Carbon Dot Biopolymer-Based Flexible Functional Films for Antioxidant and Food Monitoring Applications

Abstract

Heteroatom-doped carbon dot (CD)-reinforced flexible, antioxidant, and UV-resistant polymeric thin films have been fabricated by a facile physical compounding strategy associated with the ‘cast and peel’ technique. The prepared CDs were found to be stable in aqueous media because of their zeta potential value (−5.85 mV). There was no significant change in the zeta potential values during 7 days of storage, indicating the long-term stability of CPCDs. CD-reinforced thermoplastic starch (TPS)/κ-carrageenan hybrid films have been developed as antioxidants to improve the shelf-life of agro-products. Besides this, they also qualified for mechanical strength (>40 MPa), transparency (∼77%), nondeteriorative dimensional integrity at a high relative humidity (∼97%), and UV-resistant properties. For assessing the food preservation behavior, the leaching of CDs also has been studied by time-dependent sustained release in different food simulant media, where it showed a gradual alteration of entrapment efficacy in high-polarity gradient environments. The mechanism of CD release has been obtained from the non-Fickian fittings of the initial preplateaued kinetic data. Surprisingly, when these nanodots were arrested inside the polymer matrix, the film also showed excellent water vapor impermeability, low moisture retention, sufficient toughness, and superficial compliance to external flexing and stretching. Also, CD-based TPS/κ-carrageenan films exhibited strong antioxidant activity, as determined by 1,1-diphenyl-2-picrylhydrazyl (>85%) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid assays (>90%). Thus, these hybrid films could be promoted as ideal alternatives for food packaging with their thin, flexible, tough, antioxidant, and moisture-impermeable properties.

Bioimaging Probes Based on Magneto-Fluorescent Nanoparticles

“…Several different kinds of fluorescent NPs have emerged for bioimaging over the past few decades. These include organic-dye-doped silica NPs, organic polymer NPs, metallic NPs, carbon-based NPs (nanotubes and nanodots) [ 57 ], quantum dots (QDs) [ 58 , 59 , 60 ], and lanthanide-doped upconverting nanoparticles (UCNPs) [ 61 , 62 , 63 ]. In terms of their composition, fluorescent NPs employed in bioimaging may be roughly divided into two categories: organic and inorganic NPs.…”

Eco-Friendly and Sustainable Pathways to Photoluminescent Carbon Quantum Dots (CQDs)

“…Graphene quantum dots (GQDs) are widely regarded as a present-generation carbon material owing to their exceptional optical and electrical properties that are suitable for many technological and energy production fields [ 34 , 35 , 36 ]; insight into recent advances in the greener assembly of GQDs is presented in this overview. As has been examined in the literature, the size of GQDs has an inordinate influence on their operation in different energy appliances; nonetheless, a systematic study that is inclusive of their size is still needed in the future.…”

“…The various means of exploiting carbon precursors to generate CQDs are discussed in detail, along with the evaluation of their future outlook. Adding to the existing literature [ 34 , 35 , 36 ], this review will serve as a resource for methodologies to synthesize novel carbonaceous materials, particularly GQDs, following the precepts of green chemistry. There are several review papers on the title of carbon quantum dots, but our paper collectively highlights the recent synthetic advancements in the creation of the graphene quantum dots during the past 10 years (2012–2021); a compilation of the previous 7 years of research in this field, in a very readable and an easy-to-understand format, is emphasized.…”

Ultrasmall and highly biocompatible carbon dots derived from natural plant with amelioration against acute kidney injury

“…On the one hand, based on the ultra-small size (< 10 nm in general) and unique surface structures, many of reported CDs almost pass through the barrier systems in the state of pathological or normal, accurate in the target organ and provide specific bioactivities to the syndromes [ 13 , 14 ]. The prussian blue-based CDs [ 15 ], selenium-doped CDs [ 16 ] and graphene-based CDs [ 17 ] can remove the ROS and alleviate the degree of AKI, which may be correlated with their surface structure as H-atom donors for ROS trapping [ 18 ]. On the other hand, the chemically synthesized CDs with the complex manipulation and chemical reagent contaminating properties have a certain obstruction in the clinical translation.…”