Biomolecular interaction analysis for carbon nanotubes and for biocompatibility prediction

Coconut Carbon Dots: Progressive Large-Scale Synthesis, Detailed Biological Activities and Smart Sensing Aptitudes towards Tyrosine

In the recent era, carbon dots (C-dots) have been extensively considered as a potential tool in drug delivery analysis. However, there have been fewer reports in the literature on their application in the sensing of amino acids. As part of our ongoing research on coconut-husk-derived C-dots, we synthesized C-dots under different temperature conditions and utilized them in the field of amino acid sensing and found them to be highly selective and sensitive towards tyrosine. The detailed characterization of the prepared C-dots was carried out. The developed C-dots exhibit good values of quantum yield. BSA, HSA and glutamic acid were utilized to explore the binding efficiency of C-dots with biologically active components. Hemolysis, blood clotting index activity and cell viability assays using the prepared C-dots were evaluated and they were found to be biocompatible. Therefore, the C-dots described in this work have high potential to be utilized in the field of amino acid sensing, especially L-tyrosine. The limit of detection and the binding constant for the developed C-dots in the presence of tyrosine were found to be 0.96 nM and 296.38 nM-1, respectively. The efficiency of the developed C-dots was also investigated in the presence of various other amino acids and different water mediums in order to enhance the working scope of the developed sensors.

In situ photocrosslinkable formulation of nanocomposites based on multi-walled carbon nanotubes and formononetin for potential application in spinal cord injury treatment

Carbon nanotubes (CN) have been studied to treat spinal cord injuries because of its electrical properties and nanometric dimensions. This work aims to develop a photopolymerizable hydrogel containing CN functionalized with an anti-inflammatory molecule to be used in situ on spinal cord injuries. The CN functionalization step was done using the drug (formononetin). The nanocomposites were characterized by morphological analysis, FTIR, Raman Spectroscopy, thermal analysis and cytotoxicity assays (MTT and HET-CAM). The nanocomposites were incorporated into gelatin methacryloyl hydrogel and exposed to UV light for photopolymerization. The volume of the formulation and the UV exposition time were also analyzed. The CN characterization showed that formononetin acted as a functionalization agent. The functionalized CN showed safe characteristics and can be incorporated in photocrosslinkable formulation. The UV exposition time for the formulation photopolymerization was compatible with the cell viability and also occurred in the injury site.

Recent Advances in Carbon Nanotubes for Nervous Tissue Regeneration

Regenerative medicine has taken advantage of several nanomaterials for reparation of diseased or damaged tissues in the nervous system involved in memory, cognition, and movement. Electrical, thermal, mechanical, and biocompatibility aspects of carbon-based nanomaterials (nanotubes, graphene, fullerenes, and their derivatives) make them suitable candidates to drive nerve tissue repair and stimulation. This review article focuses on key recent advances on the use of carbon nanotube- (CNT-) based technologies on nerve tissue engineering, outlining how neurons interact with CNT interfaces for promoting neuronal differentiation, growth and network reconstruction. CNTs still represent strong candidates for use in therapies of neurodegenerative pathologies and spinal cord injuries.

Capillary electrophoresis analysis of affinity to assess carboxylation of multi-walled carbon nanotubes

Surface oxidation improves the dispersion of carbon nanotubes in aqueous solutions and plays a key role in the development of biosensors, electrochemical detectors and polymer composites. Accurate characterization of the carbon nanotube surface is important because the development of these nano-based applications depends on the degree of functionalization, in particular the amount of carboxylation. Affinity capillary electrophoresis is used to characterize the oxidation of multi-walled carbon nanotubes. A polytryptophan peptide that contains a single arginine residue (WRWWWW) serves as a receptor in affinity capillary electrophoresis to assess the degree of carboxylation. The formation of peptide-nanotube receptor-ligand complex was detected with a UV absorbance detector. Apparent dissociation constants (K_D) are obtained by observing the migration shift of the WRWWWW peptide through background electrolyte at increasing concentrations of multi-walled carbon nanotubes. A 20% relative standard deviation in method reproducibility and repeatability is determined with triplicate analysis within a single sample preparation and across multiple sample preparations for a commercially available carbon nanotube. Affinity capillary electrophoresis is applied to assess differences in degree of carboxylation across two manufacturers and to analyze acid treated carbon nanotubes. The results of these studies are compared to X-ray photoelectron spectroscopy and zeta potential. Affinity capillary electrophoresis comparisons of carbon nanotube samples prepared by varying acid treatment time from 30 min to 3 h yielded significant differences in degree of carboxylation. X-ray photoelectron spectroscopy analysis was inconclusive due to potential acid contamination, while zeta potential showed no change based on surface charge. This work is significant to research involving carbon nanotube-based applications because it provides a new metric to rapidly characterize carbon nanotubes obtained from different vendors, or synthesized in laboratories using different procedures.