Hydroxyapatite (HA) is widely used in bone tissue engineering for its bioactivity and biocompatibility, and a growing number of researchers are exploring ways to improve the physical properties and biological functions of hydroxyapatite. Up to now, HA has been used as inorganic building blocks for tissue engineering or as nanofillers to blend with polymers, furthermore, various methods such as ion doping or surface modification have been also reported to prepare functionalized HA. In this review, we try to give a brief and comprehensive introduction about HA-based materials, including ion-doped HA, HA/polymer composites and surface modified HA and their applications in bone tissue engineering. In addition, the prospective of HA is also discussed. This review may be helpful for researchers to get a general understanding about the development of hydroxyapatite based materials.

Chiral gold nanoparticles (Au NPs) have been investigated widely and have shown great potential in biomedical applications, such as biosensing, combating bacterial infections and tissue regeneration. However, some stabilizers and reducing agents for the synthesis of chiral Au NPs can produce toxicity in living organisms. Therefore, it is interesting to design green methods to prepare chiral gold nanoparticles that are nontoxic, environment-friendly, and low-cost. Herein, novel biocompatible chiral Au NPs with a diameter of 54.4 ± 14.9 nm were prepared by the in situ reduction of HAuCl₄ with alginates as the green reducing agent and chiral-inducing and stabilizing agent. XPS, TGA, UV-Vis and CD analyses demonstrated that alginate-stabilized chiral Au NPs (ALG-Au NPs) were successfully prepared, while biocompatibility assessment showed that cell viability was 116.0% when the concentration of ALG-Au NPs arrived at 300 μg/mL, which indicated that ALG-AuNPs showed excellent biocompatibility. Furthermore, the ALG-Au NPs can respond to metal ions, such as Ca²⁺, Cu²⁺, Mn²⁺ and so on, implying potential application for biosensing.