Iron-doped Nano-hydroxyapatite: Preparation and Ultraviolet Absorption Performance

doi:10.15541/jim20240413

Abstract

Abstract:

Nano-hydroxyapatite (nHAP) possesses both biocompatibility and environmental friendliness, and holds the potential to become a novel ultraviolet (UV) absorbent material following iron doping modification. This study employed co-precipitation and hydrothermal methods to prepare iron-doped nano-hydroxyapatite (Fe-nHAP). Influence of the preparation process on UV absorption performance was investigated by adjusting reaction time, temperature, and iron doping ratio. The results indicate that with the increase of temperature from 37 ℃ to 150 ℃ or the extension of reaction time from 0.5 h to 3 h, both the crystallinity and the peak of UV absorption improve. It can be inferred that there is a certain positive correlation between the UV absorption performance and crystallinity of Fe-nHAP. Additionally, the UV absorption capacity is closely correlated to the iron doping ratio. As the iron doping molar ratio increases from 0 to 10%, the UV absorption capacity is gradually enhanced, with the maximum absorption value rising from 0.03 to 1.35. This phenomenon is attributed to the reduction in optical bandgap caused by iron doping. However, a high iron doping ratio leads to excessive reduction in material crystallinity, resulting in weakened enhancement of UV absorption performance. The safety assessment indicates that Fe-nHAP with an iron doping molar ratio of 7% does not demonstrate cytotoxicity, phototoxicity and skin irritation. In summary, Fe-nHAP has a suitable UV absorption performance. With its favorable biosecurity, it is anticipated to emerge as a new type of UV absorption material.

Key words: nano-hydroxyapatite, iron doping, ultraviolet absorption

CLC Number:

TQ174

AN Ran, LIN Si, GUO Shigang, ZHANG Chong, ZHU Shun, HAN Yingchao. Iron-doped Nano-hydroxyapatite: Preparation and Ultraviolet Absorption Performance[J]. Journal of Inorganic Materials, 2025, 40(5): 457-465.

Figures/Tables 14

Fig. 1 XRD patterns of as-prepared Fe-nHAP (a) 37-150 ℃, 3 h, 1%Fe-nHAP; (b) 150 ℃, 0.5-3 h, 1%Fe-nHAP; (c) 150 ℃, 3 h, 0-10%Fe

Table 1 Lattice parameters, volumes, crystallinities, and grain sizes of Fe-nHAP prepared under different temperatures (T)

T/℃	a-axis/Å	c-axis/Å	Volume/Å³	Crystallinity/%	D₍₀₀₂₎/nm	D₍₃₁₀₎/nm
37	9.39411	6.80010	525.23	19.56	43.50	20.11
60	9.39522	6.80268	525.54	21.25	49.66	20.30
80	9.39580	6.82520	525.46	25.56	54.33	20.33
100	9.39954	6.84554	526.65	30.77	57.28	21.05
150	9.40185	6.86230	526.90	32.00	61.50	25.49

Table 2 Lattice parameters, volumes, crystallinities, and grain sizes of Fe-nHAP prepared for different time

Time/h	a-axis/Å	c-axis/Å	Volume/Å³	Crystallinity/%	D₍₀₀₂₎/nm	D₍₃₁₀₎/nm
0.5	9.32063	6.77150	525.11	16.77	46.72	23.05
1	9.32145	6.79534	525.45	20.70	49.52	23.21
3	9.32498	6.82841	526.55	32.13	61.08	25.44
5	9.32705	6.83254	526.73	33.06	62.01	25.54

Table 3 Lattice parameters, volumes, crystallinities, and grain sizes of Fe-nHAP with Fe doped at different molar ratios

Sample	a-axis/Å	c-axis/Å	Volume/Å³	Crystallinity/%	D₍₀₀₂₎/nm	D₍₃₁₀₎/nm
nHAP	9.33129	6.70756	527.13	43.92	70.79	31.45
0.3%Fe-nHAP	9.33089	6.70422	526.85	38.71	65.22	26.68
1%Fe-nHAP	9.32652	6.70033	526.21	32.04	61.12	25.44
3%Fe-nHAP	9.32421	6.69054	526.06	32.10	60.46	25.29
7%Fe-nHAP	9.32056	6.68135	525.98	30.36	56.23	25.10
10%Fe-nHAP	9.32001	6.68045	525.73	27.77	55.28	25.12

Fig. 2 FT-IR spectra of Fe-nHAP (150 ℃, 3 h, 0-10%Fe)

Fig. 3 TEM images of Fe-nHAP (150 ℃, 3 h, 0-10%Fe) with insets showing corresponding HRTEM images (a) nHAP; (b) 0.3%Fe-nHAP; (c) 1%Fe-nHAP; (d) 3%Fe-nHAP; (e) 7%Fe-nHAP; (f) 10%Fe-nHAP

Table 4 Elemental composition (%, mass fraction) of Fe-nHAP (150 ℃, 3 h, 0-10%Fe)

Element	nHAP	0.3%Fe-nHAP	1%Fe-nHAP	3%Fe-nHAP	7%Fe-nHAP	10%Fe-nHAP
Ca	37.11176	38.84537	38.44196	37.46884	34.68688	32.83218
P	17.12133	18.47263	18.33874	18.44668	18.06182	17.50755
Fe	0.00589	0.22444	0.69487	2.04870	4.65011	6.35854

Fig. 4 (a) UV absorption performance of 1%Fe-nHAP prepared under different temperatures; (b) UV absorption performance of 1%Fe-nHAP prepared for different time; (c) Relationship between crystallinity and UV absorption performance of 1%Fe-nHAP

Fig. 5 (a) UV absorption performance of different materials; (b) Effect of iron doping ratio on crystallinity and UV absorption performance of Fe-nHAP; (c) Tauc curves of different materials

Fig. 6 XPS spectra and UV absorption spectra of different materials (a) nHAP; (b) 7%Fe-nHAP; (c) 10%Fe-nHAP; (d) Fine Fe2p orbital spectrum of 7%Fe-nHAP; (e) Fine Fe2p orbital spectrum of 10%Fe-nHAP; (f) UV absorption performance of two valence states of Fe in 7%Fe-nHAP

Fig. 7 Hydrophobicity of Fe-nHAP (0-10%Fe)

Table 5 Test results of Fe-nHAP on 4 heavy metals and 5 microorganisms

Test item	Concentration/ (mg·kg^-1)	Limit/ (mg·kg^-1)
Hg	0.002	1
Pb	0.05	10
As	0.01	2
Cd	0.18	5
Total colony count	-	500
Yeasts and molds count	-	100
T-E. coli	-	0
Staphylococcus aureus	-	0
Pseudomonas aeruginosa	-	0

Fig. 8 Cell compatibilities of Fe-nHAP (0-10%Fe) (a, b) Cell viability after being cultured for (a) 2 and (b) 4 d at different concentrations; (c) Cell dead/live staining after being cultured at a concentration of 200 μg/mL. Colorful figures are available on website

Fig. 9 Skin irritation comparison test of 7%Fe-nHAP (a, b) Before application; (c, d) After 14 d

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