Improving gene transfection efficiency of highly branched poly(β-amino ester)s through the in-situ conversion of inactive terminal groups

Highly branched poly(β-amino ester)s(HPAEs)have emerged as a safe and efficient type of non-viral gene delivery vectors.However,the presence of inactive terminal secondary amine groups compromises their gene transfection capability.In this study,HPAEs with similar topological structures and chemical compositions but varying numbers of terminal secondary 4-amino-1-butanol(S4)and secondary/tertiary 3-morpholinopropylamine(MPA)groups were synthesized.The results demonstrate that an increased number of secondary/tertiary MPA groups in-situ significantly enhances the DNA binding capability of HPAEs,leading to the formation of smaller HPAE/DNA polyplexes with higher zeta potential,ultimately resulting in superior gene transfection efficiency in bladder epithelial cells.This study establishes a sim-ple yet effective strategy to maximize the gene transfection potency of HPAEs by converting the inactive terminal groups in-situ without the need for complex modifications to their topological structure and chemical composition.

Hydrophobic terminal group of surfactant initiating micellization as revealed by^1H NMR spectroscopy

The critical aggregation concentration（CAC） of four with three kinds of conventional surfactants, namely,two cationic surfactants [hexadecyltrimethyl ammonium bromide（CTAB） and tetradecyltrimethyl ammonium bromide（TTAB）], one anionic surfactant [sodium dodecyl sulfate（SDS）], and a nonionic surfactant [Triton X-100（TX-100）], were determined by variation of ^1H chemical shifts with surfactant concentrations. Results show that the CAC values of protons at different positions of the same molecule are different, and those of the terminal methyl protons are the lowest, respectively, which suggests that the terminal groups of the alkyl chains aggregates first during micellization. Measurement of the transverse relaxation time（T2） of different protons in SDS also show that the terminal methyl protons start to decrease with the increase in concentration first, which supports the above mentioned tendency.

Studies on the effect of opposite terminal groups in phenylpolyenic conjugative systems

Seven homologous series p-A=B-C_6H_4(CH=CH)_nX=Y (A=B: NO_2, X=Y: CHO, COMe, CN, NO_2; A=B: CN, X=Y: CHO, CN; A=B: H, X=Y: NO_2) were synthesized, the effect of opposite terminal groups in phenylpolyenic conjugative systems has been studied by means of UV, XPS, ^(13) C NMR and quantum chemical calculation. The results show that: 1. There exists the effect of opposite terminal groups exists in phenylpolyenic and other aromatic conjugative systems. 2. When A=B and X=Y are the same, the group (-X=Y) connected at polyenic chain is a terminal group, while the other is an opposite terminal group. When the two groups are different, the one with weaker conjugative power plays the role of the opposite terminal group. 3. The effect of opposite terminal groups increases successively in the order of CN, COMe, CHO, NO_2 and can be quantita- tively described with substitute equivalent △N_s. Theλ_(max) of compound containing an opposite terminal group can be calculated by the homologous equation 10^(-4) =a+b/(1/2)^(2/N＇^(-S)_a), most of the calculated values are in agreement with experiment results.

MXene terminating groups=O,–F or–OH,–F or=O,–OH,–F,or=O,–OH,–Cl?

MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.

Recent advances and perspectives in MXene-based cathodes for aqueous zinc-ion batteries

Aqueous zinc-ion batteries(AZIBs)show great potential for applications in grid-scale energy storage,given their intrinsic safety,cost effectiveness,environmental friendliness,and impressive electrochemical performance.However,strong electrostatic interactions exist between zinc ions and host materials,and they hinder the development of advanced cathode materials for efficient,rapid,and stable Zn-ion storage.MXenes and their derivatives possess a large interlayer spacing,excellent hydrophilicity,outstanding electronic conductivity,and high redox activity.These materials are considered“rising star”cathode candidates for AZIBs.This comprehensive review discusses recent advances in MXenes as AZIB cathodes from the perspectives of crystal structure,Zn-storage mechanism,surface modification,interlayer engineering,and conductive network design to elucidate the correlations among their composition,structure,and electrochemical performance.This work also outlines the remaining challenges faced by MXenes for aqueous Zn-ion storage,such as the urgent need for improved toxic preparation methods,exploration of potential novel MXene cathodes,and suppression of layered MXene restacking upon cycling,and introduces the prospects of MXene-based cathode materials for high-performance AZIBs.

Recent advances in titanium carbide MXene-based nanotextures with influential effect of synthesis parameters for solar CO_(2)reduction and H_(2)production:A critical review

Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental concerns.Recently,titanium carbide(Ti_(3)C_(2))MXenes have been recognized as promising cocatalysts based on their metallic conductivity,excessive active reaction sites,and enlarged surface area.The current review focuses on the properties and applications of Ti_(3)C_(2)MXenes useful in the field of photocatalysis.More specifically,surface modification of Ti_(3)C_(2)MXenes by varying synthesis parameters to get pure materials and also composites with the role of functional groups towards solar energy conversion applications is highlighted in this review.The effect of etching and oxidizing pathways to get an efficient cocatalyst has been discussed in detail.Considering the significant effect of parameters,optimum synthesis conditions such as etchant type,concentration,time and type of intercalant in both the Ti_(3)C_(2)synthesis approaches for improved photoactivity are discussed.Additionally,the surface modification of Ti_(3)C_(2)through oxidation for TiO2growth on its surface is deliberated with a detailed discussion on etchant type,concentration,etching time,and environmental factors.The optimum oxidation condition,including temperature,time,and environment for thermal treatment of Ti_(3)C_(2),were also included.Lastly,the review summarizes the conclusion and future perspectives for solar energy conversion applications.

Tailoring molecular termination for thermally stable perovskite solar cells

Interfacial engineering has made an outstanding contribution to the development of high-efficiency perovskite solar cells(PSCs).Here,we introduce an effective interface passivation strategy via methoxysilane molecules with different terminal groups.The power conversion efficiency(PCE)has increased from 20.97%to 21.97%after introducing a 3-isocyanatopropyltrimethoxy silane(IPTMS)molecule with carbonyl group,while a trimethoxy[3-(phenylamino)propyl]silane(PAPMS)molecule containing aniline group deteriorates the photovoltaic performance as a consequence of decreased open circuit voltage.The improved performance after IPTMS treatment is ascribed to the suppression of non-radiative recombination and enhancement of carrier transportation.In addition,the devices with carbonyl group modification exhibit outstanding thermal stability,which maintain 90%of its initial PCE after 1500 h exposure.This work provides a guideline for the design of passivation molecules aiming to deliver the efficiency and thermal stability simultaneously.

Synthesis of carbon nitride in moist environments:A defect engineering strategy toward superior photocatalytic hydrogen evolution reaction

Intimate understanding of the synthesis-structure-activity relationships is an accessible pathway to overcome the intrinsic challenges of carbon nitride(g-C_(3)N_(4))photocatalysts.This work looks in the effects of humidity of the synthesis process to the morphology,chemical structure,band structure as well as the photocatalytic activity of g-C_(3)N_(4) materials.Four g-C_(3)N_(4) samples were prepared by heating melem in four gas environments:dry Ar,dry Air,moist Ar and moist Air.The photocatalytic activity measurements revealed that the samples synthesized in moist inert and oxidic gases environments displayed 20 and 10 times the photocata lytic H_(2) evolution activity of the samples synthesized in dry inert and oxidic gases environments,respectively.The reasons for this remarkable variety in photocata lytic activities had been through investigated.After all,the terminations of the carbon vacancies were identified as the dominant factor in enhancing H_(2) evolution performance.The work here thus demonstrating an example of defect engineering.

SYNTHESIS OF STYRYL-CAPPED POLYPROPYLENE via METALLOCENE-MEDIATED COORDINATION POLYMERIZATION: APPLY TO POLYPROPYLENE MACROMOLECULAR ENGINEERING

In this paper, we review our recent progress in the synthesis and application of styryl-capped polypropylene （PP-t- St）, an excellent reactive polyolefin that is both convenient and efficient in synthesis and facile and versatile in application for preparing advanced polypropylene materials via macromolecular engineering. The synthesis of PP-t-St is made possible by a unique chain transfer reaction coordinated by a bis-styrenic molecule, such as 1,4-divinylbenzene （DVB） and 1,2-bis（4- vinylphenyl）ethane （BVPE）, and hydrogen in typical C2-symmetric metallocene （e.g. rac-Me2Si（2-Me-4-Ph-Ind）2ZrC12, in association with methylaluminocene, MAO） catalyzed propylene polymerization. The regio-selective 2,1- insertion of the styrenic double bond in DVB or BVPE into the overwhelmingly 1,2-fashioned Zr-PP propagating chain enables substantial dormancy of the catalyst active site, which triggers selective hydrogen chain transfer that, with the formed Zr-H species ultimately saturated by the insertion of propylene monomer, results in an exclusive capping of the afforded PP chains by styryl group at the termination end. With a highly reactive styryl group at chain end, PP-t-St has been used as a facile building block in PP macromolecular engineering together with the employment of state-of-the-art synthetic polymer chemistry to fabricate broad types of new polypropylene architectures.

Binuclear Ruthenium Complexes with Benzo[1,2-b;4,5-b＇]- dithiophene Analogues as Bridge Ligands： Syntheses, Characterization and Notable Difference on Electronic Coupling

Diruthenium ethynyl complexes 1--3 （1： 1,5-dithia-s-indacene-4,8-dione; 2： 4,8-diethoxybenzo[1,2-b：4,5- b＇]dithiophene; 3： 4,8-didodecyloxybenzo[1,2-b：4,5-b＇]dithiophene） have been synthesized by incorporating the re- spective conjugated heterocyclic spacer and characterized by NMR and elemental analysis. The effects of bridge ligands＇ properties on electronic coupling between redox-active ruthenium terminal groups were investigated by electrochemistry, UV/vis/near-IR and IR spectroelectrochemistry combined with density functional theory （DFT） and time-dependent DFT calculations. Electrochemistry results indicated that complexes 1--3 exhibit two fully re- versible oxidation waves, and complexes 2 and 3 with electron-rich and π-conjuagted bridge ligands are character- ized by excellent electrochemical properties. Furthermore, the larger v（C≡C） separation from the IR spectroelec- trochemical results of 2 and 3 and the intense NIR absorption features of singly oxidized species 2＋ and 3＋ re- vealed that their molecular skeletons have superior abilities to delocalize the positive charge. The spin density dis- tribution from DFT calculations proved the conclusions of this study.

Low friction in self-mated silicon carbide tribosystem using nanodiamond as lubricating additive in water

Nanodiamond particles(NDPs)have been considered as a potential lubricant additive to various tribological applications,such as water lubrication systems.In this study,the tribological properties of silicon carbide(SiC)lubricated by NDPs dispersed in water are investigated utilizing the ball-on-disk tribometer.It is found that the slight addition of NDP to water(i.e.,0.001 wt%)can distinctly accelerate the running-in process,which is necessary to achieve a friction coefficient(μ)as low as 0.01.This study also discusses two NDP functional terminations—hydroxyl and carboxyl.It is demonstrated that the use of carboxyl-terminated NDP over a wide range of concentration(0.001 wt%-1 wt%)yields a low friction force.In contrast,the ideal effective concentration of hydroxyl-terminated NDP is considerably limited because agglomeration in this material is more probable to occur than in the former.Meanwhile,when utilizing NDPs,the input friction energy(P_(in),defined as the product of sliding speed and applied load)is found to have an essential function.Several sliding tests were implemented at various P_(in) values(50-1,500 mW)using carboxyl-terminated water-dispersed NDPs.It was observed that theμand wear decreased with increasing P_(in) when 200 mW<P_(in)<1,500 mW.However,when P_(in)<200 mW,low friction with high wear occurs compared with the resulting friction and wear when pure water is used.