Fabrication and characterization of glutathione-responsive nanoparticles from the disulfide bond-bridged block copolymer

The purpose of this paper is to fabricate novel nanoparticles (NPs) from a single disulfide bond-bridged block copolymer poly(hydroxyethyl methacrylate)-S-S-polycaprolactone (PHEMA-S-S-PCL). The novel biomaterial was synthesized by ring-opening polymerization and reversible addition–fragmentation chain transfer polymerization. The cargo-free NPs were fabricated with the solvent evaporation method, and studies on NPs' characterizations were carried out. The hydrogen nuclear magnetic resonance (¹H NMR) and Fourier transform infrared spectroscopy spectra confirmed the synthesis of PHEMA-S-S-PCL copolymer. Thermo-gravimetric analysis curves indicated that the obtained PHEMA-S-S-PCL copolymer had good thermostability. Transmission electron microscopy and dynamic light scatter results suggested that the cargo-free NPs were in round shapes with an average diameter of 103.6 ± 0.12 nm. The low critical micelle concentration of cargo-free NPs (7.9 × 10^?4 mg/ml) indicated that these NPs would keep their spherical shapes after being attenuated by abundant liquid (e.g., blood or body fluid). Furthermore, these NPs showed high stability at the presence of bovine serum albumin. Therefore, it could be speculated that these NPs would not be absorbed by proteins in blood, and they could be used as a candidate carrier for drug delivery.     

Cytotoxicity of Amino-BODIPY Modulated via Conjugation with 2-Phenyl-3-Hydroxy-4(1H)-Quinolinones

The combination of cytotoxic amino-BODIPY dye and 2-phenyl-3-hydroxy-4(1H)-quinolinone (3-HQ) derivatives into one molecule gave rise to selective activity against lymphoblastic or myeloid leukemia and the simultaneous disappearance of the cytotoxicity against normal cells. Both species′ conjugation can be realized via a disulfide linker cleavable in the presence of glutathione characteristic for cancer cells. The cleavage liberating the free amino-BODIPY dye and 3-HQ derivative can be monitored by ratiometric fluorescence or by the OFF-ON effect of the amino-BODIPY dye. A similar cytotoxic activity is observed when the amino-BODIPY dye and 3-HQ derivative are connected through a non-cleavable maleimide linker. The work reports the synthesis of several conjugates, the study of their cleavage inside cells, and cytotoxic screening.     

Abnormal adsorption behavior of dimethyl disulfide on gold surfaces

Adsorption of dimethyl disulfide (DMDS) on gold colloidal nanoparticle surfaces has been examined to check its binding mechanism. Differently from previous results, DMDS molecules adsorbed on the gold surface at high concentration showed the S–S stretching band at 500 cm⁻¹ in surface-enhanced Raman scattering (SERS) spectra, which indicates the presence of intact adsorption of DMDS molecules. However, it was found that the S–S bond of disulfides was easily cleaved on the gold surface at low concentration. These behaviors were not observed for diethyl disulfide (DEDS) or diphenyl disulfide (DPDS). Our results indicate that DMDS molecules with the shortest alkyl chains on the gold surface can be inserted into self-assembled monolayers (SAMs) without the S–S bond cleavage during self-assembly due to insufficient lateral van der Waals interaction and the low adsorption activity of disulfides, whereas DEDS with longer alkyl chains or DPDS with the weak disulfide bond dissociation energy would not. These unusual DMDS adsorption behaviors were examined by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). We also compared the bonding dissociation energy of the S–S bonds of various disulfides by means of a density functional theory (DFT) calculation.     

Cu/MoS2的熔盐电解法制备及其在碱性条件下析氢反应性能的提高

通过熔盐电解法并掺杂过渡金属Cu制备2种不同纳米结构的Cu/MoS_2。采用涂敷法制备工作电极,通过X射线衍射(XRD)、透射电子显微镜(TEM)、能量散射X射线谱(EDS)、扫描电子显微镜(SEM)、选区电子衍射(SAED)以及各种电化学手段验证了其结构和性能。结果表明,纳米片状Cu/MoS_2在碱性溶液(1 mol·L~(-1)KOH)中表现出优异的析氢催化性能:在电流密度为10 mA·cm~(-2)时过电位为199.6 mV,Tafel斜率为59 mV·dec~(-1),双电层电容为26.1 mF·cm~(-2),等效电荷转移电阻为12.4Ω,具有较为良好的电化学耐久性和稳定性。     

二硫化锡纳米片阻变存储器的制备与性能

采用水热法合成了尺寸为50~100 nm的二硫化锡纳米片,并首次以二硫化锡作为阻变层材料的阻变存储器（Cu/PMMA/SnS₂/Ag,PMMA=聚甲基丙烯酸甲酯）,对其阻变性能进行了研究。结果表明： Cu/PMMA/SnS₂/Ag阻变存储器的开关比约10⁵,耐受性2.7×10³。在上述2项性能指标达到较优水平的同时,开态与关态电压分别仅约为0.28与-0.19 V。     

Tuning Lanthanide Reactivity Towards Small Molecules with Electron‐Rich Siloxide Ligands

The synthesis, structure, and reactivity of stable homoleptic heterometallic LnL₄K₂ complexes of divalent lanthanide ions with electron‐rich tris(tert‐butoxy)siloxide ligands are reported. The [Ln(OSi(OtBu)₃)₄K₂] complexes (Ln=Eu, Yb) are stable at room temperature, but they promote the reduction of azobenzene to yield the KPhNNPh radical anion as well as the reductive cleavage of CS₂ to yield CS₃^2? as the major product. The Eu^III complex of the radical anion PhNNPh is structurally characterized. Moreover, [Yb(OSi(OtBu)₃)₄K₂] can reduce CO₂ at room temperature. Release of the reduction products in D₂O shows the quantitative formation of both oxalate and carbonate in a 1:2.2 ratio. The bulky siloxide ligands enforce the labile binding of the reduction products providing the opportunity to establish a closed synthetic cycle for the Yb^II‐mediated CO₂ reduction. These studies show that the presence of four electron‐rich siloxide ligands renders their Eu^II and Yb^II complexes highly reactive.     

二氧化锰纳米管模拟氧化酶的性能、抑制剂及其对Pb2+的测定

采用简便的水热法,获得了具有氧化酶催化特性的二氧化锰纳米管,研究了其对氧气(O2)氧化3,3',5,5'-四甲基联苯二胺(TMB)发生显色反应的催化性能,重点考察了常见金属离子对其活性的抑制作用。结果表明,能与MnO2表面发生特异性吸附络合作用的Pb2+的抑制作用最为显著。基于该抑制作用,建立了针对铅离子的高灵敏、快速检测新方法。结果显示,铅的线性范围为1.0×10-7~1.0×10-3 mol/L,检出限为3.0×10-8 mol/L。     

新型含二硫键的环肽的合成

本实验设计从Boc-Glu-OH,Boc-Asp-OH的两个羧基出发,最后通过I2氧化两个半胱氨酸的巯基生成二硫键,得到一类新型含二硫键的环肽,该环肽通过1H NMR,MS等确定了其结构.