Citric Acid-Mediated Microwave-Hydrothermal Synthesis of Mesoporous F-Doped HAp Nanorods from Bio-Waste for Biocidal Implant Applications.

Gopalu Karunakaran,Areum Han,Kattakgoundar Govindaraj Sudha,Govindan Suresh Kumar,Eun-Bum Cho,Evgeny Kolesnikov,Shin Sik Choi,Kowsalya Mariyappan

doi:10.3390/nano12030315

Abstract

In this current research, mesoporous nano-hydroxyapatite (HAp) and F-doped hydroxyapatite (FHAp) were effectively obtained through a citric acid-enabled microwave hydrothermal approach. Citric acid was used as a chelating and modifying agent for tuning the structure and porosity of the HAp structure. This is the first report to use citric acid as a modifier for producing mesoporous nano HAp and F-doped FHAp. The obtained samples were characterized by different analyses. The XRD data revealed that F is incorporated well into the HAp crystal structure. The crystallinity of HAp samples was improved and the unit cell volume was lowered with fluorine incorporation. Transmission electron microscopy (TEM) images of the obtained samples revealed that a nano rod-like shape was obtained. The mesoporous structures of the produced HAp samples were confirmed by Brunauer–Emmett–Teller (BET) analysis. In vivo studies performed using zebrafish and C. elegans prove the non-toxic behavior of the synthesized F doped HAp samples. The obtained samples are also analyzed for antimicrobial activity using Gram-negative and Gram-positive bacteria, which are majorly involved in implant failure. The F doped samples revealed excellent bactericidal activity. Hence, this study confirms that the non-toxic and excellent antibacterial mesoporous F doped HAp can be a useful candidate for biocidal implant application.

Highlights

Citric acid was used as a modifier for obtaining HAp nanoparticles
Eggshells were used as a calcium precursor and potassium phosphate for the HAp synthesis
Given that the worms’ eggs have experienced four developmental larval stages until the adult stage, these results demonstrate that those two types of HAp nanomaterials exert no developmental and biological toxicity on C. elegans

Summary

Introduction

Bone regeneration is one of the most interesting fields in reformative medicine in which different calcium-dependent biomaterials are implemented for the recovery of bone [1]. The bone consists of bio-minerals along with its protein matrix, minerals, and water [2]. The biomineral component in bone is mostly hydroxyapatite (HAp) (Ca10 (PO4 ) (OH) ). The HAp has been applied to bone implants because of its similar chemical composition and increased bio-compatibility analogous to that of natural bone. HAp is one of the most stable phases of calcium phosphate and is found in several parts of our body, such as teeth, bone, etc. HAp is one of the most stable phases of calcium phosphate and is found in several parts of our body, such as teeth, bone, etc. [3]

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