Comprehensive evaluation of carboxylated nanodiamond as a topical drug delivery system

Abstract

The best strategy in the development of topical drug delivery systems may be to facilitate the permeation of drugs without any harmful effects, while staying on the skin surface and maintaining stability of the system. Nanodiamonds (NDs) play a key role with their excellent physicochemical properties, including high biocompatibility, physical adsorption, reactive oxygen species (ROS) scavenging capability, and photostabilizing activity. Z -average sizes of carboxylated ND (ND–COOH) agglutinate decreased significantly as the pH increased. Fluorescein-conjugated ND was observed only on the stratum corneum, and no sample diffused into the dermal layer even after 48 hours. Moreover, ND–COOH and ND–COOH/eugenol complex did not show significant toxic effects on murine macrophage cells. ND improved in vitro skin permeation >50% acting as a “drug reservoir” to maintain a high drug concentration in the donor chamber, which was supported by quartz crystal microbalance results. Moreover, ND–COOH could adsorb a drug amount equivalent to 80% of its own weight. A photostability study showed that ND–COOH increased the photostability ~47% with regard to rate constant of the eugenol itself. A significant decrease in ROS was observed in the ND–COOH and ND–COOH/eugenol complex compared with the negative control during intracellular ROS assay. Moreover, ROS and cupric reducing antioxidant capacity evaluation showed that ND–COOH had synergistic effects of antioxidation with eugenol. Therefore, ND–COOH could be used as an excellent topical drug delivery system with improved permeability, higher stability, and minimized safety issue.

A simple procedure to obtain nanodiamonds from leftover of HFCVD system for biological application

“…The C(1S) peak was deconvoluted to 3 values of binding energy: 533.6 (C-OH), 532.1 (C=O) and 530.8 (Si). These results indicated the high density of carboxyl groups which was in line with the XPS characterization of carboxylated NDs reported by other researchers [25,50]. The presence of Si identified in the wide scan and in the deconvoluted C(1S) was assigned to the presence of amorphous Si that could be remaining contamination of the Si substrate used to grow the raw diamond.…”

Facile Amine Termination of Nanodiamond Particles and Their Surface Reaction Dynamics

“…Figure 2c shows a comparative analysis of the O 1s spectrum with three deconvoluted curves that confirm the presence of C–O (533.3 eV), C=O (531.4 eV), and O–H (532.9 eV) groups on both untreated and surface-treated UDD. 57,58 Compared to the untreated sample [Figure 2c(i)], a relative reduction of C=O and O–H groups is observed for the treated one. However, the presence of C–O groups remains almost unchanged.…”

Inhibitory effect of carboxylated nanodiamond on oral pathogenic bacteria Streptococcus mutans

“…The cND has one main kind of chemical group on the surface (i.e., the carboxyl group), and it demonstrates good physicochemical properties such as physical adsorption, photostability, and biocompatibility, which will improve permeability, increase stability, and minimize safety issues. 29 Wehling et al 17 and Hees et al 30 performed complex surface modification of NDs in their studies, which may have resulted in many oxygen groups on the surface, providing great convenience for the potentially broad applications of cND.…”