Tissue Regeneration in Infected Wounds of Albino Rats Using Ciprofloxacin-Loaded Gelatin Microspheres Incorporated Collagen Scaffold: A Histological Approach with H&E Staining

A wound care system consisting of ciprofloxacin-loaded gelatin microspheres impregnated in a macroporous collagen scaffold was created to effectively control wound infection and regenerate soft tissue at the wound site.Histological and biochemical alterations were observed in infected wounds treated with these scaffolds in Albino Wistar rats.Furthermore,the study examined the immediate and prolonged release of ciprofloxacin from the scaffolds,as well as their function in eliminating bacterial infections and expediting the process of skin healing and regeneration.The developed technique was followed in the streamlined process of creating these collagen scaffolds.Compared to untreated wounds,the group receiving scaffold treatment experienced a faster rate of wound closure.It was noted that the rate of infections was considerably reduced and that full soft tissue regeneration occurred within 12 days.The development of well-deposited collagen bundles in the treated groups was demonstrated by H&E staining,which verified the flawless regeneration of the dermis and epidermis.The antimicrobial agent-loaded gelatin microspheres impregnated into the porous collagen scaffold demonstrated remarkable soft tissue regeneration and efficient infection control at the wound site.

Structure-Property Relationships and Models of Controlled Drug Delivery of Biodegradable Poly (D, L-lactic acid) Microspheres

An oil-in-water (O/W) solvent evaporation method was used to prepare biodegradable microspheresbased on poly(D,L-lactic acid) (PLA). Nifedipine, a hydrophobic drug, was chosen as a model molecule in the studyof drug entrapment and release. Effect of preparation conditions on the size, morphology, drug loading, and releaseprofiles of micropheres was investigated. Based on in vitro release experimental findings, a diffusion/dissolutionmodel was presented for quantitative description of the resulting release behaviors and drug release kinetics fromPLA microspheres analyzed. The mathematical models were used to predict the effect of microstructure on theresulting drug release. It provided an approach to determine the suitable structure parameters for microspheres toachieve desired drug release behaviors.

Preparation and performance of fluorescent polyacrylamide microspheres as a profile control and tracer agent

Polyacrylamide microspheres have been suc- cessfully used to reduce water production in reservoirs, but it is impossible to distinguish polyacrylamide microspheres from polyacrylamide that is used to enhance oil recovery and is already present in production fluids. In order to detect polyacrylamide microspheres in the reservoir pro- duced fluid, fluorescent polyacrylamide microspheres P（AM-BA-AMCO）, which fluoresce under ultraviolet irradiation, were synthesized via an inverse suspension polymerization. In order to keep the particle size distribu- tion in a narrow range, the synthesis conditions of the polymerization were studied, including the stirring speed and the concentrations of initiator, NaaCO3, and dispersant. The bonding characteristics of microspheres were deter- mined by Fourier transform infrared spectroscopy. The surface morphology of these microspheres was observed under ultraviolet irradiation with an inverse fluorescence microscope. A laboratory evaluation test showed that the fluorescent polymer microspheres had good water swelling capability, thus they had the ability to plug and migrate in a sand pack. The plugging rate was 99.8 % and the residual resistance coefficient was 800 after microsphere treatment in the sand pack. Furthermore, the fluorescent microspheres and their fragments were accurately detected under ultra- violet irradiation in the produced fluid, even though theyhad experienced extrusion and deformation in the sand pack.

LIVING/CONTROLLED GRAFTING FROM POLYMER MICROSPHERES

A review is given of grafting-from methods using living polymerizations, with emphasis on grafting from polymermicrospheres using ATRP.

Preparation and Characterization of IPN Microspheres for Controlled Delivery of Naproxen

Interpenetrating network (IPN) microspheres of sodium alginate (NaAlg) and poly (vinyl alcohol) (PVA) were prepared and crosslinked with glutaraldehyde (GA) by using the water in oil (W/O) emulsification method to deliver naproxen sodium (NS). NS was successfully encapsulated into IPN microspheres in different ratios of NaAlg and PVA (w/w), drug loading percentage (w/w) and crosslinking time. Crosslink density of the matrices was affected by the time of crosslinker. The prepared microspheres were characterized by Fourier transform infrared spectroscopy (FTIR). Pictures of selected microspheres were determined using optic microscope. Results confirmed the dispersion of NS in the microspheres. Release of NS from the microspheres was investigated in pH 1.2, 6.8 and 7.4 media for two hours respectively. The highest NS release was obtained as 92% (w/w) by using UV spectroscopy. Equilibrium swelling was performed in pH 7.4 buffer solution at 37℃.

Study of targeted and controlled release of 5-fluorouracil-loaded PLA nanoparticles and microspheres on treatment of gastric tumor

The aim of this paper was to evaluate controlled release behavior and the therapeutic efficacy of 5-FU-loaded Poly(lactic acid) (PLA)microspheres to human gastric cancer xenograft, and the targeting effect of VEGF/5-FU loaded PLA nanoparticles. 5-FU-loaded PLA microspheres were prepared by an emulsion evaporation method, and were characterized by scanning electron microscopy (SEM). 5-FU loaded PLA nanoparticles were characterized by (TEM), and particle size analyzer determined the distribution of nanoparticles size. The release performances of 5-FU microspheres in vitro were studied in PH 7.4 phosphate buffered saline. The therapeutic efficacy of 5-FU-loaded PLA microspheres in vivo were studied using MGC-803 (human stomach cancer) xenograft. 32 nude mice were divided into four groups (n =8), 5-FU loaded PLA microspheres were injected at tumor site. VEGF121 monoclonal antibody was connected with 5-FU loaded PLA nanoparticles through carbodimide. The targeted effect of VEGF 5-FU loaded nanoparticles in vivo were observed by single photon emission computed tomography (SPECT) after tail vein injection at 1 h and 2 h. SEM observation showed that microspheres were spherical, and the diameters of two kinds of microspheres were 1 μm and 5 μm respectively. The mean diameter of nanoparticles was 191.0 nm, and the index of polydispersity was 0.202. The drug was released following biphasic kinetics, initial burst and the following steady phase. 1 μm and 5 μm 5-FU-loaded microspheres both resulted in increased life span (1 μm microspheres median survival time=40.63 days, 5 μm microspheres median survival time=62.25 days), against 5-FU pure drug (median survival time=14.5 days). These results strongly suggest that 5-FU-loaded PLA microspheres increase life span of nude mice bearing MGC-803 tumors. After injection for 2 h, almost all the VEGF/5-FU loaded PLA nanoparticles could centralize at the human gastric cancer xenograft sites. That demonstrated VEGF monoclonal antibody remain its bioactivity after connection with nanoparticles, VEGF/5-FU loaded PLA nanoparticles had very exact targeting function for gastric tumor xenograft.

Crystal phase control and ignition properties of HNS/CL-20 composite microspheres prepared by microfluidics combined with emulsification techniques

Improved controllability and energy density of ignition agents are of great significance for the devel-opment of energetic composite materials.In this study,droplet microfluidics and emulsification tech-niques were combined to prepare HNS/CL-20 composite microspheres with polyglycidyl azide polymer(GAP)as the binder.The influence of binder content on the morphology of microspheres was investi-gated,and the microspheres were characterized and tested for particle size,crystal structure,thermal decomposition,dispersibility,mechanical sensitivity,combustion behavior and detonation performance.The results showed that microspheres prepared with a binder content of 3%had higher sphericity and particle size uniformity.The microspheres retained the crystal structure of both HNS and CL-20(ε-type).Compared with raw HNS,the microspheres had higher apparent activation energy,better safety per-formance,and good dispersibility.The ignition experiments and detonation performance tests show that HNS/CL-20 composite microspheres have excellent ignition performance,obvious combustion flame,and significant energy release effects,which are expected to achieve high energy and high-speed response of the igniter,thus improving the ignition reliability in special environments or systems.

Preparation, Characterization and Drug-Release Behaviors of Crosslinked Chitosan/Attapulgite Hybrid Microspheres by a Facile Spray-Drying Technique

A series of chitosan/attapulgite (CTS/APT) hybrid microspheres were prepared by a facile spray-drying technique. The developed hybrid microspheres were characterized by Fourier transform infrared spectra (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and the zeta potential. The encapsulation efficiency and in vitro controlled release properties of the microspheres for drug were evaluated using diclofenac sodium (DS) as a model drug. Results indicated that the introduction of APT into crosslinked CTS microspheres can achieve narrow size distribution and make them more uniform. The isoelectric point of the microspheres increased from 8.14 to 9.18 with increasing the content of APT to 10 wt.%. DS loaded in hybrid microspheres is hardly released in simulated gastric fluid, but quickly released in simulated intestinal fluid. The electrostatic interaction between hybrid microspheres and DS can improve the encapsulation efficiency and controlled release behavior of CTS/APT microspheres, and the release mechanism fits Fickian diffusion.

Preparation of PLLA/bpV(pic) Microspheres and Their Effect on Nerve Cells

In this study, we prepared PLLA/bpV（pic） microspheres, a bpV（pic） controlled release system and examined their ability to protect nerve cells and promote axonal growth. PLLA microspheres were prepared by employing the o/w single emulsification-evaporation technique. Neural stem cells and dorsal root ganglia were divided into 3 groups in terms of the treatment they received： a routine medium group（cultured in DMEM）, a PLLA microsphere group（DMEM containing PLLA microspheres alone） and a PLLA/bpV（pic） group [DMEM containing PLLA/bpV（pic） microspheres]. The effects of PLLA/bpV（pic） microspheres were evaluated by the live-dead test and measurement of axonal length. Our results showed that PLLA/bpV（pic） granulation rate was（88.2±5.6）%; particle size was（16.8±3.1）%, drug loading was（4.05±0.3）%; encapsulation efficiency was（48.5±1.8）%. The release time lasted for 30 days. In PLLA/bpV（pic） microsphere group, the cell survival rate was（95.2 ±4.77）%, and the length of dorsal root ganglion（DRG） was 718±95 μm, which were all significantly greater than those in ordinary routine medium group and PLLA microsphere group. This preliminary test results showed the PLLA/bpV（pic） microspheres were successfully prepared and they could promote the survival and growth of neural cells in DRG.

油田监测用密度可控同位素示踪微球的制备及应用

制备了用于油田监测的同位素示踪微球,分析了微球的形貌、抗压强度、热性能、耐溶剂性和加工性能,揭示了微球与同位素产率及加工性能的构效关系,提出了示踪微球密度计算方法。结果表明:示踪微球表面形貌主要为致密和松散两种,抗压强度的影响因素主要为黏合剂种类与加料方式;采用不同黏合剂制备的微球耐溶剂性差别较大,采用酚醛胺和聚酰胺制备的示踪微球抗压强度较高,耐热性较好;采用炭粉为原料获得的同位素产率较高;微球密度的调控可以通过一个经验系数来计算。

脲醛树脂前驱体碳微球形貌调控及电化学性能研究

为了探究原料配比对脲醛树脂形貌及碳微球电化学性能的影响,通过改变尿素、甲醛与甲酸的物质的量比,制备了三种不同微纳结构的脲醛树脂微球,再在氮气保护下800℃裂解,获得了相应的碳微球。采用上述脲醛树脂前驱体制备的花状碳纳米微球(NUFC-3)作为电极材料,在三电极体系中开展电化学性能研究。结果表明,在1 A/g的电流密度下,比电容(C_(s))为189 F/g;在20 A/g的电流密度下,C_(s)为145 F/g,其保留率为76.7%。该脲醛树脂为前驱体的碳微球具有制备方法简单、成本低廉及电化学性能优异等优点,有望在电化学储能领域获得应用。

水基四元超分子微球功能评价及深部调剖适应性

为解决海上高含水油藏聚合物微球耐温、耐盐和抗剪切性能差导致应用效果变差的问题,采用分散聚合方法制备了一种水基四元超分子微球,并进行了性能表征及深部调驱能力评价。结果表明,该超分子微球在温度90℃、矿化度7×10^(4)mg/L、剪切速率3 000 s^(-1)条件下具有良好的稳定性,表现出良好的耐温、耐盐和抗剪切性能;在100~3 000 mD的岩心中具有良好的注入性与封堵性;对于高含水非均质岩心可实现采收率增幅达16.68%~20.56%,具有良好的应用潜力。

耐高温水基微球调驱剂性能评价

评价了一种耐高温水基微球调驱剂性能。实验结果表明:不同浓度耐温水基微球调驱剂注入不同渗透率岩心的阻力系数均小于等于5,注入性好;浓度为4 000 mg/L的耐温水基微球调驱剂在岩心中的有效封堵渗透率范围最大,封堵率最高超过90%;该水基微球调驱剂在150℃下有效封堵时间45 d左右,耐温性良好;该耐温水基微球调驱剂可提高渤海油田非均质储层原油采收率15.41%~17.92%。

磁性微球机器人在模拟血液中的运动控制

微纳机器人因其尺寸小、操控精度高、易到达小腔道等优点,可精确、高效地递送药物,是未来精准医学的新方向。本文以明胶为基材,构建了磁性微球机器人系统,它兼具明胶对环境无毒、无污染、生物可降解的优点,以及磁场对生物组织无害、不与物质直接接触而实现控制等优点。通过优化制备条件如明胶浓度、搅拌速度和乳化剂的浓度及乳化时间,制备出稳定、均匀的明胶磁性微球。研究了粒径、磁场强度、频率及液体粘度对粒子运动的影响,进一步探讨了粒子在不同浓度的模拟血液中的运动控制。今后,可以结合机器视觉、自动识别导航等从而真正体现微纳技术的优势,有望获得广阔的医学应用前景。

纳米聚合物微球调驱全过程探索研究

为了研究纳米聚合物微球深部调驱机理、生产现场应用效果以及对后期原油破乳脱水的影响,应用光学显微镜、扫描电镜对纳米聚合物微球粒径变化规律进行观察,并分析内在原因,采用热沉降化学法等手段研究微球乳液是否对原油破乳脱水产生影响,同时,结合生产现场试验应用效果,对纳米聚合物微球调驱进行了全过程探索研究。结果表明:小粒径微球更易进入油层深部滞留,微球本身膨胀变大进行封堵,增大油层比表面积,降低油层渗透率,其调驱适应性小粒径聚合物微球更占优势,现场应用效果明显,有效缓解了含水率上升的矛盾,取得了良好的控水效果。经室内实验证明,采出液中的微球乳液对原油破乳脱水基本不产生影响,甚至有一定的正向作用。

玻璃微珠填充硅树脂可磨耗层的制备工艺及其在航空发动机静子组合件上的应用

树脂基可磨耗层是航空发动机静子组合件的重要组成部件,利用其可磨耗性可保护转动件与静子组合件,并通过减小转动件与静子组合件之间的间隙优化航空发动机性能。采用加成型硅树脂为基体,研究不同粒径与堆积密度的实心/空心玻璃微珠对复合磨耗层加工性能的影响规律;采用专用磨耗试验机模拟高速叶片磨耗工况,研究不同种类与含量玻璃微珠对硅树脂复合材料磨耗性能的影响规律。结果表明:H型(粒径分布20~80 um)空心玻璃微珠填充硅树脂复合材料具有优异的表面质量、流淌性与综合性能。通过玻璃微珠填充填料优选与含量调控,结合工装设计以及灌注工艺参数调控,形成玻璃微珠填充硅树脂可磨耗层的可控制备工艺,并在航空发动机静子组合件上得到应用与验证。

原位制备ZIF-8/纤维素微球及其控制释放5-氟尿嘧啶的研究

在纤维素微球(CM)上设计了沸石型咪唑骨架材料8/纤维素复合微球(ZIF-8@CM)作为5-氟尿嘧啶(5-FU)的载体并对5-FU进行控制释放。以CM、硝酸锌和2-甲基咪唑为原料,采用原位法制备了ZIF-8@CM。通过氢键、静电相互作用和π-π堆积作用将5-FU加载到ZIF-8@CM上。利用扫描电子显微术、能量色散X射线分析法、傅里叶变换红外光谱法、X射线衍射、X射线光电子能谱法和热重分析对样品进行表征,结果表明成功制备了ZIF-8@CM,并在ZIF-8@CM上成功加载了5-FU。ZIF-8@CM对5-FU的负载量可达74.10 mg·g^(-1),远高于CM(2.84 mg·g^(-1))。此外,ZIF-8@CM-5-FU可在pH=5.0的磷酸缓冲溶液(PBS)环境下持续释放5-FU 600 min,释放量达到63.4%,但在pH=7.4的PBS环境下仅释放37.6%。5-FU的释放遵循一级动力学和Fickian扩散机制。在细胞实验中已证实ZIF-8@CM具有良好的生物相容性和极低的细胞毒性,是5-FU安全释放的合适载体。本研究为设计一种5-FU的新型载体提供了思路。

Construction of controllable size silver nanoparticles immobilized on nanofibers of chitin microspheres via green pathway

In the present work, nanofibrous chitin microsphere （NCM） was prepared via sol-gel transition from a chitin solution dissolved in a NaOH/urea aqueous system at low temperatures. Ag nanoparticles （AgNPs） were synthesized via an in situ reduction of silver nitrate using trisodium citrate dehydrate and were immobilized on chitin nanofibers to obtain composite microspheres that consist of nanofibers and AgNPs （NCM-Ag）. The size of AgNPs could be controlled in the range of 10 to 70 nm, depending on the concentration of AgNO3. X-ray photoelectron spectroscopy （XPS） and Fourier transform infrared （FT-IR） analyses showed that the chitin nanofibers have a strong affinity toward AgNPs, resulting from the interaction between the acetamino group of chitin and the AgNPs. The NCM-Ag exhibited a perfect nanoporous structure and high surface area, as well as high stability in organic solvents. Moreover, in the catalytic epoxidation of olefin （particularly, the conversion of styrene to styrene epoxide）, NCM-Ag exhibited an excellent selectivity of up to 90%. Converting chitin powder into chitin microspheres using an environmentally friendly technique is a green process, which is beneficial for the large-scale synthesis of industrial products. More importantly, this work provides a green synthetic pathway for the construction of size-controlled noble metal nanoparticles immobilized on nanofiber support, which have a wide range of potential applications.

Facile and Controllable Assembly of Multiwalled Carbon Nanotubes on Polystyrene Microspheres

Herein a facile and controllable heterocoagulation between polystyrene （PS） microspheres and multiwalled carbon nanotubes （MWCNTs） is introduced based on colloid thermodynamics. The MWCNTs play the role of steric stabilizer for stabilizing the metastable PS microspheres and thus immobilize spontaneously on the surface of PS microspheres. The synthesized MWCNTs-coated PS composite particles have been extensively characterized by scanning electron microscopy, transmission electron microscopy, thermogravimetry and Raman spectroscopy. The results indicate that the structure and morphology of the resultant MWCNTs-coated PS composite particles are significantly affected by the weight ratio of PS and MWNCTs and the amount of poly（vinylpyrrolidone） that is injected into PS dispersion before they are mixed with MWCNTs. Therefore, these composite particles have the potential to produce MWCNTs-based composite materials with controllable mass loading and dispersity of MWCNTs.