Incorporation of Polyoxometalates Into Polystyrene Latex by Supramolecular Encapsulation and Miniemulsion Polymerization

Submicrometer polystyrene (PS) latex doped with functional polyoxometalates (POMs) has been elaborated via two steps. The first step is the electrostatic encapsulation of POMs by polymerizable surfactants through the replacement of counterions, forming the supramolecular complexes which are organic compatible. And the second step is the incorporation of the complexes into PS latex chemically by miniemulsion polymerization. TEM images indicate that POMs are evenly dispersed in the hybrid latex, and spectral characterizations demonstrate that the properties of POMs are well retained, leading to the functional features of polymer latex, such as luminescence and coloration. Furthermore, the supramolecular encapsulation and the hydrophobic latex matrix provide an effective protection to POMs, which greatly enhances their stability against the ambient acid or basic environment.

     

胰岛封装技术及其在胰岛移植中的应用

随着全球糖尿病患者人数逐年增长,临床上亟需一种行之有效的糖尿病治疗方案。胰岛移植可通过植入具有正常功能的胰岛以替代患者体内功能受损的胰岛,从而维持正常血糖水平,有望发展为理想的糖尿病治疗方法。然而,胰岛供体资源短缺,且移植后长期服用免疫抑制剂不仅产生诸多不良反应甚至会有致癌风险。以上瓶颈极大限制了胰岛移植的临床应用。采用天然高分子、合成高分子、无机化合物等生物材料对胰岛进行封装,营造免疫隔离微环境,避免宿主免疫细胞与植入胰岛直接接触,可有效抑制免疫排斥反应。免疫隔离的同时,胰岛的封装不影响胰岛素、葡萄糖、氧气等胰岛必需或输出关键分子的交换,同时确保移植胰岛的正常生理活性及精准控制血糖水平的能力。本文综述了胰岛封装的研究现状,常用材料及设计策略,并初步展望其应用前景。     

Spatially Controlled Molecular Encapsulation in Natural Pine Pollen Microcapsules

The loading of multiple drugs into a single carrier is an effective advanced clinical therapeutic for various diseases. Here, by exploiting the architectural features of natural pine pollen from Pinus massoniana, the spatially controlled encapsulation of two types of molecules in distinct compartments of a single microparticulate carrier is demonstrated. By simple vacuum and passive loading, diverse molecules such as proteins, organic dyes, and a drug are effectively encapsulated into the pollen microcapsule in binary fashion. This technique represents an advancement toward the use of natural pollen grains as a multifunctional molecular vehicle for functional drug delivery systems and innovative theranostic microdevices.     

GaN基白光LED可靠性研究与失效分析

针对LED样品检测中的样品短路失效、LED光源黑化、光通量下降和芯片表面通孔异常现象,采用金相切片、机械微操、静电测试等方式结合扫描电镜和能谱仪（EDS）等表征手段对失效机制进行了分析,揭示了LED失效原因。包括镀层银离子与杂质硫离子导致光源黑化;芯片抗静电电压低,部分样品发生静电击穿;失效芯片通孔下面的Ni-Sn共晶层存在大量空洞,使得复杂结构的芯片通孔应力不均,样品工作时芯片表面开裂破碎,从而导致PN结短路失效;封装胶中残存的杂质离子腐蚀芯片负电极导致电极脱落而出现漏电、光衰和死灯等现象。     

Encapsulation of inorganic particles via miniemulsion polymerization. I. Dispersion of titanium dioxide particles in organic media using OLOA 370 as stabilizer

The dispersion of hydrophilic and hydrophobic titanium dioxide (TiO₂) particles in organic media (styrene and cyclohexane) was studied to evaluate the effect of dispersion quality (i.e., size and stability) on the encapsulation efficiencies of subsequent miniemulsion polymerizations. Through screening studies of various block copolymers, OLOA 370 (polybutene–succinimide pentamine) was chosen as the stabilizer for detailed dispersion studies on both types of TiO₂ particles. As a result of strong interactions between the amine end group of the OLOA 370 stabilizer and the hydroxyl groups on the surface of the hydrophilic TiO₂ particles, a good dispersion stability and small particle size (D_v = 39–45 nm) was obtained using 1.0 wt % stabilizer and 20 min of sonification. The dispersions of the hydrophobic TiO₂ particles resulted in a larger average particle size (D_v = 60 nm) and poorer stability. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4419–4430, 2000     

Front Cover: A Highly Sterically Congested Bis-Zinc-Porphyrin Containing a Single Buta-1,3-diyne Linkage: From a Serendipitous Finding to Supramolecular Encapsulation (Eur. J. Org. Chem. 35/2023)

A unique example of a bis-zinc-porphyrin chemical system in which both macrocycles are covalently connected with a single, short buta-1,3-diyne linkage placed at the ortho sites of the meso phenyl rings is presented. This dimeric compound resulted from an homo-coupling side-reaction taking place during a copper-catalyzed click reaction between an alkyne porphyrin and 2-azidopyridine derivatives. Its unexpected formation was rationalized by control experiments and an improved synthesis was achieved under copper-catalyzed Glaser-Hay coupling reaction conditions. This highly sterically congested bis-zinc-porphyrin derivative behaved as a supramolecular host for encapsulating ditopic molecular guests such as 1,4-diazabicyclo[2.2.2]octane (DABCO) with association constant K_1.1 in the order of 10⁶ M⁻¹. This value is comparable to current systems that typically feature several connecting linkages between the two zinc-porphyrin sites resulting in (supra)molecular cages ensuring a high pre-organization. As such, the requirements to take benefit from supramolecular encapsulation can be reduced to a highly rigid, minimal covalent linkage of four atoms between zinc-porphyrins as herein described.     

Encapsulation of magnetic self-assembled systems in thermoreversible gels

We describe two different ways of encapsulating within the fibrils of thermoreversible polymer gels the filaments of a supermolecular polymer formed by self-assembly of a bicopper complex. Heterogeneous nucleation is brought about with gels made from isotactic poly(styrene) while compound formation occurs with gels made from poly(hexyl isocyanate). These ways depend upon the interaction between the wings of the supermolecular polymer and the side groups of the polymer. In all cases, the filaments retain their 1-D structure. Preliminary results from magnetic susceptibility measurements show a striking difference between the pure and the encapsulated supermolecular polymer.     

Ultra-small PtNi bimetallic encapsulated in silicalite-1 zeolite with fine-tuned surface acidity for selective conversion of levulinic acid

Exploration of levulinic acid (LA) hydrogenation to γ-valerolactone (GVL) contributes to the conversion from carbohydrates to valuable fuels and chemicals. Here, we obtained a series of ultra-small PtNix bimetallic composite catalysts encapsulated in silicalite-1 zeolite (S-1) via a one-pot synthesis strategy protected by tetra(p-carboxyphenyl)porphyrin (TCPP) ligands. The catalytic results showed that PtNi₃@S-1 (TCPP) exhibited the most active catalytic performance (95.7% LA conversion and 93.8% GVL selectivity) under optimized conditions. The characterization results indicate that ligand modification and bimetallic synergy play an important role in enhancing the catalytic activity. The introduction of TCPP provides a guarantee for the homogeneous encapsulation of PtNi₃ in S-1 zeolite at sub-nanometer size. The electronic interaction of PtNi bimetallic, high dispersibility of active components, improved surface acidity and excellent stability co-contribute to the satisfactory hydrogenation activity.     

Cage-size effects on the encapsulation of P2 by fullerenes

The classic pnictogen dichotomy stands for the great contrast between triply bonding very stable N₂ molecules and its heavier congeners, which appear as dimers or oligomers. A banner example involves phosphorus as it occurs in nature as P₄ instead of P₂, given its weak π-bonds or strong σ-bonds. The P₂ synthetic value has brought Lewis bases and metal coordination stabilization strategies. Herein, we discuss the unrealized encapsulation alternative using the well-known fullerenes' capability to form endohedral and stabilize otherwise unstable molecules. We chose the most stable fullerene structures from C_n (n = 50, 60, 70, 80) and experimentally relevant from C_n (n = 90 and 100) to computationally study the thermodynamics and the geometrical consequences of encapsulating P₂ inside the fullerene cages. Given the size differences between P₂ and P₄, we show that the fullerenes C₇₀–C₁₀₀ are suitable cages to side exclude P₄ and host only one molecule of P₂ with an intact triple bond. The thermodynamic analysis indicates that the process is favorable, overcoming the dimerization energy. Additionally, we have evaluated the host-guest interaction to explain the origins of their stability using energy decomposition analysis.