefficient （MCC） value of 0.77 on the test sets. The 100 models built with selected MOE descriptors （Model Group B） showed an average accuracy of 89% and an average MCC value of 0.74 on the test sets. Molecular hydrophobicity and lipophilicity were found to be very important factors which lead to block the hERG potassium ion channel. Some other molecular properties such as electrostatic properties, features based on van der Waals surface area, the number of rigid bonds and molecular surface rugosity also played important roles in blocking bERG potassium ion channel.

An efficient and facile synthesis of N-Cbz-β-aminoalkanesulfonamides

An efficient method for the synthesis of N-Cbz-β-aminoalkanesulfonamides was described.N-Cbz-β-aminoalkanesulfonamides were readily prepared in good yields from a variety of amino alcohols,including optically active ones,via N-Cbz protection with benzyl chloroformate,Mitsunobu esterification reaction with thiolacetic acid,N-chlorosuccinimide oxidation,and ammonolysis process.

Enhancing water repellence and mechanical properties of antibacterial gelatin/Ce(Ⅲ) fiber by heat treatment

The water repellence and mechanical properties of the gelatin/Ce（Ⅲ） fiber（GCe fiber） were improved by heat treatment,which was an easy and non-toxic method.The microscopic morphology,mechanical properties,antibacterial activity,and cell culture of the GCe fibers by heat treatment（HGCe fiber） were investigated.It was found that the water repellence and mechanical properties of the HGCe fibers increased significantly along with temperature increase.SEM observation showed that HGCe fibers had a fairly smooth surface and a compact structure.Detailed characterization revealed that the HGCe fibers exhibited similar antibacterial activity with the GCe fibers against Staphylococcus aureus.In addition,the results of cell culture by morphological assessment and methylthiazolyl tetrazolium assay（MTT assay） indicated the good biocompatibility of GCe fibers.Therefore,the HGCe fibers could be a promising candidate biomaterial for biomedicine applications.

Stereoselective synthesis of cis- and trans-4-acyl-β-lactams from vicinal diketones and ketoaldehydes

4-Acyl-β-lactams are important synthetic intermediates in both pharmaceutical and organic chemistry. Cis- and trans-4-acyl-β- lactams were synthesized stereoselectively from vicinal diketones via the formation of bulky and less bulky diimines as key intermediates, respectively. The diimines reacted with acyl chloride in the presence of triethylamine to give rise to the corre- sponding 4-imino-β-lactams, which were further hydrolyzed to afford 4-acyl-β-lactams. The cis- and trans selectivity is de- pended on the steric hindrance of the imine N-substituents. A series of cis-4-acyl-β-lactams were synthesized from vicinal ketoaldehydes via the formation of their monoimines and diimines as intermediates. Pyruvic aldehyde produced cis-4-acetyl-β- lactams and cis-4-formyl-β-lactams, respectively, through the reactions of its monoimine and diimine with acyl chlorides. Phenylglyoxal generated cis-4-benzoyl-β-lactams via its monoaldimine.