title: In vitro release of lysozyme from gelatin microspheres: effect of cross-linking agents and thermoreversible gel as suspending medium.
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.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Cagliari, CNBS and CSGI, Cittadella Universitaria, s.s. 554 bivio Sestu, 09042 Monserrato (CA), Italy.
authors.forename: Pradip
authors.initials: P
authors.lastname: Hiwale
authors.forename: Sandrina
authors.initials: S
authors.lastname: Lampis
authors.forename: Gabriele
authors.initials: G
authors.lastname: Conti
authors.forename: Carla
authors.initials: C
authors.lastname: Caddeo
authors.forename: Sergio
authors.initials: S
authors.lastname: Murgia
authors.forename: Anna M
authors.initials: AM
authors.lastname: Fadda
authors.forename: Maura
authors.initials: M
authors.lastname: Monduzzi
mesh_terms: D000818:Animals; D002645:Chickens; D003432:Cross-Linking Reagents / Q000737:chemistry; D003692:Delayed-Action Preparations / Q000138:chemical synthesis* / Q000378:metabolism; D004337:Drug Carriers / Q000138:chemical synthesis* / Q000378:metabolism; D005079:Excipients / Q000737:chemistry; D005780:Gelatin / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry; D005976:Glutaral / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D009113:Muramidase / Q000032:analysis / Q000378:metabolism; D010316:Particle Size; D044367:Phase Transition; D020442:Poloxamer / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D003432:Cross-Linking Reagents; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D005079:Excipients; D005782:Gels; D020442:Poloxamer; D005780:Gelatin; D009113:Muramidase; D005947:Glucose; D005976:Glutaral