Biomedical subjects

Kangjie Zhu

Publications and source records attributed to Kangjie Zhu.

5 recordsLinked to original sources

PubMed2006

Modulation of protein release from biodegradable core-shell structured fibers prepared by coaxial electrospinning.

Biodegradable core-shell structured fibers with poly(epsilon-caprolactone) as shell and bovine serum albumin (BSA)-containing dextran as core were prepared by coaxial electrospinning for incorporation and controlled release of proteins. BSA loading percent in the fibers and its release rate could be conveniently varied by the feed rate of the inner dope during electrospinning. With the increase in the feed rate of the inner dope, there was an associated increase in the loading percent and accelerated release of BSA. Poly(ethylene glycol) (PEG) was added to the shell section of the fibers to further finely modulate the release behavior of BSA. It was revealed that the release rate of BSA increased with the PEG percent in the shell section. By varying the feed rate of the inner dope and PEG content, most of BSA could be released from the core-shell structured fibers within the period of time ranging from 1 week to more than 1 month. The effect of the feed rate of the inner dope and addition of PEG into the shell section on the fiber morphology was also examined by scanning electron microscope.

Absorbable Implants↗

PubMed2005

Biodegradable hyaluronic acid/n-carboxyethyl chitosan/protein ternary complexes as implantable carriers for controlled protein release.

An ampholytic N-carboxyethyl chitosan (CEC), with various isoelectric points (IPs), was synthesized by grafting acrylic acid on chitosan utilizing Michael's reaction. Compared to native chitosan, CEC has enhanced water solubility and dramatically accelerated enzymatic degradation; the rate of degradation is proportional to the degree of substitution (DS). The results from turbidimetric titration and fluorescence studies revealed that CEC formed complexes with either hyaluronic acid (HA) or bovine serum albumin (BSA) within a certain pH range. The HA/CEC/BSA ternary complexes could be prepared by colloid titration with quantitative yield and BSA entrapment. The rate of BSA release from the complexes was affected by pH, ionic strength, DS of CEC, and the molecular weight (MW) of HA. The endurance of BSA release from the complexes could be extended up to 20 d by formulating them with high-MW HA and CEC with low DS.BSA release profiles from HA/CEC-2/BSA complexes.

Absorbable Implants↗

PubMed2005

A facile technique to prepare biodegradable coaxial electrospun nanofibers for controlled release of bioactive agents.

A one-step, mild procedure based on coaxial electrospinning was developed for incorporation and controlled release of two model proteins, BSA and lysozyme, from biodegradable core-shell nanofibers with PCL as shell and protein-containing PEG as core. The thickness of the core and shell could be adjusted by the feed rate of the inner dope, which in turn affected the release profiles of the incorporated proteins. It was revealed that the released lysozyme maintained its structure and bioactivity. The current method may find wide applications for controlled release of proteins and tissue engineering.

Chemistry, Pharmaceutical↗

PubMed2005

Novel copolyanhydrides combining strong inherent fluorescence and a wide range of biodegradability: synthesis, characterization and in vitro degradation.

In this work, a novel diacid monomer was synthesized in a very convenient scheme. The monomer is derived from naturally occurring products and emits strong fluorescence when polymerized to polyanhydride. The chemical structure of the monomer dCPS is as follows: HOC(O)ArOC(O)(CH2)2C(O)O--Ar--COOH. Copolyanhydrides composed of dCPS and sebacic acid were further prepared by melt copolycondensation, and characterized by IR, NMR, UV-Vis, DSC and fluorometry. The emission wavelength (lambda(em)) of the copolymers could be tuned by the excitation wavelength (lambda(ex)). Fluorescence intensity increased with the increase of dCPS content. The microspheres fabricated from the copolymer with dCPS content as low as 10% could be clearly visualized with fluorescence microscopy. Either blue or green images of the microspheres could be captured with an excitation of UV and visible light. The degradation rate of the copolyanhydrides decreased as the dCPS fraction increased, and the degradation duration could be modulated from several days to more than three months. In addition, it was found that the copolyanhydrides displayed surface degradation characteristics. In view of the advantages of the novel copolyanhydrides, such as easy preparation, unique inherent luminescent properties, and widely adjustable degradation rate, they might be useful for biomedical engineering.

Decanoic Acids↗

PubMedDate not supplied

Controlled delivery system for norethindrone based on biodegradable poly-alpha,beta-(hydroxyalkyl)-DL-aspartamide.

The article describes the preparation of poly-(hydroxyalkyl)-DL-aspartamide (PHAA) by a (ring) opening reaction by hydroxyalkylamino; norethindrone (NET), as a model drug, was coupled to the polymers via hydroxyalkylamino spacers. PHAA and NETPHAA conjugates were characterized by FTIR, DSC, x-ray,(13)C NMR, and scanning electron microscopy and their structure were confirmed. The biocompatibility of PHAA was tested. The study showed that PHAA was a hydrophilic, nontoxic in vivo, nonantigenic material and had good biocompatibility as a drug carrier. The effect on drug release from the polymer of length of side chain, initial drug loading, and particle size of the polymer drug were investigated in tris-HCl buffer solution (pH 7.4, t = 37 degrees C). In vivo release in rabbits also was performed for 120 days. The experiment indicated that the concentration of NET in rabbits can be 1-2 microg/ml serum after 1 month; 10% of NET had been released from the polymer.

Animals↗