Gradient-Field Sorting of Microparticles

The method of spatial sorting of different types of microparticles in a liquid with the aid of a gradient laser field has been proposed and implemented. The method is based on linear scanning of the interference fringes of the field imposed on a suspension. It is shown theoretically that at given parameters of the particles and field it is possible to select such a rate of scanning of interference fringes at which only the particles of one species will be captured and carried in the wake of the field, while others are left in place. The efficiency of the proposed method of selection of particles is confirmed experimentally with an example of a water suspension of polymeric small balls of diameter 5.8 and 10 m illuminated by interference fringes of He–Ne laser radiation ( = 632.8 nm). The implemented method of control of microparticles can find application in physics, biology, medicine, microtechnology, and also in a number of other fields.     

Microwire array for giant magneto-impedance detection of magnetic particles for biosensor prototype

A new giant magneto-impedance (GMI) biosensor prototype based on a glass-coated microwires array is reported. The optimal measurement conditions and the influence of a liquid suspension of commercially available polymer-based magnetic microparticles on the magneto-impedance (MI) response of the array were studied. The relative change in MI response enlarges as the number of the active microwires increases. The highest variation of 35% was found for 10 active microwires, for a current intensity of 10 mA. Some possible applications of the biosensor prototype are outlined.     

pH‐responsive starch microparticles for a tumor‐targeting implant

Much progress has been made toward stimuli‐responsive polysaccharide‐based selective tumor therapy not only because polysaccharides have nontoxic biodegradability and biocompatibility but also because their stimuli‐sensitive characteristics enable the proper transport of payloads into tumors. Here, we attempted to deliver an antitumor drug, doxorubicin (DOX), using starch‐based microparticles coupled with pH‐responsive 3‐(diethylamino)propylamine. The microparticles of starch conjugated with 3‐(diethylamino)propylamine (SDEAP) allowed for the change in hydrophobicity of SDEAPs in a pH‐dependent manner. The results revealed that SDEAPs effectively carried and released DOX and selectively killed tumor cells under acidic condition. Overall, this study suggests that DOX‐loaded SDEAPs can be further explored as a strategy for applications to acidic tumor‐targeting implants owing to the drug‐deliver efficiency and tumor selectivity.     

Sol-Gel Route to Direct Formation of Silica Aerogel Microparticles Using Supercritical Solvents

A simple and versatile method to obtain silica aerogel particles based on the hydrolysis and subsequent condensation of silicon alkoxides in supercritical fluids is proposed. This microparticle production route reduces the number of steps of traditional microparticle sol-gel processing.A case example is explained in more detail. Spherical and fiber silica morphologies were obtained by a one step method using a sol-gel process with supercritical acetone as a solvent. Particle size was controlled by varying the relative amounts of alkoxysilane, water and acetone. The resulting materials are influenced by a large number of experimental parameters; it has been observed that a quite relevant one is the supercritical fluid venting rate. The morphology of the particles was characterized by electron microscopy (SEM and TEM) and Atomic Force Microscopy (AFM). Alternatively, a low temperature synthesis can be performed by using supercritical carbon dioxide as solvent and formic acid as condensation agent.     

分子印刷技术铂微粒修饰电极及甲醇的电催化氧化

利用分子印刷技术(Molecular Imprinting Technology，MIT)，将铂微粒沉积到谷胱甘肽自组装膜的针孔上，并用循环伏安法研究了甲醇在该电极上的电催化氧化行为。实验结果表明，该电极对甲醇电化学氧化呈现出较高的催化活性，活性高低与载铂量、溶液pH值及电极表面铂微粒所处的微环境有关。     

A Green Approach to Producing Polymer Microparticles for Local Sustained Release of Flavopiridol

Poly(lactic-co-glycolic acid)(PLGA) microparticles represent an important class of materials used for drug delivery. Current synthesis frequently uses conventional emulsion, where dichloromethane(DCM) is used as the organic phase solvent. Due to the health and environmental toxicity of DCM and its slow degradation, this work replaces DCM with a greener solvent, dimethyl carbonate(DMC). To attain narrow distribution of PLGA particle size, microfluidic flow focusing was chosen over conventional emulsion. This new approach successfully produced PLGA microparticles encapsulated with flavopiridol, a kinase inhibitor. These particles exhibit sustained release profile more desirable than the conventional counterparts. The cytotoxicity and activity tests have demonstrated high biocompatibility and efficacy of these PLGA particles. The high sustainability is also evaluated using simple E-Factor(sEF) and complete E-Factor(cEF). The lower health and environmental toxicities of DMC than DCM are evidenced by approximately one order of magnitude higher in lethal dose, i. e., 50%(LD₅₀) values in rat, 5-fold faster degradation rate, and 30% higher GlaxoSmithKline(GSK) combined greenness value. The approach reported in this work shall provide a new and green means for drug delivery in general. The products enable local sustained delivery of flavopiridol for prevention of post-traumatic osteoarthritis, and anti-cancer therapy.     

Acoustic characterization of a new trisacryl contrast agent. Part II: Flow phantom study and in vivo quantification

The biocompatible trisacryl particles (TMP) are made of a cross-linked acrylic copolymer. Their inherent acoustic properties, studied for a contrast agent application, have been previously demonstrated in a in vitro Couette device. To measure their acoustic behaviour under circulating blood conditions, the TMP backscatter enhancement was further evaluated on a home-made flow phantom at different TMP doses (0.12-15.6 mg/ml) suspended in aqueous and blood media, and in nude mice (aorta and B16 grafted melanoma). Integrated backscatter (IB) was measured by spectral analysis of the Doppler signals recorded from an ultrasound system (Aplio^®) combined with a 12-MHz probe. Doppler phantom experiments revealed a maximal IB of 17 ± 0.88 dB and 7.5 ± 0.7 dB in aqueous and blood media, respectively. IB measured on mice aorta, in pulsed Doppler mode, confirmed a constant maximal value of 7.29 ± 1.72 dB over the first minutes after injection of a 7.8 mg/ml TMP suspension. Following the injection, a 60% enhancement of intratumoral vascularization detection was observed in power Doppler mode. A preliminary histological study revealed inert presence of some TMP in lungs 8 and 16 days after injection.Doppler phantom experiments on whole blood allowed to anticipate the in vivo acoustic behaviour. Both protocols demonstrated TMP effectiveness in significantly increasing Doppler signal intensity and intratumoral vascularization detection. However, it was also shown that blood conditions seemed to shadow the TMP contrast effect, as compared to in vitro observations. These results encourage further investigations on the specific TMP targeting and on their bio-distribution in the different tissues.     

Micronization of the officinal component baicalin by SEDS‐PA process

Application of micronizing technologies in processing Chinese herbal medicines is very important to improve the forms of prepared Chinese herbal medicines and promote their therapeutic efficacy. Baicalin, a major active component of the typical Chinese herb medicine Scullateria baicallensis Georgi, was micronized using the Solution Enhanced Dispersion by Supercritical fluids though Prefilming Atomization (SEDS‐PA) process with the aim of evaluating the efficiency of applying supercritical fluid precipitation technologies in Chinese herb medicine. This study has shown that acicula or rod‐like baicalin crystals with Particle Size (PS) of about 20×100 μm were successfully micronized by the SEDS‐PA process to long rod‐like, twisted fiber‐like or fibrous net‐like microparticles with PS of 0.1‐2.2 μm in width within the range of experiments performed. It was found that a substantial reduction of baicalin microparticles' sizes could lead to a marked increase of adhesions among them and subsequent microparticles agglomeration. With the increase of supercritical CO₂ flow rate and the decrease of solution concentration and solution flow rate, smaller and much more agglomerated microparticles were obtained. Increasing pressure led to formation of smaller microparticles. A larger tendency of particles agglomeration was produced at a higher temperature. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

电位溶出法测定铅和镉

重金属铅和镉元素在环境中普遍存在并可长期蓄积,是不可降解的环境污染物,常危害人体健康.建立快速准确的测定方法具有实际意义[1].     

磁性微粒子化学发光免疫分析法测定人血清中雌三醇

利用化学发光免疫分析(chemiluminescence immunoassay, CLIA)高灵敏度和高特异性的特点, 将磁性微粒子应用于化学发光免疫分析中, 用两种不同的方法对人体血清内的雌三醇(E3)含量进行了测定. 磁性微粒子分别作为固相一抗包被材料和二抗分离剂参与反应. 两种方法检测雌三醇浓度的线形范围均为0.6～60 ng/mL. 其中, 固相一抗法的批内变异及批间变异系数分别小于11%和15%, 回收率为90%～116%, 健全性系数为0.9987. 二抗分离法的批内变异及批间变异系数分别小于8%和10%, 回收率为88%～118%, 健全性系数为0.9974. 两种方法分别与经典板式化学发光法对比, 检测人血清样本, 结果相关性较好, 且磁性微粒子法更为省时、简便, 适于推广应用.