In vitro release of lysozyme from gelatin microspheres: effect of cross-linking agents and thermoreversible gel as suspending medium

Biomacromolecules. 2011 Sep 12;12(9):3186-93. doi: 10.1021/bm200679w. Epub 2011 Aug 11.

Abstract

This study was aimed to characterize the microstructure and the performance of gelatin microspheres (GMs) cross-linked by two different cross-linkers viz. d-glucose and glutaraldehyde. New formulations were obtained, suspending the GMs in a thermoreversible Pluronic F127 (PF127) liquid-crystalline gel. Lysozyme was used as a model biomacromolecular drug to evaluate release features. Both types of cross-linked GMs were prepared by thermal gelation method. The lysozyme-loaded microspheres were characterized by scanning electron microscopy (SEM) for size distribution, shape, and surface texture. SEM revealed that both types of lysozyme-loaded GMs were spherical in shape and that the surface of glutaraldehyde cross-linked GMs was smoother than that of the glucose cross-linked GMs. The degree of cross-linking of microspheres was investigated using ATR-FTIR technique. The prepared GMs were suspended in 20% w/v aqueous PF127 gel for which the usual sol-gel transition temperature of 22 °C did not change in the presence of GMs, as indicated by rheological measurements. SAXS study of the PF127 gel confirmed the occurrence of a discrete cubic liquid-crystalline phase of the Fm3m type whose lattice parameter slightly decreased as a result of GMs addition. The in vitro release of lysozyme from both types of cross-linked GMs was successfully controlled when they were suspended in PF127 gel, thus suggesting the potential use of this new combined formulation as a drug-depot system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chickens
  • Cross-Linking Reagents / chemistry
  • Delayed-Action Preparations / chemical synthesis*
  • Delayed-Action Preparations / metabolism
  • Drug Carriers / chemical synthesis*
  • Drug Carriers / metabolism
  • Excipients / chemistry
  • Gelatin / chemistry*
  • Gels / chemistry*
  • Glucose / chemistry
  • Glutaral / chemistry
  • Microscopy, Electron, Scanning
  • Microspheres
  • Muramidase* / analysis
  • Muramidase* / metabolism
  • Particle Size
  • Phase Transition
  • Poloxamer / chemistry
  • Spectroscopy, Fourier Transform Infrared
  • Temperature

Substances

  • Cross-Linking Reagents
  • Delayed-Action Preparations
  • Drug Carriers
  • Excipients
  • Gels
  • Poloxamer
  • Gelatin
  • Muramidase
  • Glucose
  • Glutaral