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

Abstract

Nanodiamonds (NDs) are amongst the most investigated carbon-based nanostructures due to their chemical stability and favorable mechanical properties. Despite the number of works on methods for NDs production, one of the main challenges is to achieve their colloidal stability in aqueous suspension. Additionally, NDs are normally obtained by expensive, complex and time-consuming process. Herein, it was presented a facile method to obtain NDs in aqueous suspension by using columnar structure diamond from Hot-Filament Chemical Vapour Deposition reactor (HFCVD). CVD diamond leftover thick film from CVDVale Company was used. Therefore, this method has the advantage of being not only practical but also cost-effective since it brings a profitable use of CVD diamond leftover. The Diamond thick film was submitted to ultrasonic cavitation in the presence and absence of ZrO 2 microbeads in aqueous medium. The NDs hydrodynamic diameter and the stability in aqueous suspension were monitored by light scattering, size and morphology were analyzed by transmission electronic microscopy. Considering the wide application of NDs in biomedical devices, cytotoxicity of aqueous suspensions of NDs was evaluated against murine embryonic fibroblast cells. Furthermore, NDs were functionalized with hydrogen and carboxyl groups. NDs aqueous suspension of straight size distribution was obtained even in the absence of ZrO 2 beads, indicating that they may be dispensable in order to decrease NDs size. NDs of average hydrodynamic diameter of 22 nm and − 35 mV of Zeta-potential were obtained after ultrasonic cavitation followed by 2 h of centrifugation, not demonstrating cytotoxicity to cells at very low (0.05-0.5 μg/mL) nor at higher concentrations (116 μg/mL). Nevertheless, NDs showed a moderate cytotoxicity at intermediary concentration range (0.5-2.2 μg/mL). From our knowledge, this is the first work that reports on a facile method for providing NDs aqueous suspension with high colloidal stability from HFCVD diamond leftover.

Diamond Nanoparticles-Porphyrin mTHPP Conjugate as Photosensitizing Platform: Cytotoxicity and Antibacterial Activity

“…Accordingly, Gismondi et al (2015) [62] also reported cell viability values greater than 80% after incubation of B16-F10 and HeLa cells with detonation ND of 4-5 nm at 200 µg/mL. The low cytotoxicity of ND was also reported in our previous work (Hurtado 2020) [12]. ND of 22-77 nm diameter were obtained from micrometric diamond HFCVD by ultrasonic cavitation.…”

“…The most commonly techniques to produce ND are high pressures and high temperatures (HPHT) [7], plasma-assisted chemical vapor deposition (PACVD), hot filament chemical vapor deposition (HFCVD), explosive detonation [7], laser ablation [3,8,9], and ultrasonic cavitation [10,11]. Recently ND with hydrogenated surface were obtained from leftover of HFCVD system by ultrasonic cavitation [12] and high-energy mill grinding [13]. The ND obtained by explosive detonation have high surface density of oxidized chemical groups that are highly reactive and enable the coupling of different types of molecules [14][15][16][17].…”