A green path to extract carbon quantum dots by coconut water:Another fluorescent probe towards Fe^(3+) ions

In recent years,carbon quantum dots(CQDs)have been of great enthrallment in the fluorescent probe field.Carbon precursors with interesting physicochemical properties may be derived from natural sources.In this research,for the first time,coconut water has been used as a source of carbon to prepare blue fluorescent CQDs without any modification and functionalization.The preparation of CQDs is very simple and cost-effective,when compared with other conventional techniques.The reaction parameters temperature and pH were varied to obtain monodispersed spherical CQDs with an average grain size of ∼5 nm.The CQDs exhibit blue emission with a wavelength of 487 nm with an excitation wavelength of 390 nm and are used for Fe^(3+) ions detection.Fe^(3+) ions have been observed to quench the fluorescence intensity of the CQDs than other heavy metals.In the presence of Fe^(3+) ions,the fluorescent CQDs are quenched due to the interaction of CQDs and Fe^(3+) ions.A spectroscopic result shows that Fe^(3+) ions can be observed within a concentration of 0-700μM,as well as the detection limit is 0.30μM.The CQDs provide a unique pathway for potential application in the environmental monitoring of heavy metal ions.

Dual functional AgNPs-M13 phage composite serves as antibacterial film and sensing probe for monitoring the corrosion of chromium-containing dental alloys

The preparation of silver nanoparticles(AgNPs)with microbe or plant tissues as bio-template offers green approach,while it suffers from low harvest and purification is needed.Herein,we propose a facile protocol for one-pot preparation of AgNPs using M13 phage as bio-template by simply mixing AgN03 solution with alkali M13 phage.In the obtained AgNPs-M13 phage composite,Cr(Ⅲ)selectively coordinates with the amino residues on phage surface and leads to the aggregation of AgNPs through the bridging of M13 phages.This makes it feasible for colorimetric sensing of Cr(Ⅲ)by measuring the absorbance ratio of AgNPs at 600 and 405 nm,which provides a LOD of 14 nmol/L.The composite also showed favorable bactericidal activity for both Gram-positive and Gram-negative bacteria,making it a promising candidate as antibacterial film in chromium-containing dental alloys and meanwhile serve as a sensing probe for monitoring the corrosion of the dental alloys.

Efficient removal of chlorophenols from water with a magnetic reduced graphene oxide composite

A magnetic reduced graphene oxide composite(MRGO) was successfully prepared by a simple and green method. MRGO was then used as an adsorbent and found to exhibit enhanced removal efficiency for various chlorophenols(CPs) from water compared with its precursors, graphene oxide(GO) and reduced graphene oxide. The CPs were o-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. Among them, 2,4,6-trichlorophenol, which exhibited the lowest water solubility and highest molecular weight, most easily bound to MRGO. The preferential interactions between MRGO and CPs were hydrophobic interactions(?-? stacking and hydrophobic effect). This result was confirmed by the equilibrium adsorption behavior in which isotherms were all well described by Freudlich model, indicating heterogeneous and multilayer adsorption. Therefore, CP adsorption was more favored under neutral and acidic conditions, and the decreased removal efficiency of MRGO at higher p H levels was due to the improved hydrophilicity of CPs for deprotonation effect. Moreover, MRGO showed fast removal of each CP, achieving adsorption equilibrium within 10.0 min, presented efficient separation from water under an external magnetic field, and was easily regenerated using dilute Na OH aqueous solution after reaching saturated adsorption. Adsorption capacity of the regenerated MRGO had almost no loss until after five cycles. In summary, MRGO was an efficient adsorbent for the removal of various CPs and had considerable application potential in water treatment.