Microwave-assisted chemical synthesis of conducting polyindole: Study of electrical property using Schottky junction

Polyindole-Derived Nitrogen-Doped Graphene Quantum Dots-Based Electrochemical Sensor for Dopamine Detection

The sensitive monitoring of dopamine levels in the human body is of utmost importance since its abnormal levels can cause a variety of medical and behavioral problems. In this regard, we report the synthesis of nitrogen-doped graphene quantum dots (N-GQDs) from polyindole (PIN) via a facile single-step hydrothermal synthetic strategy that can act as an efficient electrochemical catalyst for the detection of dopamine (DA). The average diameter of N-GQDs was ∼5.2 nm and showed a C/N atomic ratio of ∼2.75%. These N-GQDs exhibit a cyan fluorescence color under irradiation from a 365 nm lamp, while PIN has no characteristic PL. The presence of richly N-doped graphitic lattices in the N-GQDs possibly accounts for the improved catalytic activity of N-GQDs/GCE towards electrocatalytic DA detection. Under optimum conditions, this novel N-GQDs-modified electrode exhibits superior selectivity and sensitivity. Moreover, it could detect as low as 0.15 nM of DA with a linear range of 0.001-1000 µM. In addition, the outstanding sensing attributes of the detector were extended to the real samples as well. Overall, our findings evidence that N-GQDs-based DA electrochemical sensors can be synthesized from PIN precursor and could act as promising EC sensors in medical diagnostic applications.

Indole Carbonized Polymer Dots Boost Full-Color Emission by Regulating Surface State

Carbonized polymer dots (CPDs) are impressive imaging probes with great potential for enriching the library of metal-free fluorescent materials, yet current strategies have struggled to achieve products that emit full-color light in a single reaction system. Establishing an efficient and robust synthesis approach that unlocks the color barrier to the luminescence centers of specific CPDs remains a challenge. Herein, the surface-state engineering of pyridine and amide in the indole system to create a palette of resolvable full-color light-emissive CPDs is reported. Detailed structural analysis revealed that cationic polymerization and oxidation reactions potentially contribute to the formation of the main frameworks and emission centers of the final CPDs, with emissive oxygen- and nitrogen-based centers fixed by cross-linked polymer structures. This study provides valuable insight into the energy absorbance and photoluminescence mechanism of CPDs and introduces additional reactants (benzo heterocycle) into CPD research.

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Achieving a palette of full-color light-emissive CPDs in a single reaction system

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Providing the surface-state engineering rules for CPDs' emission centers

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Enriching the guidance library for studying the fluorescence mechanism of CPDs

In Vitro and in Vivo Antimicrobial Evaluation of Graphene-Polyindole (Gr@PIn) Nanocomposite against Methicillin-Resistant Staphylococcus aureus Pathogen

Nowadays, the infection caused by the methicillin-resistant Staphylococcus aureus (MRSA) and countless different types of bacterial infection cause the death of millions of people worldwide. Thereby, several strategies have explored for the advancement of better and active antimicrobial agents; one of these lies in the form of two-dimensional carbon-based nanocomposites. Herein, we demonstrate the synthesis of the graphene-polyindole (Gr@PIn) nanocomposite and polyindole (PIn) and significantly enhance the proficiency against MRSA strains which are immune to most antibiotics. The synthesized Gr@PIn and PIn have been characterized by the various biophysical techniques, especially X-ray diffraction (XRD), electron microscopy [scanning electron microscopy (SEM) and transmission electron microscopy (TEM)], Fourier transform infrared, Raman, UV-vis spectroscopy, and thermogravimetric analysis. Electron microscopic investigations unveiled the disintegration of bacterial cell wall upon interaction with Gr@PIn. Significantly, the Gr@PIn found to be very potent in the eradication of the MRSA strain with minimal toxicity to the mammalian cells. Assessment of the antibacterial mechanism revealed that the Gr@PIn adhered toward the bacterial surface, irreversibly interrupted the membrane layer structure of the bacteria, eventually penetrated cells, and efficiently impeded protein activity, which inherently turns into bacterial apoptosis in vitro. Moreover, last, the synthesized Gr@PIn efficiently treated the S. aureus-mediated experimental skin infection in BALB/c mice as well. This work magnifies our comprehending antibacterial mechanism of nonmetallic graphene-based PIn nanocomposite and provides the support to activity anticipation.