Porous Hydroxyapatite Microspheres Prepared by Using Poly (Allylamine Hydrochloride) and Its Application in Drug Delivery

doi:10.15541/jim20170041

Abstract

Abstract:

Porous and hollow hydroxyapatite (HAP) microspheres were synthesized successfully in hydrothermal method utilizing poly(allylamine hydrochloride) (PAH) as the crystal growth regulator. Effects of reaction time and concentration of the polymer on the growth of final products were investigated. Uniform microspheres with dense pores can be synthesized by controlling the PAH concentration (0.3-0.5 g/L) after 12 h hydrothermal reaction at 150℃. Formation of hollow microspheres includes different stages of early precursor microstructures, heterogeneous nucleation and phase transformations. At different stages, the cationic polyelectrolyte PAH plays an important role in regulating growth of hollow microspheres. Ibuprofen (IBU) was chosen as a typical model drug to study the drug loading and the desorption ability. The results show that porous and hollow microspheres have relatively high drug loading capacity (413.65 mg/g). Drug release of the microspheres is favorably pH-responsive, which may have close relationship with the surface properties of HAP nanorods. Date from this study suggest that the porous microspheres will have potential application as the targeted-drug carrier in the biomedicine field.

Key words: hydroxyapatite, poly(allylamine hydrochloride), porous microspheres, hydrothermal method, drug carrier

CLC Number:

TQ174

MA Fang, CUI Ming-Fang, ZHU Jian-Hua, LI Ya-Li. Porous Hydroxyapatite Microspheres Prepared by Using Poly (Allylamine Hydrochloride) and Its Application in Drug Delivery[J]. Journal of Inorganic Materials, 2017, 32(11): 1215-1222.

Figures/Tables 15

Fig. 1 Structural formula of PAH

Fig. 2 Optical images of “vesicles” after addition of Na2HPO4 with PAH (0.42 g/L) (a) “Vesicles” before introduction of calcium ions; (b) Aggregations after addition of Ca2+; (c) Polarized image after adding Ca2+

Fig. 3 Diameter distributions of "vesicles", which were synthesized by 0.42 g/L PAH and disodium hydrogen phosphate solution before adding calcium ions (a) and calcium phosphate "vesicle structure" after adding calcium ions (b)

Fig. 4 Zeta potential of "vesicles" before introduction of calcium ions (a); Zeta potential of nucleated particles after addition of calcium ions (b)([PAH]=0.42 g/L)

Fig. 5 SEM images of the HAP samples after reacting for different time (a) 0.5 h; (b) 1.5 h; (c) 8 h; (d) 12 h

Fig. 6 TEM (a) and HRTEM images (b) of samples after hydrothermally reacting for 1.5 h

Fig. 7 XRD patterns of HAP samples after being reacted for various time (a) 0.5 h; (b) 1.5 h; (c) 8 h; (d) 12 h; (e) 0 h

Fig. 8 FTIR spectra of the products synthesized by hydrthermal method for different time (a) 0 h; (b) 0.5 h; (c) 1.5 h; (d) 8 h; (e) 12 h

Fig. 9 TEM (a, b) and HRTEM (c) images of HAP microspheres after reacting for 12 h. Inset in (c) shows the selected area diffraction (SAED) pattern([PAH]=0.42 g/L)

Fig. 10 SEM images of the HAP samples synthesized by hydrothermal method with different PAH concentrations (a) 0 g/L; (b) 0.06 g/L; (c) 0.06 g/L; (d) 0.24 g/L; (e) 0.36 g/L; (f) 0.42 g/L

Fig. 11 XRD patterns of the HAP samples synthesized by hydrothermal method with different PAH concentrations (a) 0.06 g/L; (b) 0.24 g/L; (c) 0.36 g/L; (d) 0.42 g/L

Fig. 12 Illustration for the strategy of HAP porous microsphere

Fig. 13 N2 adsorption-desorption isotherm and the pore size distribution of HAP porous microspheres prepared by a hydrothermal method at 150℃ for 12 h

Fig. 14 UV-Vis spectra of IBU before (a) and after (b) adsorption onto the surface of porous microspheres, UV-Vis spectrum of IBU in the PBS solution after releasing for 6 h (c)

Fig. 15 IBU release profiles of porous microspheres in PBS solution of pH at 4.0, 5.6 and 7.4, under 37℃

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