Effect of the Structural and Morphological Properties of Surfactant-Assisted Hydroxyapatite on Dermal Irritation and Antibacterial Activity.

Giovanni García Domínguez,Joan Reyes Miranda,Aristeo Garrido Hernández,Sebastián Diaz De La Torre,Lorena Chávez Güitrón,Maribel Quezada Cruz,Erasto Vergara Hernández

doi:10.3390/ma14216522

Abstract

Hydroxyapatite (HAp) nanoparticles with a homogeneous rod morphology were successfully synthesized using the hydrothermal method. The powders were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The antibacterial and dermal irritation analyses of the samples were performed and discussed. The use of cationic and anionic surfactants, namely, cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), respectively, at a low concentration (2.5 mol%) modified the length/diameter (L/D) ratio of the HAp rods. Structural characterizations of hydroxyapatite synthesized without surfactant (HA), with 2.5 and 5 mol% of SDS (SDS− and SDS+, respectively), and with 2.5 and 5 mol% of CTAB (CTAB− and CTAB+, respectively) revealed well-crystallized samples in the hexagonal phase. The CTAB− sample presented antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Streptococcus anginosus, Staphylococcus aureus, Micrococcus luteus, and Klebsiella pneumoniae, suggesting that antimicrobial susceptibility was promoted by the bacterial nature and the use of the surfactant. Dermal irritation showed no clinical signs of disease in rabbits during the study, where there was neither erythema nor necrosis at the inoculation sites.

Highlights

In orthopedic surgery, hydroxyapatite (Ca10 (PO4 )6 (OH)2 ) is the most used material due to its highly similar chemical composition to the inorganic part of the human bone and stability under physiological conditions [1,2]
The results indicated that the antibacterial and dermal irritation properties depended on the length/diameter (L/D) ratio of the HAp particles
The surfactants that were used during the synthesis did not change the crystal structure; the main diffraction peaks presented a difference in their relative intensities, especially for the (002) and (211) planes

Summary

Introduction

Hydroxyapatite (Ca10 (PO4 ) (OH)2 ) is the most used material due to its highly similar chemical composition to the inorganic part of the human bone and stability under physiological conditions [1,2]. Hydroxyapatite (Hap) has been used as a bio-coating on metal implants in the human body, offering high biocompatibility; it has a wide range of applications regarding bone tissue engineering, dental prostheses, thin-film coating, bone defects, and bone replacements In addition to their use in bone-related engineering, HAp-based materials offer a wide range of biological applications, such as drug delivery, protein cleavage, and gene transfer, mainly due to their benign nature [3,4,5]. For all these uses, like other biomaterials, the studies on skin irritation are important for evaluating biological safety, which validated the potential application of HAp powders. Osteomyelitis, which is usually caused by Staphylococcus aureus (S. aureus), causes many complications regarding trauma and orthopedic surgery [9]

Methods

Results

Conclusion