Calcium phosphate-alginate microspheres as enzyme delivery matrices

Abstract

The present study concerns the preparation and initial characterisation of nov el calcium titanium phosphate-alginate (CTPalginate) and hydroxyapatite-alginate (HAp-alginate) microspheres, which are intended to be used as enzyme delivery matrices and bone regeneration templates. Microspheres were prepared using different concentrations of polymer solution (1% and 3% w/v) and different ceramic-to-polymer solution ratios (0.1, 0.2 and 0.4 w/w). Ceramic powders were characterised using X-ray diffraction, laser granulometry, Brunauer, Emmel and Teller (BET) method for the determination of surface area, zeta potential and Fourier transform infrared spectroscopy (FT-IR). Alginate was characterised using high performance size exclusion chromatography. The methodology followed in this investigation enabled the preparation of homogeneous microspheres with a uniform size. Studies on the immobilisation and release of the therapeutic enzyme glucocerebrosidase, employed in the treatment of Gaucher disease, were also performed. The enzyme was incorporated into the ceramic-alginate matrix before gel formation in two different ways: preadsorbed onto the ceramic particles or dispersed in the polymeric matrix. The two strategies resulted in distinct release profiles. Slow release was obtained after adsorption of the enzyme to the ceramic powders, prior to preparation of the microspheres. An initial fast release was achiev ed when the enzyme and the ceramic particles were dispersed in the alginate solution before producing the microspheres. The latter profile is very similar to that of alginate microspheres. The different patterns of enzyme release increase the range of possible applications of the system inv estigated in this work.

Preparation of alginate membrane for tissue engineering

“…The stretching vibration peak of C-O of the alginate membrane that appeared at 1266 cm -l was attributed to the reaction between carboxyl and Ca ion ("C-O-Ca-O-CO-" group structure), which enhanced C-O vibration [16]. These changes indicate that Ca ion formed an "egg tray" structure with the sodium alginate molecular chain.…”

Powder Characterization of Calcium Phosphate/Collagen for Bone Implant Application

“…The structure of the CaP/SA particles showed that when there is an increase in the SA content, more flakey structures were formed in the particles caused by the structure of SA particles ( Figure 2). All the combinations showed that the SA was identified with CaP because the SA fully covered the CaP surface [10,13].The EDS results (Figure 2) showed that the sodium (Na) peak was identified in the composite and the extensive peak was formed when a higher wt% of SA added. …”

“…The alginate did not affect the subsequent modification of the characteristic band of calcium titanium phosphate (CTP) and HA.This showed that both ceramics were maintained in the microsphere [13].A study by Kui Zhou showed that porous HA/SA 3D material was formed afterweight loss occurredthrice at 100 O C, 300 to 400 O C and 600-1300 O C respectively.This was confirmed by the DSC-TG graph [15].During the SEM analysis, it was found that the HA particles were homogenously dispersed and well embedded throughout the SA particles [10,13].…”

“…Sodium alginate (SA) is soluble in water and that possesses rheological properties. Sodium alginate has been used as a thickening or gelling agent, colloidal stabilizer and as a blood expander in the pharmaceutical industry for a long time [13]. A combination of CaP and SA was prepared using the precipitation method.…”

Strontium Incorporation on Microspheres of Alginate/β-tricalcium Phosphate as Delivery Matrices

“…However, the poor mechanical properties of β-TCP limit its use to non-load bearing applications 8 . Thus, the combination of inorganic and organic components has been investigated in order to produce composites with physico-chemical characteristics improved when compared to isolated components 9 . Some polymers, such as alginate, are used as polymeric matrix in DDS.…”