Multifunctional Receptor with Tunable Selectivity: A Comparative Recognition Profile of Organic Nanoparticles with Carbon Dots

Structural Features of Carbon Dots and Their Agricultural Potential

Carbon dots (CDs) have drawn attention due to their enticing physical, chemical, and surface properties. Besides, good conductivity, low toxicity, environmental friendliness, simple synthetic routes, and comparable optical properties are advantageous features of CDs. Further, recently, CDs have been explored for biological systems, including plants. Among biological systems, only plants form the basis for sustainability and life on Earth. In this Review, we reviewed suitable properties and applications of CDs, such as promoting the growth of agricultural plants, disease resistance, stress tolerance, and target transportation. Summing up the available studies, we believe that the applications of CDs are yet to be explored significantly for innovation and technology-based agriculture.

Rationally Designed Matrix-Free Carbon Dots with Wavelength-Tunable Room-Temperature Phosphorescence

We report the rational design of the matrix-free carbon dots (C-dots) with long wavelength and wavelength-tunable room-temperature phosphorescence (RTP). Taking advantage of microwave-assisted heating treatment, three RTP C-dots in boric acid (BA) composites are synthesized by using diethylenetriaminepentakis (methylphosphonic acid) as a multiple-sites crosslink agent, a moderately acid catalyst and P source; phenylenediamines (either o-PD, m-PD, or p-PD, respectively) as building block while BA as a carbonization-retardant matrix. After the water-soluble BA matrix is removed by dialysis, three matrix-free C-dots are obtained with RTP emission at 540, 550 and 570 nm under an excitation wavelength of 365 nm. Alterations of RTP emission of three matrix-free C-dots are ascribed to the difference in their particle size and band gap from n-π* transition. Furthermore, the application of three matrix-free C-dots are successfully performed in information encryption and decryption.

Explicating the molecular level drug-polymer interactions at the interface of supersaturated solution of the model drug: Albendazole

Supersaturation as a formulation principle relates to the aqueous solubility of poorly soluble drugs in solution . However, supersaturation state of drugs tends to crystallize because of its thermodynamic instability thereby compromising the solubility and biopharmaceutical performance of drugs. The present study aims to investigate the supersaturation potential of albendazole (ABZ) and its precipitation via nucleation and crystal growth. We hypothesized the use of polymers will avoid ABZ precipitation by interacting with drug molecules. The drug polymer interactions are characterized using conventional methods of Fourier transform infrared (FTIR), Nuclear magnetic resonance (NMR) and Polarized light microscopy (PLM). We have used a novel approach of sum frequency generation (SFG) vibrational spectroscopic in exploring the drug polymer interactions at air-water interface. Recently we have reported the SFG for e rifaximin-polymer interactions (Singh et al., 2021). The supersaturation assay, saturation solubility studies and nucleation induction time analysis revealed polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP K30) as effective precipitation inhibitors thereby enhancing the ABZ equilibrium solubility and in vitro supersaturation maintenance of ABZ. Further, modification in the solid state of ABZ has confirmed the influence of polymers on its precipitation behaviour. We conclude that PVA and PVP K30 act as nucleation and crystal growth inhibitor, respectively for the precipitation inhibition of ABZ.

Elucidating the Molecular Mechanism of Drug-Polymer Interplay in a Polymeric Supersaturated System of Rifaximin

Supersaturated drug delivery system (SDDS) enables the solubility and sustained membrane transport of poorly water-soluble drugs. SDDS provides higher drug concentration in the dispersed phase and equilibrium in the continuous phase, which corresponds to amorphous solubility of the drug. Rifaximin (RFX) is a nonabsorbable BCS class IV drug approved for the treatment of irritable bowel syndrome and effective against Helicobacter pylori. RFX shows slow crystallization and precipitation in an acidic pH of 1.2-2, leading to obliteration of its activity in the gastrointestinal tract. The objective of the present study is to inhibit the precipitation of RFX, involving screening of polymers at different concentrations, using an in-house developed microarray plate method and solubility studies which set forth hydroxypropyl methylcellulose (HPMC) E15, Soluplus, and polyvinyl alcohol to be effective precipitation inhibitors (PIs). Drug-polymer precipitates (PPTS) are examined for surface morphology by scanning electron microscopy, solid-phase transformation by hot stage microscopy, the nature of PPTS by polarized light microscopy, and drug-polymer interactions by Fourier transform infrared and nuclear magnetic resonance spectroscopy. Besides, the unfathomed molecular mechanism of drug-polymer interplay is discerned at the air-water interface using sum-frequency generation spectroscopy to correlate the interfacial hydrogen bonding properties in bulk water. Surprisingly, all studies disseminate HPMC E15 and Soluplus as effective PIs of RFX.