Design of Hierarchical Beads for Efficient Label‐Free Cell Capture

Defined hierarchical materials promise cell analysis and call for application‐driven design in practical use. The further issue is to develop advanced materials and devices for efficient label‐free cell capture with minimum instrumentation. Herein, the design of hierarchical beads is reported for efficient label‐free cell capture. Silica nanoparticles (size of ≈15 nm) are coated onto silica spheres (size of ≈200 nm) to achieve nanoscale surface roughness, and then the rough silica spheres are combined with microbeads (≈150–1000 µm in diameter) to assemble hierarchical structures. These hierarchical beads are built via electrostatic interaction, covalent bonding, and nanoparticle adherence. Further, after functionalization by hyaluronic acid (HA), the hierarchical beads display desirable surface hydrophilicity, biocompatibility, and chemical/structural stability. Due to the controlled surface topology and chemistry, HA‐functionalized hierarchical beads afford high cell capture efficiency up to 98.7% in a facile label‐free manner. This work guides the development of label‐free cell capture techniques and contributes to the construction of smart interfaces in bio‐systems.     

Preparation and Evaluation Of Drug-Containing Chitosan Beads

Abstract

Sulfadiazine beads were prepared by dropping drug-containing solutions of the positively charged polysaccharide, chitosan, into tripolyphosphate (TPP) solutions. The droplets instantaneously formed gelled spheres by ionotropic gelation, entrapping the drug within a three-dimensional network of the ionically linked polymer. To achieve maximum drug content, high payloads, short gelation times, low TPP concentrations, and a low internal to external phase ratio were required. The chitosan beads showed pH-dependent swelling and dissolution behavior. The beads swelled and dissolved in 0.1N HCl, while they stayed intact in simulated intestinal fluid. The release of sulfadiazine in 0.1N HCl decreased with increasing concentration of TPP, but was independent of the TPP concentration in intestinal fluids. The morphology of the beads was investigated by scanning electron microscopy. The porosity of the beads depended on the method of drying.     

Preparation and Evaluation Of Drug-Containing Chitosan Beads

Sulfadiazine beads were prepared by dropping drug-containing solutions of the positively charged polysaccharide, chitosan, into tripolyphosphate (TPP) solutions. The droplets instantaneously formed gelled spheres by ionotropic gelation, entrapping the drug within a three-dimensional network of the ionically linked polymer. To achieve maximum drug content, high payloads, short gelation times, low TPP concentrations, and a low internal to external phase ratio were required. The chitosan beads showed pH-dependent swelling and dissolution behavior. The beads swelled and dissolved in 0.1N HCl, while they stayed intact in simulated intestinal fluid. The release of sulfadiazine in 0.1N HCl decreased with increasing concentration of TPP, but was independent of the TPP concentration in intestinal fluids. The morphology of the beads was investigated by scanning electron microscopy. The porosity of the beads depended on the method of drying.     

Dissolution Controlled Drug Release from Agarose Beads

Abstract

A simple method was used for loading ibuprofen or indomethacin into agarose beads to obtain sustained release. Placebo beads were prepared by a dropwise addition of a hot aqueous agarose solution into a beaker of chilled mineral oil and water. Prior to loading, the aqueous component in the beads was replaced by repeated soakings in ethanol. Loading was accomplished at room temperature using ethanolic drug solutions. Upon drying, the beads shrank to about a third of their original size. The surface morphology of dried placebo and loaded beads was studied using electron microscopy. The release time at 37° C and pH 7.5 increased with drug loading and at 50% loading the release time was 4 hours for indomethacin and 6 hours for ibuprofen. Release of chlorpheniramine from dried and swollen beads was examined to elucidate the release mechanism. From dissolution studies it was concluded that the delay due to swelling is less than 10 minutes, chlorpheniramine release from swollen beads was primarily diffusion controlled, and the release mechanism for indomethacin and ibuprofen has three components: i) swelling of the beads, ii) dissolution of crystallized drug, and iii) diffusion of dissolved drug from the beads.     

玻璃微珠增强硬质聚氨酯泡沫塑料的性能

研究了通过不同偶联剂处理后的不同玻璃微珠对全水发泡硬质聚氨酯泡沫的微观形貌、压缩强度和热稳定性的影响。试验结果表明,玻璃微珠的添加量占聚醚多元醇的6%(质量分数)以下时,玻璃微珠对泡孔形貌影响较小,并且应用偶联剂KH550处理后的玻璃微珠K46对聚氨酯泡沫的增强效果最好。在保持硬质聚氨酯泡沫密度不变的情况下,玻璃微珠K46含量为聚醚多元醇的6%时可提高压缩强度约10%,压缩模量约8%。同时,用玻璃微珠增强后的硬质聚氨酯泡沫热稳定性也有一定的提高。     

Propranolol Hydrochloride Binding in Calcium Alginate Beads

The interaction of propranolol hydrochloride with alginate molecular chains in calcium alginate beads was investigated. The drug was either incorporated into formed calcium alginate gel beads or incorporated simultaneously with the gelation of alginate beads by Ca²⁺. Bed produced by the former method had a higher drug content and lower Ca²⁺ level compared to those prepared by the latter method. The extent of drug binding to the alginate molecules increased with decreasing Ca²⁺ levels in the beads, indicating that propranolol and Ca²⁺ shared common binding sites in the alginate chains, me appearance of the beads and the molphology of the alginate polymer in the beads were affected by the amounts of both propranolol and Ca²⁺ in the beads. Differential scanning calorimetry (DSC) analyses showed that the formation of the calcium alginate gel structure was impeded in the presence of propranolol molecules.     

Propranolol Hydrochloride Binding in Calcium Alginate Beads

Abstract

The interaction of propranolol hydrochloride with alginate molecular chains in calcium alginate beads was investigated. The drug was either incorporated into formed calcium alginate gel beads or incorporated simultaneously with the gelation of alginate beads by Ca²⁺. Bed produced by the former method had a higher drug content and lower Ca²⁺ level compared to those prepared by the latter method. The extent of drug binding to the alginate molecules increased with decreasing Ca²⁺ levels in the beads, indicating that propranolol and Ca²⁺ shared common binding sites in the alginate chains, me appearance of the beads and the molphology of the alginate polymer in the beads were affected by the amounts of both propranolol and Ca²⁺ in the beads. Differential scanning calorimetry (DSC) analyses showed that the formation of the calcium alginate gel structure was impeded in the presence of propranolol molecules.     

镀银磁性PMMA微球的制备

采用化学镀法制得了表面包覆银层的导电磁性聚甲基丙烯酸甲酯(PMMA)微球。对粗糙度不同的微球进行镀银,研究了银在微球上的沉积机理。表面改性使磁性PMMA微球功能化,具有和银强烈结合的能力,从而得到包覆均匀的导电磁性微球。研究了硝酸银和磁性微球的含量对包覆效果及导电性能的影响,并通过SEM和EDS对镀银磁性微球的表面形貌及组成进行了分析。     

Formulation and Compaction of Nonfracturing Deformable Coated Beads

Abstract

There has been considerable interest in making tablets from spheronized bead rather than through encapsulation. It is obvious that the forces present during compaction may break a coating intended to control drug release. This effect may be moderated by cushioning agents incorporated into the bead formulation or situation between the beads. Our work describes the latter method.     

Formulation and Compaction of Nonfracturing Deformable Coated Beads

There has been considerable interest in making tablets from spheronized bead rather than through encapsulation. It is obvious that the forces present during compaction may break a coating intended to control drug release. This effect may be moderated by cushioning agents incorporated into the bead formulation or situation between the beads. Our work describes the latter method.     

Preparation and Evaluation of Sustained Release Ibuprofen Beads

Sustained release beads of ibuprofen were prepared by a capillary method using cellulose acetate phthalate, surfactants (Tween 80 and Span 80), and polymers (K 100 M Methocel and K 100 LV Methocel). These beads were formulated into capsule and tablet dosage forms. The beads did not disintegrate in simulated gastric fluid; however, they disintegrated in simulated intestinal fluid. The dissolution profiles of ibuprofen beads and dosage forms of beads (tablets and capsules) were conducted in phosphate buffer (pH 7.2) at 37°C. The beads containing Span 80 and K 100 M Methocel resulted in prolonged drug release. The preparation containing Span 80 and equal quantities of both the polymers (K 100 M Methocel and K 100 LV Methocel), also showed good sustained release properties. The formulations prepared with Tween 80 and K 100 LV Methocel released over 90% of the drug in 2 hours indicating no sustained release properties. The beads in tablet dosage form yielded slower dissolution profiles compared to the beads in capsule form which, in turn, had slower release profiles compared to the beads alone. Release of ibuprofen was much slower from tablets after one year of storage compared to tablets immediately after their manufacture.     

Preparation and Evaluation of Sustained Release Ibuprofen Beads

Sustained release beads of ibuprofen were prepared by a capillary method using cellulose acetate phthalate, surfactants (Tween 80 and Span 80), and polymers (K 100 M Methocel and K 100 LV Methocel). These beads were formulated into capsule and tablet dosage forms. The beads did not disintegrate in simulated gastric fluid; however, they disintegrated in simulated intestinal fluid. The dissolution profiles of ibuprofen beads and dosage forms of beads (tablets and capsules) were conducted in phosphate buffer (pH 7.2) at 37°C. The beads containing Span 80 and K 100 M Methocel resulted in prolonged drug release. The preparation containing Span 80 and equal quantities of both the polymers (K 100 M Methocel and K 100 LV Methocel), also showed good sustained release properties. The formulations prepared with Tween 80 and K 100 LV Methocel released over 90% of the drug in 2 hours indicating no sustained release properties. The beads in tablet dosage form yielded slower dissolution profiles compared to the beads in capsule form which, in turn, had slower release profiles compared to the beads alone. Release of ibuprofen was much slower from tablets after one year of storage compared to tablets immediately after their manufacture.     

Hierarchical wave-front sensing

We present a new wave-front sensing technique for adaptive optics based on use of several wave-front sensors dedicated to the sensing of a different range of spatial frequencies. We call it a hierarchical wave-front sensor. We present the concept of a hierarchical wave-front sensor and apply it to the Shack-Hartmann sensor. We show the gain that is expected with two Shack-Hartmann sensors. We obtain a gain that increases with the size of the largest sensor, and we detail the application of hierarchical wave-front sensing to extreme adaptive optics and extremely large telescopes.