A Novel Hollow Hydroxyapatite Microspheres/Chitosan Composite Drug Carrier for Controlled Release

doi:10.15541/jim20150488

Abstract

Abstract:

A novel composite drug carrier with excellent sustained and pH-sensitive release performance was prepared by mixing hollow hydroxyapatite (HA) microspheres and chitosan solution with pH-sensitive characteristics. The hollow HA microspheres with mesopores filled on their multilayered spherical shell were obtained by converting borate glass with a novel composition of 19Na₂O-17CaO-64B₂O₃(wt%). The structure, phase composition and morphology of HA microspheres were characterized by SEM, SEM-EDS, XRD, FTIR and N₂ adsorption-desorption measurements. The results indicated that the HA microspheres were B-type carbonated HA with hollow structure, in which the carbonate ions occupied the phosphate sites. The drug release results indicated that the HA microspheres generated burst release at initial stage. Coating the hollow HA microspheres with chitosan (CS) reduced the vancomycin release amount and release rate significantly. Meanwhile, the release profile of vancomycin into PBS with different pH value indicated that the CS-coated composite drug carrier shows pH-sensitive release property. The cumulative percentage of vancomycin released into PBS from the CS (20 g/L)-coated composite drug carrier was 85.63%, 65.85% and 71.85% for pH 6.0, 7.4, 8.5, respectively.

Key words: hollow hydroxyapatite (HA) microspheres, composite drug carrier, pH-sensitive, chitosan

CLC Number:

TQ171

ZHU Kai-Ping, SUN Jing, YE Song, ZHOU Jie, WANG Hui, WANG De-Ping. A Novel Hollow Hydroxyapatite Microspheres/Chitosan Composite Drug Carrier for Controlled Release[J]. Journal of Inorganic Materials, 2016, 31(4): 434-442.

Figures/Tables 12

Fig. 1 SEM image of the as-prepared microspheres with a cross-section in the inset

Fig. 2 Surface SEM images of the hollow HA microspheres (a) Dried at 60℃; (b) Sintered at 600℃ The inset in (a) and (b) show the high magnification image of the surface

Fig. 3 The N2 adsorption-desorption isotherm (a) and the pore size distribution (b) of the microspheres treated at different temperatures

Table 1 The surface characteristics and pore structure parameters of the microspheres

Sample	SA/(m²·g^-1)	PV/(cm³·g^-1)	PS/nm
60℃	55.32	0.21	15.38
600℃	31.17	0.17	28.29

Fig. 4 XRD patterns (a) and FTIR spectrum (b) of the microspheres treated at different temperatures

Fig. 5 EDS spectrum of the shell wall of the hollow HA microspheres (a) Select location (black frame) of the EDS; (b) EDS spectrum

Fig. 6 XRD patterns (a) and FTIR spectra (b) of the CS-coated composite drug carrier

Fig. 7 SEM images of the surface and the cross-section of the CS-coated composite drug carrier (a) Surface of the CS (20 g/L)-coated; (b) Cross-section of the CS (20 g/L)- coated; (c) Surface of the CS (30 g/L)-coated; (d) Cross-section of the CS (30 g/L)-coated

Fig. 8 The cumulative release percentage of vancomycin from the hollow HA microspheres, CS (20 g/L)-coated and CS (30 g/L)-coated composite drug carrier into PBS as a function of time

Fig. 9 The cumulative release percentage of vancomycin into PBS with different pH from the hollow HA microspheres (a), the CS (20 g/L)- coated composite drug carrier (b) and the CS (30 g/L)-coated composite drug carrier (c)

Fig. 10 Physical photos of the CS (20 g/L)-coated composite drug carrier at special time points immersing in PBS with different pH

Fig. 11 SEM image of the CS (20 g/L)-coated HA microspheres after immersing in PBS with the high pH 8.5. Red arrows indicate the hollow HA microspheres; black arrows indicate the chitosan gel

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