Supercritical Fluid Facilitated Disintegration of Hexagonal Boron Nitride Nanosheets to Quantum Dots and Its Application in Cells Imaging

Abstract

Preparation of quantum dots (QDs) and exfoliation of two-dimensional layered materials have gathered significant attention in recent days. Though, there are number of attempts have been reported, facile and efficient methodology is yet to be explored. Here, we demonstrate supercritical fluid processing approach for rapid and facile synthesis of blue luminescent BN QDs from layered bulk material via in situ exfoliation followed by disintegration. The microscopic and AFM analysis confirmed the few layer BN QDs formation. The strong luminescent behavior of BN QDs is utilized to stain Gram-negative bacterial cells specifically in the presence of Gram-positive bacterial cells.

Supercritical Fluid‐Facilitated Exfoliation and Processing of 2D Materials

“…[141] Texter claimed that the best solvents from a wetting perspective are those that satisfy the inequality: γ 2D > γ sol + γ 2D/sol , where γ 2D is the Gibbs surface energy of a 2D material, γ sol is the surface energy (surface tension) of a solvent (a Gibbs free energy that can be readily measured), and γ 2D/sol is the interfacial energy of the solvent/2D www.advancedscience.com Adv. [141] However, only a few of these solvents such as high-boiling-point NMP and DMF have been employed under supercritical and near critical conditions for exfoliating graphite, [131][132][133] layered titanate, [61] NH 4 MPO 4 ·H 2 O (M = Fe, Mn, Co, Ni), [60] MoS 2 , [56,143] MoSe 2 , [56] BN, [144] and BN-MoS 2 heterostructure. 2019, 6,1901084 [61] material interface (that can be estimated from contact angle measurement).…”

“…[144,241] Anthracite coal was demonstrated by Poulin and co-workers as a source of nanosheets using an scH 2 O process (374 °C, 22.1 MPa) that was mildly oxidizing. [144,241] Anthracite coal was demonstrated by Poulin and co-workers as a source of nanosheets using an scH 2 O process (374 °C, 22.1 MPa) that was mildly oxidizing.…”

“…Under certain supercritical conditions, GO nanosheets were obtained as 3 nm diameter quantum dots in high yield (55%). [144] They reported a mechanism that proceeded through nanosheet formation by exfoliation followed by nanosheet disintegration into QDs. A separate scEtOH process (241 °C, 6.1 MPa) that was mildly reducing was found to produce graphenic ribbonlike nanosheets at 6.8% yield.…”

“…[241] These GO QDs were evaluated as labels in HeLa cells and found not to exhibit toxicity at up to 40 µg mL −1 and to provide a distinct blue fluorescence after 24-h incubation with these cells. [144] These ribbons produced electrically conducting films with a surface conductivity of about 0.1 mS/◽.…”

Supercritical‐Fluid‐Assisted Decoration of MoS2 @ MWCNTs and Their Superior Performance in the Electrochemical Hydrogen Evolution Reaction

“…It has been efficiently used for synthesis of various semiconductor materials with narrow particle size distribution. In addition, synthesis/exfoliation/functionalization/disintegration of 2D inorganic layered materials were carried out in a short reaction time, recently . The synthesis and exfoliation process was very rapid in SCF method since the fluid has gas‐like diffusivity and liquid‐like solvent properties along with low interfacial tension, excellent wetting of surfaces and high diffusion coefficients .…”