Biomedical subjects

Bailing Liu

Publications and source records attributed to Bailing Liu.

7 recordsLinked to original sources

PubMed2006

Behaviors of enzyme immobilization onto functional microspheres.

Micron-grade monodisperse PMMA microspheres, whose surfaces were modified with functional groups by co-polymerisation using functional monomer, were prepared via dispersion polymerisation. Characterized by their large specific surface area, high adsorption ability, favourable biocompatibility, these monodisperse micron-sized PMMA microspheres were employed as the supporting material in the enzyme immobilization in present work. The influential factors on the activity of immobilized enzyme including pH, temperature, time etc were preliminarily investigated. The results concluded from the experiments indicated that the immobilization procedure could promote the resistance of enzyme against temperature, pH shift and some other tough reaction conditions meanwhile prolong the enzymatic lifetime for storage.

Enzymes, Immobilized↗

PubMed2006

Properties of immobilized pepsin on Modified PMMA microspheres.

In this work we use micro-size poly(methyl methacrylate)/acrylaldehyde microspheres as a support for pepsin immobilization. The aldehyde groups on the microspheres offer a very simple, mild and firm combination for enzyme immobilization. The amount of enzyme we can bind to this support reaches 82 mg/g, which is much higher than for other supports (mostly less than 10 mg/g). Compared to free enzyme, the Km of immobilized enzyme is increased, whereas the Vmax is decreased. Further, the Vmax/Km value for immobilized pepsin is about 50% of the value for free enzyme. This is better than values reported previously, generally lower than 35%. The optimum temperature shifts from 43 degrees C for free pepsin to 47 degrees C. However, the optimum pH does not change between free and immobilized enzyme. This improved resistance of the immobilized enzyme towards changes in temperature and pH also shows that the aldehyde modified poly(methyl methacrylate)/acrylaldehyde microspheres can be a valuable support for pepsin immobilization.

Coated Materials, Biocompatible↗

PubMed2005

Core/shell particles containing 3-(methacryloxypropyl)-trimethoxysilane in the shell: synthesis, characterization, and application.

In comparison to the corresponding single-component counterparts, core/shell particles are widely used due to their better physical and chemical properties. The surface properties of core/shell particles evidently play an important role in the process of application. It is easy to deduce that surface properties mostly depend on the properties of the component in the shell. Therefore, desirable materials of shell are very significant for the study of composite materials, especially in core/shell field. It is well known that polysiloxane has excellent properties, such as the water repellency, high flexibility, low surface energy, and biocompatibility. Its application, however, is limited due to poor cohesiveness and poor film-forming properties. Recently, much endeavor has been made to overcome such flaws. It is found that polyacrylate is commonly considered for its good cohesiveness and excellent film-forming property. The combination of polysiloxane and polyacrylate has been shown to be important in the composite material field, especially as core/shell particles. Unfortunately, their hydrophobicity is considerably different and thus, the core/shell particles consisting of polyacrylate (PA)/polysiloxane (PSi) are hard to prepare by general seeded emulsion polymerization, and are also scarcely available in the literature. In this study, the new core/shell PA/PSi particles with poly(butyl methacrylate) (PA) as the core and poly(3-(methacryloxypropyl)-trimethoxysilane) (PSi) as the shell were prepared by dispersion polymerization under the kinetically controlled conditions. The characterization of the particles by TEM, DSC, particle size analyzer as well as static contact angle confirmed the formation of core/shell structure. The application of core/shell (PA/PSi) particles also has been considered and discussed here.TEM micrographs of core/shell (PA/PSi) particles.

Capsules↗

PubMed2005

Application of scintillation proximity assay in drug discovery.

Scintillation proximity assay (SPA), characterized by its speed, sensitivity, reliability, and the fact that no separation step is required, has become an important technique in high-throughput screening (HTS) for new drugs, and for investigating their biological interactions. The SPA technique now plays a key role in HTS, in that it can be used in many assay formats including radioimmunoassays (RIAs), ligand-receptor binding assays, and enzyme assays. The SPA-based enzyme assay is usually designed in three formats corresponding to different enzymes: signal removal format for hydrolytic enzymes, signal addition format for polymerase and transferase enzymes, and product capture format for antibodies, DNA probes, receptors or other specific binding proteins. The use of SPA in RIAs has been facilitated by new carriers, such as membranes that can be configured in various shapes and sizes, allowing the assay to be performed on samples from many sources including tissue, serum, plasma or cells. This review presents the principles of SPA, discusses supporting materials and quenching effects, as well as detailed examples of the latest advances.

Animals↗

PubMed2004

Sustained release of BSA from a novel drug delivery matrix -- bullfrog skin collagen film.

A novel drug delivery system, bullfrog skin collagen film, was employed to release bovine serum albumin (BSA). The biophysical properties of bullfrog skin collagen film used were evaluated by thermal denaturation temperature and percentage water loss. The film obtained exhibited good stability and can be taken as a good candidate for drug delivery matrix. Compared with conventional collagen from molecular weight and amino acid composition, bullfrog skin collagen showed significant differences. For safety considerations, bullfrog skin collagen has great advantages. The release kinetics of BSA from bullfrog skin collagen film was measured in vitro. The results indicated bullfrog skin collagen film could be used for sustained release of BSA. Thus, bullfrog skin collagen film can be taken as a novel drug delivery system.

Amino Acids↗

PubMed2004

Use of chemically modified PMMA microspheres for enzyme immobilization.

Modified poly(methyl methacrylate) (PMMA) microspheres, about 7microm in diameter, carrying aldehyde groups on their surfaces were synthesized and used as the support for enzyme immobilization. The immobilizing behavior as well as the properties of immobilized enzyme was studied. The amount of bound enzyme can be extended to 76.8mg g(-1) support, which is relatively much higher than other supports. The kinetic investigation derived from three typical models shows that the practical process is more complicated than the ideal condition, with one or more interactions being involved in the immobilization process. The K(m) value is actually larger and V(max) is smaller in the immobilized form than those in the free form. The increased resistance of the immobilized enzyme against the changes of temperature indicates that immobilizing enzyme onto the modified microspheres is useful for enzyme immobilization.

Adsorption↗

PubMed2004

Technological advances in high-throughput screening.

High-throughput screening (HTS) is the process of testing a large number of diverse chemical structures against disease targets to identify 'hits'. Compared to traditional drug screening methods, HTS is characterized by its simplicity, rapidness, low cost, and high efficiency, taking the ligand-target interactions as the principle, as well as leading to a higher information harvest. As a multidisciplinary field, HTS involves an automated operation-platform, highly sensitive testing system, specific screening model (in vitro), an abundant components library, and a data acquisition and processing system. Various technologies, especially the novel technologies such as fluorescence, nuclear-magnetic resonance, affinity chromatography, surface plasmon resonance, and DNA microarray, are now available, and the screening of more than 100,000 samples per day is already possible. Fluorescence-based assays include the scintillation proximity assay, time-resolved energy transfer, fluorescence anisotropy, fluorescence correlation spectroscopy, and fluorescence fluctuation spectroscopy. Fluorescence-based techniques are likely to be among the most important detection approaches used for HTS due to their high sensitivity and amenability to automation, giving the industry-wide drive to simplify, miniaturize, and speed up assays. The application of NMR technology to HTS is another recent trend in drug research. One advantage afforded by NMR technology is that it can provide direct information on the affinity of the screening compounds and the binding location of protein. The structure-activity relationship acquired from NMR analysis can sharpen the library design, which will be very important in furnishing HTS with well-defined drug candidates. Affinity chromatography used for library screening will provide the information on the fundamental processes of drug action, such as absorption, distribution, excretion, and receptor activation; also the eluting curve can give directly the possibility of candidate drug. SPR can measure the quantity of a complex formed between two molecules in real-time without the need for fluorescent or radioisotopic labels. SPR is capable of characterizing unmodified biopharmaceuticals, studying the interaction of drug candidates with macromolecular targets, and identifying binding partners during ligand fishing experiments. DNA microarrays can be used in HTS be used to further investigate the expression of biological targets associated with human disease, which then opens new and exciting opportunities for drug discovery. Without doubt, the addition of new technologies will further increase the application of HTS in drug screening and its related fields.

Animals↗