Water-Insensitive Synthesis of Poly-β-Peptides with Defined Architecture

Biocompatible and proteolysis-resistant poly-β-peptides have broad applications and are dominantly synthesized via the harsh and water-sensitive ring-opening polymerization of β-lactams in a glovebox or using a Schlenk line, catalyzed by the strong base LiN(SiMe₃)₂. We have developed a controllable and water-insensitive ring-opening polymerization of β-amino acid N-thiocarboxyanhydrides (β-NTAs) that can be operated in open vessels to prepare poly-β-peptides in high yields, with diverse functional groups, variable chain length, narrow dispersity and defined architecture. These merits imply wide applications of β-NTA polymerization and resulting poly-β-peptides, which is validated by the finding of a HDP-mimicking poly-β-peptide with potent antimicrobial activities. The living β-NTA polymerization enables the controllable synthesis of random, block copolymers and easy tuning of both terminal groups of polypeptides, which facilitated the unravelling of the antibacterial mechanism using the fluorophore-labelled poly-β-peptide.     

Rapid Capillary-Assisted Solution Printing of Perovskite Nanowire Arrays Enables Scalable Production of Photodetectors

Despite recent progress in producing perovskite nanowires (NWs) for optoelectronics, it remains challenging to solution-print an array of NWs with precisely controlled position and orientation. Herein, we report a robust capillary-assisted solution printing (CASP) strategy to rapidly access aligned and highly crystalline perovskite NW arrays. The key to the CASP approach lies in the integration of capillary-directed assembly through periodic nanochannels and solution printing through the programmably moving substrate to rapidly guide the deposition of perovskite NWs. The growth kinetics of perovskite NWs was closely examined by in situ optical microscopy. Intriguingly, the as-printed perovskite NWs array exhibit excellent optical and optoelectronic properties and can be conveniently implemented for the scalable fabrication of photodetectors.     

Unpaired 3d Electrons on Atomically Dispersed Cobalt Centres in Coordination Polymers Regulate both Oxygen Reduction Reaction (ORR) Activity and Selectivity for Use in Zinc–Air Batteries

Reversible oxygen conversion is important for various green energy technologies. Herein we synthesize a series of bimetallic coordination polymers by varying the Ni/Co ratio and using HITP (HITP=2,3,6,7,10,11‐hexaiminotriphenylene) as the ligand, to interrogate the role of metal centres in modulating the activity of the oxygen reduction reaction (ORR). Co₃HITP₂ and Ni₃HITP₂ are compared. Unpaired 3d electrons in Co₃HITP₂ result in less coplanarity but more radical character. Thus, despite of a reduced crystallinity and conductivity, the best ORR activity, comparable to 20 % Pt/C, is obtained for Co₃HITP₂, showing the 3d orbital configuration of the metal centre promotes ORR. Experimental and DFT studies show a transition of ORR pathway from four‐electron for Co₃HITP₂ to two‐electron for Ni₃HITP₂. Rechargeable zinc–air batteries using Co₃HITP₂ as the air cathode catalyst demonstrate excellent energy efficiency and stability.     

New Radical Borylation Pathways for Organoboron Synthesis Enabled by Photoredox Catalysis

Radical borylation using N‐heterocyclic carbene (NHC)‐BH₃ complexes as boryl radical precursors has emerged as an important synthetic tool for organoboron assembly. However, the majority of reported methods are limited to reaction modes involving carbo‐ and/or hydroboration of specific alkenes and alkynes. Moreover, the generation of NHC‐boryl radicals relies principally on hydrogen atom abstraction with the aid of radical initiators. A distinct radical generation method is reported, as well as the reaction pathways of NHC‐boryl radicals enabled by photoredox catalysis. NHC‐boryl radicals are generated via a single‐electron oxidation and subsequently undergo cross‐coupling with the in‐situ‐generated radical anions to yield gem‐difluoroallylboronates. A photoredox‐catalyzed radical arylboration reaction of alkenes was achieved using cyanoarenes as arylating components from which elaborated organoborons were accessed. Mechanistic studies verified the oxidative formation of NHC‐boryl radicals through a single‐electron‐transfer pathway.     

Rapid measurements of curcumin from complex samples coupled with magnetic biocompatibility molecularly imprinted polymer using electrochemical detection

Curcumin widely exists in food, and rapid selective and accurate detection of curcumin have great significance in chemical industry. In this experiment, a new magnetic biocompatibility molecularly imprinted polymer was prepared with nontoxic and biocompatible Zein to adsorb curcumin selectively. The polymer has high biocompatibility, good adsorption capacity, and specific adsorption for curcumin. Combined with portable electrochemical workstations, the polymer can be used to detect curcumin rapidly and cost‐effectively. Using curcumin as a template and Zein as the crosslinking agent, the polymers were synthesized on the surface of Fe₃O₄ particles for solid phase extraction. The experimental results showed that the polymer reached large adsorption capacity (32.12 mg/g) with fast kinetics (20 min). The adsorption characteristic of the polymer followed the Langmuir isotherm and pseudo‐second‐order kinetic models. Hexacyanoferrate was used as electrochemical probe to generate signals, and the linear range was 5–200 µg/mL for measuring curcumin. The experimental analysis showed that the polymer was an ideal material for selective accumulation of curcumin from complex samples. This approach has been successfully applied to the determination of curcumin in food samples with electrochemical detection, indicating that this is a feasible and practical technique.     

CuO/Cu2O nanowire array photoelectrochemical biosensor for ultrasensitive detection of tyrosinase

Photoelectrochemical(PEC) biosensors have shown great promise in bioanalysis and diagnostic applications in recent years. In this work, the CuO/Cu_2O nanowire array(CuO/Cu_2O Nanowire) supported on copper foam was prepared as a photocathode for detection of tyrosinase though quinone-chitosan conjugation chemistry method. The in-situ generated quinones that were the catalytic product of tyrosinase acted as electron acceptors, which were captured by the chitosan deposited on the surface of the electrode. Direct immobilization of electron acceptor on the electrode surface improved the photocurrent conversion efficiency and thus sensitivity. The as-prepared biosensor can realize a rapid response in a wide linear range of 0.05 U/mL to 10 U/mL with the detection limit as low as 0.016 U/mL of tyrosinase. The current work provides a new perspective to design and develop highly sensitive and selective PEC biosensor.     

Discussion of the protein characterization techniques used in the identification of membrane protein targets corresponding to tumor cell aptamers

Aptamer is an oligonucleotide chain with specific binding ability to protein and other targets,which is widely used in ma ny fields.Because of its ability to screen the premise of unknown targets,it can be used to discover some novel tumor markers,i.e.,membrane proteins that are specifically highly expressed on the surface of tumor cells.Tumor markers can be used in many fields such as early diagnosis and treatment,and a new type of tumor marker proved to be effective can significantly improve the therapeutic effect of such tumors.However,further characterization of newly acquired membrane proteins is essential for their clinical use as tumor markers.This review first briefly introduced the process of obtaining novel tumor markers from nucleic acid aptamers.Next,the commonly used protein characterization methods could be used as a technical means to identify membrane protein targets corresponding to tumor cell aptamers,to clarify the principles,advantages and disadvantages of various means,and to analyze the most suitable situations for various experimental methods.Finally,the outlook was made and the characterization methods that should be used in such experiments were summarized.     

数码成像比色法测定水样中的总磷

在酸性介质中,磷酸二氢钾与钼酸铵、酒石酸锑钾及抗坏血酸作用,生成蓝色的络合物。随着磷酸二氢钾浓度的增加,溶液颜色加深,其数码成像的RGB值亦随着磷酸二氢钾浓度的增加而增加,由此建立数码成像比色法(DIC)测定水样中总磷的新方法。考察了DIC法的影响因素和最佳反应条件。与钼酸铵分光光度法对照,该方法简单,快速。用于实际水样的测定,相对标准偏差为1.8%~3.4%,回收率为99.7%~102.5%,结果与分光度法一致。     

碱消解-火焰原子吸收光谱法测定土壤中六价铬

建立了碱消解-火焰原子吸收光谱法测定土壤中六价铬的方法.讨论了pH值对六价铬测定的影响.干扰实验的结果表明同等含量的三价铬对六价铬测定无干扰.实验对比了无背景校正、氘灯背景校正、塞曼背景校正三种工作方式,分别对低、中、高三个水平土壤六价铬标准物质进行了测定,结果表明,低含量的土壤样品用塞曼背景校正方式测定的结果更准确,...     

蒙药心舒安中锗的差分脉冲极谱研究

在pH=1.30的H2SO4和3,4-二羟基苯甲醛(DHB)底液中,采用差分脉冲极谱法,测得无机锗的脉冲极谱波.其峰电位为Ep=-0.53V.Ge(Ⅳ)浓度在1.03×10-3-1.04×10-4mol·L-1范围内与峰电流呈线性关系,样品中总锗和无机锗的回收率分别是95.72%和96.43%.