Disulfide-crosslinked Poly(L-glutamic acid) Grafted Mesoporous Silica Nanoparticles and Their Potential Application in Drug Delivery

Poly(L-glutamic acid)(PLGA) was grafted onto the surface of mesoporous silica nanoparticles(MSN) via the ring opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride(BLG-NCA) and its subsequent deprotection of benzyl groups. The PLGA chains were cross-linked with cystamine, and thus forming a type of redox responsive drug delivery system(MSN-cPLGA). The structures were characterized by Fourier transform infrared spectrometry(FTIR), transmission electron microscopy(TEM) and energy disperse spectrometry(EDS), demonstrating that disulfide groups existed on the surfaces of MSN-cPLGA particles. The thermal gravimetric analysis(TGA) results show that the PLGA mass fraction is about 33.4% in the MSN-cPLGA hybrid. The in vitro drug release experiments showed that the MSN-cPLGA hybrid can realize the controlled release of model drugs(5-fluorouracil) in response to redox environment. Even 0.1 mmol/L dithiothreitol(DTT) can accelerate the drug release speed, and a concentration of 10.0 mmol/L DTT is higher enough to trigger the open of cross-linked PLGA network so as to realize rapid release of drugs. All the results demonstrate that the cross-linked PLGA chains on the surface of MSN could act as efficient gatekeepers to control the on-off of the pores, showing potential application in drug delivery system.     

Strong convergence theorems for infinite family of relatively quasi nonexpansive mappings and systems of equilibrium problems

In this paper, we construct a new iterative scheme by hybrid method for approximation of common element of set of common fixed points of countably infinite family of relatively quasi-nonexpansive mappings and set of common solutions to a system of equilibrium problems in a uniformly convex and uniformly smooth real Banach space using the properties of generalized f-projection operator. Then, we prove strong convergence of the scheme to a common element of the two sets. Furthermore, we apply our results to solve convex minimization problem. Our results extend important recent results.     

Syntheses,structures and properties of four organic–inorganic hybrid nicotinate-bridging rare-earth-containing phosphotungstates

Four novel organic–inorganic hybrid nicotinate-bridging dimeric rare-earth (RE)-containing phosphotungstates [H₂N(CH₃)₂]₈[RE(H₂O)(NA)(α-HPW₁₁O₃₉)]₂·24H₂O (RE = Ho^III for 1, Er^III for 2, Tb^III for 3, Dy^III for 4; HNA = nicotinic acid) have been synthesized from the reaction of trivacant Keggin precursor Na₉[α-PW₉O₃₄]∙16H₂O, RE(NO₃)₃·6H₂O, HNA by employing dimethylamine hydrochloride as organic solubilizing agent in the conventional aqueous solution system, which have been further characterized by elemental analyses, IR spectra, thermogravimetric analyses and single-crystal X-ray diffraction. Structural analysis indicates that the hybrid dimeric {[RE(H₂O)(NA)(α-HPW₁₁O₃₉)]₂}⁸⁻ polyoxoanion in 1–4 can be considered as two head-to-head mono-RE-containing Keggin [RE(H₂O)(NA)(α-HPW₁₁O₃₉)]⁴⁻ subunits bridged by two (η²,μ-1,1)-nicotinate linkers, which stands for the first organic–inorganic hybrid RE-containing phosphotungstates functionalized by nicotinate ligands. What's more, the solid-state photoluminescence properties and lifetime decay behaviors of 1–4 have been measured at room temperature and their photoluminescence spectra display the characteristic emission bands of corresponding trivalent RE cations.     

Synthesis of silica-polystyrene core-shell nanoparticles via surface thiol-lactam initiated radical polymerization

This paper reports the synthesis of structurally well-defined silica-polystyrene (SiO₂@PS) hybrid nanoparticles using a thiol-lactam-initiated, radical-polymerization technique. The surface of silica particles, 80 nm in size, were functionalized with (3-mercaptopropyl) trimethoxysilane and used as seeds in the polymerization of styrene in the presence of butyrolactam. ¹H nuclear magnetic resonance and X-ray photoelectron spectroscopy showed that the thiol groups on the SiO₂ surface could initiate polymerization with the aid of butyrolactam. Transmission electron microscopy showed that the hybrid particles had uniform core-shell morphologies. The molecular weight of grafted PS increased with increasing polymerization time.     

A pair of new enantiomeric hybrid phthalide–adenines with a rare 5-oxa-1-azaspiro[3,4]octane moiety and two pairs of new enantiomeric hybrid paraethyl phenol–adenines from Ligusticum chuanxiong

Three pairs of new enantiomeric adenine alkaloids, (+)/(?)-liguadenines A–C [(+)/(?)-1–3], were isolated from the rhizome of Ligusticum chuanxiong Hort. The structures and absolute configurations of these compounds were determined using spectroscopic data, single-crystal X-ray diffraction, and electronic circular dichroism analyses. To the best of our knowledge, compounds (+)-1 and (?)-1 are the first hybrid phthalide–adenines to be ever reported. The linkage between the phthalide and adenine units in these compounds forms a rare 5-oxa-1-azaspiro[3,4]octane moiety. Analyses of the anti-inflammatory activities of the isolated compounds show that (+)/(?)-1 and (+)-3 exhibit significant inhibitory activity against LPS-induced TNF-α and IL-6 production in RAW264.7 cells. RT-qPCR analysis confirms that the most active compound, (+)-3, exerts anti-inflammatory activity by downregulating the mRNA expressions of TNF-α and IL-6 in the cells.     

Glass Formation in Hybrid Organic-Inorganic Perovskites

Crystalline materials have governed the development of hybrid organic-inorganic perovskites (HOIPs), giving rise to a variety of fascinating applications such as solar cells and optoelectronic devices. With increasing interest in non-crystalline systems, the glassy state of HOIPs has recently been identified. Here, the basic building blocks of crystalline HOIPs appear to be retained, though their glasses lack long-range periodic order. The emerging family of glasses formed from HOIPs exhibits diverse properties, complementary to their crystalline state. This mini review describes the chemical diversity of both three-dimensional and two-dimensional crystalline HOIPs and demonstrates how glasses are produced from these materials. Specifically, current achievements in melt-quenched glasses formed from HOIPs are highlighted. We conclude with our perspective on the future of this new family of materials.     

Mathematical modelling of a hydraulic accumulator for hydraulic hybrid drives

ABSTRACT

Hydraulic accumulators are used as energy storages in a wide area of applications. In particular, in automotive hybrid drive-trains, this type of energy storage is an interesting alternative to today’s common strategies like chemical batteries or flywheels. This article deals with the mathematical modelling of a hydraulic accumulator for passenger vehicles, which comprises a carbon fibre reinforced plastic (CFRP) body and aluminium piston. The thermodynamical behaviour of the oil and gas as well as the interaction with the CFRP body is investigated in detail. Starting from a complex model, two models of reduced complexity are derived. The validation of these models with measurement data from a test drive with a prototype series hydraulic hybrid drive-train proves their high accuracy.     

Syntheses, structures, characterizations and charge-density matching of novel amino-templated uranyl selenates

Five hybrid organic-inorganic uranyl selenates have been synthesized, characterized and their structures have been determined. The structure of (C₂H₈N)₂[(UO₂)₂(SeO₄)₃(H₂O)] (EthylAUSe) is monoclinic, P2₁, a=8.290(1), b=12.349(2), c=11.038(2) Å, β=104.439(4)°, V=1094.3(3) Å³, Z=2, R₁=0.0425. The structure of (C₇H₁₀N)₂[(UO₂)(SeO₄)₂(H₂O)]H₂O (BenzylAUSe) is orthorhombic, Pna2₁, a=24.221(2), b=11.917(1), c=7.4528(7) Å, V=2151.1(3) Å³, Z=4, R₁=0.0307. The structure of (C₂H₁₀N₂)[(UO₂)(SeO₄)₂(H₂O)](H₂O)₂ (EDAUSe) is monoclinic, P2₁/c, a=11.677(2), b=7.908(1), c=15.698(2) Å, β=98.813(3)°, V=1432.4(3) Å³, Z=4, R₁=0.0371. The structure of (C₆H₂₂N₄)[(UO₂)(SeO₄)₂(H₂O)](H₂O) (TETAUSe) is monoclinic, P2₁/n, a=13.002(2), b=7.962(1), c=14.754(2) Å, β=114.077(2)°, V=1394.5(3) Å³, Z=4, R₁=0.0323. The structure of (C₆H₂₁N₄)[(UO₂)(SeO₄)₂(HSeO₄)] (TAEAUSe) is monoclinic, P2₁/m, a=9.2218(6), b=12.2768(9), c=9.4464(7) Å, β=116.1650(10)°, V=959.88(12) Å³, Z=2, R₁=0.0322. The inorganic structural units in these compounds are composed of uranyl pentagonal bipyramids and selenate tetrahedra. In each case, tetrahedra link bipyramids through vertex-sharing, resulting in chain or sheet topologies. The charge-density matching principle is discussed relative to the orientations of the organic molecules between the inorganic structural units.     

Synthesis and Characterization of a Two‐Dimensional Zinc Phosphite,Zn3(tren)(HPO3)3·xH2O (x ≈ 0.5; tren = tris(2‐aminoethyl)amine)

A new zinc phosphite with the formula Zn₃(tren)(HPO₃)₃·xH₂O (x≈0.5) has been synthesized under hydrothermal conditions and characterized by FTIR, elemental analysis, powder X‐ray diffraction, single‐crystal X‐ray diffraction, thermogravimetric analysis and its fluorescent spectrum. The compound crystallizes in the triclinic system, space group (No.2), a = 10.1188(9) Å, b = 10.4194(9) Å, c = 10.5176(9) Å, α = 60.763(2)°, β = 70.6150(10)°, γ = 80.725(2)°, V = 912.77(14) ų, Z = 2. The structure consists of double crankshaft chains, which are linked by Zn‐O‐P bonds to form 8‐ and 12‐membered channels along the [100] direction. The claw‐like Zn‐centered complexes of Zn(N₄C₆H₁₈) as the supported templates, hang into the 12‐MR channels through Zn‐O‐P linkages with framework.     

A Novel Hybrid Nano‐composite Grafted Electrochemically Reduced Graphene Oxide Based Sensor for Sensitive Determination of Efavirenz

A novel, facile fabrication, based on electrochemically reduced graphene oxide (ErGO), grafted with Pt nanoparticles and Nafion hybrid nano‐composite (ErGO‐Pt/Nafion) on the surface of edge plane pyrolytic graphite (EPPG) has been reported. The fabricated sensor has been used for the sensitive and selective determination of efavirenz (EFZ), a well‐known drug for HIV infections. The ErGO‐Pt/Nafion film was characterized by Field Emission Scanning Electron Microscopy (FE‐SEM), Energy‐dispersive X‐ray spectrometry (EDS) and Electrochemical Impedance Spectroscopy (EIS). The experimental results reveal that the modified sensor displays an excellent electrocatalytic activity towards the oxidation of EFZ and exhibits a large linear dynamic relationship in the range of 0.05 μM to 150 μM, with a detection limit of 1.8 nM. Practical utility of the developed sensor has been demonstrated by determining the EFZ in biological fluids and pharmaceutical samples and a low detection limit with high sensitivity observed makes it valuable for the clinical diagnosis.