Alkaline N-GQDs fluorescent probe for the ultrasensitive detection of creatinine.

Creatinine (Crn) is an important excretory product of the human body. Medical laboratory technology has improved over years and brought many advancements in clinical diagnostics equipment, and testing techniques and made the tests more efficient. Yet, the quantitative analysis of Crn is still carried out by the classical Jaffe's reaction (using Picric acid (PA) with NaOH) method. Since PA is hazardous to human health, alternative solutions such as; nanoparticles and surface-modified nanoparticles can be used. Exploring the optoelectronic properties of carbon-based quantum dots for biomolecule sensing is of current interest among researchers. Nitrogen functionalized graphene quantum dots (Alk-NGQDs) measured featured Crn easier and reduced the time taken for the test carried out in laboratories. The synthesized Alk-NGQDs optical, structural, morphological properties, surface and compositions are studied through XPS, HRTEM, XRD, FTIR, and spectroscopic techniques. Alk-NGQDs at alkaline conditions (pH 9.5) form a stable complex with Crn through intermolecular charge transfer (ICT). The fluorescence titration method is used to sense Crn in commercial Crn samples and human blood serum. To understand the efficacy of sensing creatinine using Alk-NGQDs, working concentration, fluorescence quantum yield, the limit of detection, and quenching constant are calculated using the Stern-Volmer plot. The emission property of Alk-NGQDs is aimed to bring an alternative to the traditional colorimetric Jaffe's reaction.

Do amino acid functionalization stratagems on carbonaceous quantum dots imply multiple applications? A comprehensive review.

Amino acids are the noteworthy entity among biological molecules with diverse properties such as zwitterionic and amphoteric. Functionalizing carbon-based quantum dots using amino acids might be used for the extreme enhancement of electronic and optical properties of quantum dots and improve the performance of the resultant amino acid-functionalized quantum dots. The amino acid-functionalized quantum dots are highly soluble, sustainable, and biocompatible with virtuous optical and electrical performance, which makes them potential and suitable candidates for fabricating optoelectronic devices. The tenacity of using amino acids as functional groups to functionalize quantum dots and their novel properties are conferred to attain their multiple applications. The goal of this review is to provide the choices of amino acids based on the desired applications and a variety of functionalization techniques to make them a noteworthy material for future applications. The method of one-step and two-step functionalization strategies along with the properties of the resultant functionalized quantum dots and their plausible applications and future scope of the material are highlighted. Amidation is the basic principle behind the functionalization of quantum dots with amino acids. This review would be an exciting prospect to explore the pathways of the possible applications in different domains, in which the amino acid-functionalized quantum dots have not yet been explored. Further, this review article helps in pitching a variety of prominent applications right from sensors to energy storage systems either using the optical property or electronic property of amino acid-functionalized quantum dots.

Correlation of micellar aggregation - complexation regimes to discern stability of micellar structure and nano-encapsulation.

HYPOTHESIS: The physico-chemical mechanisms associated reverse micelle based encapsulation processes deserve investigation owing to the direct correlation between stability of micellar structure and nano encapsulation. The presence of core nanoparticles is expected to influence the stability of micellar structure when the concentrations of surfactant and particle concentration are varied. Hence, it should be possible to define the micellar aggregation - complexation regimes and systematic measurements have robust implications for nano encapsulation. EXPERIMENTS: Reverse micelle systems stabilized by non-ionic surfactant are formulated with the presence of core nanoparticles. Micellar aggregation and complexation processes are analyzed in two different oil phase (n-hexane and n-butanol). The regimes are probed by measuring average hydrodynamic diameter of reverse micelle, optical transmittance and specific conductivity. Shell encapsulation experiments are performed in aggregation and complexation regimes. FINDINGS: When the concentration of surfactant increases, reverse micelle size increases (to dia ∼ 200 nm). This is a reversal of the otherwise reported trend wherein the core is absent. Breakdown of stable reverse micellar structure obstructs shell coating and this is a first attempt to analyze micellar aggregation - complexation regimes with the presence of core. Reverse micelle breakage or complexation is to be completely avoided to achieve core@shell nanoparticles.

Modified spin-coating technique to achieve directional colloidal crystallization.

Fabricating large single crystals with colloidal spheres as building blocks is challenging and of competitive interest. Spin-coating of colloids offers a robust technique, which is highly reproducible in obtaining colloidal crystals even at fast dynamical regimes; however, these crystals are intrinsically polycrystalline due to the axial symmetry of spin-coating. We report a new method that applies a nonuniform electric field during the spin-coating process. By arranging the field direction to be stationary in the rotating frame, we are able to break the axial symmetry and to orient the colloids along one predefined direction. By regulating the applied field strength, we demonstrate local control over the orientation of the crystallites, and thus, the orientation is determined by the applied field strength.