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。     

Optimising the Polyphenolic Content and Antioxidant Activity of Green Rooibos (Aspalathus linearis) Using Beta-Cyclodextrin Assisted Extraction

Antioxidant activity associated with green rooibos infusions is attributed to the activity of polyphenols, particularly aspalathin and nothofagin. This study aimed to optimise β-cyclodextrin (β-CD)-assisted extraction of crude green rooibos (CGRE) via total polyphenolic content (TPC) and antioxidant activity assays. Response surface methodology (RSM) permitted optimisation of β-CD concentration (0–15 mM), temperature (40–90 °C) and time (15–60 min). Optimal extraction conditions were: 15 mM β-CD: 40 °C: 60 min with a desirability of 0.985 yielding TPC of 398.25 mg GAE·g⁻¹, metal chelation (MTC) of 93%, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging of 1689.7 µmol TE·g⁻¹, ferric reducing antioxidant power (FRAP) of 2097.53 µmol AAE·g⁻¹ and oxygen radical absorbance capacity (ORAC) of 11,162.82 TE·g⁻¹. Aspalathin, hyperoside and orientin were the major flavonoids, with quercetin, luteolin and chrysoeriol detected in trace quantities. Differences (p < 0.05) between aqueous and β-CD assisted CGRE was only observed for aspalathin reporting the highest content of 172.25 mg·g⁻¹ of dry matter for extracts produced at optimal extraction conditions. Positive, strong correlations between TPC and antioxidant assays were observed and exhibited regression coefficient (R²) between 0.929–0.978 at p < 0.001. These results demonstrated the capacity of β-CD in increasing polyphenol content of green rooibos.     

Recent Advancements in Natural Plant Colorants Used for Hair Dye Applications: A Review

There is an on-going demand in recent years for safer and “greener” hair coloring agents with the global consumer awareness of the adverse effects of synthetic hair dyes. The belief in sustainability and health benefits has focused the attention of the scientific community towards natural colorants that serve to replace their synthetic toxic counterparts. This review article encompasses the historical applications of a vast array of natural plant hair dyes and summarizes the possible coloration mechanisms (direct dyeing and mordant dyeing). Current information on phytochemicals (quinones, tannins, flavonoids, indigo, curcuminoids and carotenoids) used for hair dyeing are summarized, including their botanical sources, color chemistry and biological/toxicological activities. A particular focus is given on research into new natural hair dye sources along with eco-friendly, robust and cost-effective technologies for their processing and applications, such as the synthetic biology approach for colorant production, encapsulation techniques for stabilization and the development of inorganic nanocarriers. In addition, innovative in vitro approaches for the toxicological assessments of natural hair dye cosmetics are highlighted.     

Optimization of Wall Material of Freeze-Dried High-Bioactive Microcapsules with Yellow Onion Rejects Using Simplex Centroid Mixture Design Approach Based on Whey Protein Isolate,Pectin, and Sodium Caseinate as Incorporated Variables

For the food sector, onion rejects are an appealing source of value-added byproducts. Bioactive compounds were recovered from yellow onion rejects using a pulse electric field process at 6000 v and 60 pulses. The onion extract was encapsulated with whey protein isolate (WPI), pectin (P), and sodium caseinate (SC) with a mass ratio of 1:5 (extract/wall material, w/w). A Simplex lattice with augmented axial points in the mixture design was applied for the optimization of wall material for the encapsulation of onion reject extract by freeze-drying (FD). The optimal wall materials were 47.6 g/100 g (SC), 10.0 g/100 g (P), and 42.4 g/100 g (WPI), with encapsulation yield (EY) of 85.1%, total phenolic content (TPC) of 48.7 mg gallic acid equivalent/g DW, total flavonoid content (TFC) of 92.0 mg quercetin equivalent/g DW, and DPPH capacity of 76.1%, respectively. The morphological properties of the optimal encapsulate demonstrated spherical particles with a rough surface. At optimal conditions, the minimum inhibitory concentration (MIC) of the extract (mean diameter of inhibition zone: 18.8 mm) was shown as antifungal activity against Aspergillus niger.     

Encapsulation of Vitamin B12 by Complex Coacervation of Whey Protein Concentrate–Pectin; Optimization and Characterization

Vitamin B₁₂ (VB₁₂) is one of the essential vitamins for the body, which is sensitive to light, heat, oxidizing agents, and acidic and alkaline substances. Therefore, the encapsulation of VB₁₂ can be one of the ways to protect it against processing and environmental conditions in food. In this work, the influence of pectin concentration (0.5–1% w/v), whey protein concentrate (WPC) level (4–8% w/v) and pH (3–9) on some properties of VB₁₂-loaded pectin–WPC complex carriers was investigated by response surface methodology (RSM). The findings showed that under optimum conditions (1:6.47, pectin:WPC and pH = 6.6), the encapsulation efficiency (EE), stability, viscosity, particle size and solubility of complex carriers were 80.71%, 85.38%, 39.58 mPa·s, 7.07 µm and 65.86%, respectively. Additionally, the formation of complex coacervate was confirmed by Fourier-transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM). In addition, it was revealed that the most important factor in VB₁₂ encapsulation was pH; at a pH < isoelectric point of WPC (pH = 3), in comparison with higher pH values (6 and 9), a stronger complex was formed between pectin and WPC, which led to an increase in EE, lightness parameter, particle size and water activity, as well as a decrease in the zeta-potential and porosity of complex carriers.     

Combination of Spray-Chilling and Spray-Drying Techniques to Protect Carotenoid-Rich Extracts from Pumpkin (Cucurbita moschata) Byproducts,Aiming at the Production of a Powdered Natural Food Dye

Reducing waste, using byproducts, and natural food additives are important sustainability trends. In this context, the aim of this study was to produce and evaluate a natural food dye, extracted from pumpkin byproducts, powdered and protected by spray-chilling (SC) and a combination of spray-drying and spray-chilling techniques (SDC). The extract was obtained using ethanol as solvent; vegetable fat and gum Arabic were used as carriers. Formulations were prepared with the following core:carrier ratios: SC 20 (20:80), SC 30 (30:70), SC 40 (40:60), SDC 5 (5:95), SDC 10 (10:90), and SDC 15 (15:85). The physicochemical properties of the formed microparticles were characterised, and their storage stability was evaluated over 90 days. The microparticles exhibited colour variation and size increase over time. SDC particles exhibited the highest encapsulation efficiency (95.2–100.8%) and retention of carotenoids in the storage period (60.8–89.7%). Considering the carotenoid content and its stability, the optimal formulation for each process was selected for further analysis. All of the processes and formulations produced spherical particles that were heterogeneous in size. SDC particles exhibited the highest oxidative stability index and the highest carotenoid release in the intestinal phase (32.6%). The use of combined microencapsulation technologies should be considered promising to protect carotenoid compounds.     

Preparation and Optimization of O/W Emulsions Stabilized by Triglycerol Monolaurate for Curcumin Encapsulation

Curcumin is one of the most studied chemo-preventive agents, which may cause suppression, retardation, or inversion of carcinogenesis. But its application is currently limited because of its poor water-solubility and bioaccessibility. A curcumin O/W emulsion was prepared by high-pressure homogenization, using triglyceride monolaurate as an emulsifier and medium chain triglycerides (MCT) as the oil phase. The effects of emulsifiers, emulsifier concentration, oil type, oil-to-water ratio, and homogenization pressure and processing cycles on the physical stability and droplet size distribution of curcumin-encapsulated O/W emulsions were evaluated in this study. The results showed that the mean droplet size of the O/W emulsions remained remarkably stable during 60 days of storage under both light and dark conditions. Curcumin retentions in O/W emulsions after 60 days of storage under light and dark conditions were 97.9% and 81.6%, respectively. In addition, during the simulated gastrointestinal digestion process, the mean droplet size of the O/W emulsions increased from 260 nm to 2743 nm after incubation with simulated gastric fluid (SGF) for 24 h, while the mean droplet size remained unchanged after incubation with simulated intestinal fluid (SIF). The results displayed negligible changes in curcumin content during incubation with simulated gastrointestinal fluids, indicating that effective protection of curcumin was achieved by encapsulation in the O/W emulsion. It is expected that curcumin will acquire high bioaccessibility and bioavailability when the O/W emulsion is to be used in clinical applications.     

Kinetics of Carotenoids Degradation during the Storage of Encapsulated Carrot Waste Extracts

The encapsulates of carrot waste oil extract improved the antioxidant properties of durum wheat pasta. The aim of this research was to study the kinetics of carotenoids degradation in the freeze-dried (FDE) and spray-dried (SDE) encapsulates of carrot waste extract during storage at four different temperatures (+4, +21.3, +30, +37 °C) up to 413 days by HPLC. Carotenoids levels decreased as a function of time and temperature, following zero-order kinetics. At 4 °C carotenes were stable for at least 413 days, but their half-lives decreased with increasing temperatures: 8–12 months at 21 °C; 3–4 months at 30 °C; and 1.5–2 months at 37 °C. The freeze-drying technique was more effective against carotenes degradation. An initial lag-time with no or very limited carotenes degradation was observed: from one week at 37 °C up to 3 months (SDE) or more (FDE) at 21 °C. The activation energies (Ea) varied between 66.6 and 79.5 kJ/mol, and Ea values tended to be higher in FDE than in SDE.