Zinc oxide nanocrystals as a nanoantibiotic and osteoinductive agent

Abstract

In this paper we aim to analyse the behaviour of ZnO nanocrystals (ZnO NCs), prepared with a new synthetic approach and not embedded in any composite matrix, for bone implant applications in vitro. In particular, we have developed a novel, fast and reproducible microwave-assisted synthesis, to obtain highly-crystalline, round-shaped ZnO NCs of 20 nm in diameter as an extremely-stable colloidal solution in ethanol. The nanocrystals were also partially chemically functionalized by anchoring amino-propyl groups to the ZnO surface (ZnO–NH2 NCs). Thus, the role of both ZnO NC concentration and surface chemistry were tested in terms of biocompatibility towards pre-osteoblast cells, promotion of cell proliferation and differentiation, and also in terms of antimicrobial activity against Gram positive and negative bacteria, such as Escherichia coli and Staphylococcus aureus, respectively. The results suggest that ZnO–NH2 NCs is the most promising candidate to solve infectious disease in bone implants and at the same time promote bone tissue proliferation, even at high concentrations. Although further investigations are needed to clarify the mechanism underlying the inhibition of biofilm formation and to investigate the role of the ZnO–NH2 NCs in in vivo assays, we demonstrated that fine and reproducible control over the chemical and structural parameters in ZnO nanomaterials can open up new horizons in the use of functionalized ZnO NCs as a highly biocompatible and osteoinductive nanoantibiotic agent for bone tissue engineering.

Phytogreen synthesis of multifunctional nano selenium with antibacterial and antioxidant implications

“…Briefly, acidified KMnO 4 solution (0.630 mM, 10 ml) was prepared in 0.5 M H 2 SO 4 . Simultaneously, ascorbic acid standard solutions of varying concentrations (1,4,8,12,16, and 20 μg ml −1 ) were also prepared. Then, 0.1 ml of KMnO 4 was added to 1 ml of ascorbic acid solutions and incubated at room temperature for 5 min.…”

“…In this regard, different metallic nanoparticles (NPs) including silver (Ag) [4][5][6], gold (Au) [7], zinc (Zn) [8], selenium (Se) [9,10], titanium [11], ceria [12] have been explored [13]. Se is an essential metalloid element that has been extensively used in medical applications owing to its antioxidative, antimicrobial and antitumor activities [14].…”

Leveraging metal oxide nanoparticles for bacteria tracing and eradicating

“…For example, the modulation of size, morphology, and surface of ZnO nanoparticles was demonstrated to effectively control the sterilizing effect, although their antibacterial mechanisms remain controversial. 68 In this section, we mainly focus on how physicochemical characteristic influence the functionality and application of the commonly used metal oxide nanoparticles.…”

Biodegradable and Drug-Eluting Inorganic Composites Based on Mesoporous Zinc Oxide for Urinary Stent Applications

“…ZnO is a “generally recognized as safe” (GRAS), white, odorless inorganic solid compound. ZnO also exhibits intrinsic antibacterial properties [ 30 ], thereby paving the way to its possible use as intrinsically-antimicrobial material. The antibacterial activity of ZnO is mainly ascribed to the following mechanisms [ 31 ]: reactive oxygen species (ROS) generation, release of Zn 2+ cations, and electrostatic interactions between ZnO nanomaterials and the bacterial surface.…”

“…Despite the potential role in determining ZnO antibacterial efficacy, the release of Zn 2+ ions can also induce undesirable cytotoxicity against healthy cells and their release must be properly optimized and monitored to guarantee biocompatibility at the same time [ 29 , 32 ]. Especially for biomedical implants or drug delivery devices, the control over ZnO particle size, morphology, interparticle porosity and surface chemistry is crucial to achieve antibacterial properties and biocompatibility towards healthy cells at the same time [ 30 ]. Another important aspect of ZnO is its biodegradability, as it is easily soluble in water solution at pH below 5.5 or in water solution rich in salts, such as phosphates [ 33 ].…”