Emissive carbon dots derived from natural liquid fuels and its biological sensing for copper ions

Single-atom nanozymes shines diagnostics of gastrointestinal diseases

Various clinical symptoms of digestive system, such as infectious, inflammatory, and malignant disorders, have a profound impact on the quality of life and overall health of patients. Therefore, the chase for more potent medicines is both highly significant and urgent. Nanozymes, a novel class of nanomaterials, amalgamate the biological properties of nanomaterials with the catalytic activity of enzymes, and have been engineered for various biomedical applications, including complex gastrointestinal diseases (GI). Particularly, because of their distinctive metal coordination structure and ability to maximize atom use efficiency, single-atom nanozymes (SAzymes) with atomically scattered metal centers are becoming a more viable substitute for natural enzymes. Traditional nanozyme design strategies are no longer able to meet the current requirements for efficient and diverse SAzymes design due to the diversification and complexity of preparation processes. As a result, this review emphasizes the design concept and the synthesis strategy of SAzymes, and corresponding bioenzyme-like activities, such as superoxide dismutase (SOD), peroxidase (POD), oxidase (OXD), catalase (CAT), and glutathione peroxidase (GPx). Then the various application of SAzymes in GI illnesses are summarized, which should encourage further research into nanozymes to achieve better application characteristics.

Green synthesis of multifunctional carbon quantum dots: An approach in cancer theranostics

Carbon quantum dots (CQDs) have gained significant growing attention in the recent past due to their peculiar characteristics including smaller size, high surface area, photoluminescence, chemical stability, facile synthesis and functionalization possibilities. They are carbon nanostructures having less than 10 nm size with fluorescent properties. In recent years, the scientific community is curiously adopting biomass precursors for the preparation of CQDs over the chemical compounds. These biomass sources are sustainable, eco-friendly, inexpensive, widely available and convert waste into valuable materials. Hence in our work the fundamental understating of diverse fabrication methodologies of CQDs, and the types of raw materials employed in recent times, are all examined and correlated comprehensively. Their unique combination of remarkable properties, together with the ease with which they can be fabricated, makes CQDs as promising materials for applications in diverse biomedical fields, in particular for bio-imaging, targeted drug delivery and phototherapy for cancer treatment. The mechanism for luminescence is of considerable significance for leading the synthesis of CQDs with tunable fluorescence emission. Therefore, it is aimed to explore and provide an updated review on (i) the recent progress on the different synthesis methods of biomass-derived CQDs, (ii) the contribution of surface states or functional groups on the luminescence origin and (iii) its potential application for cancer theranostics, concentrating on their fluorescence properties. Finally, we explored the challenges in modification for the synthesis of CQDs from biomass derivatives and the future scope of CQDs in phototherapy for cancer theranostics.

Natural Carbon Nanodots: Toxicity Assessment and Theranostic Biological Application

This review outlines the methods for preparing carbon dots (CDs) from various natural resources to select the process to produce CDs with the best biological application efficacy. The oxidative activity of CDs mainly involves photo-induced cell damage and the destruction of biofilm matrices through the production of reactive oxygen species (ROS), thereby causing cell auto-apoptosis. Recent research has found that CDs derived from organic carbon sources can treat cancer cells as effectively as conventional drugs without causing damage to normal cells. CDs obtained by heating a natural carbon source inherit properties similar to the carbon source from which they are derived. Importantly, these characteristics can be exploited to perform non-invasive targeted therapy on human cancers, avoiding the harm caused to the human body by conventional treatments. CDs are attractive for large-scale clinical applications. Water, herbs, plants, and probiotics are ideal carbon-containing sources that can be used to synthesize therapeutic and diagnostic CDs that have become the focus of attention due to their excellent light stability, fluorescence, good biocompatibility, and low toxicity. They can be applied as biosensors, bioimaging, diagnosis, and treatment applications. These advantages make CDs attractive for large-scale clinical application, providing new technologies and methods for disease occurrence, diagnosis, and treatment research.

Dual-Mode Fluorescence and Visual Fluorescent Test Paper Detection of Copper Ions and EDTA

In this study, blue-emission carbon dots were prepared from the legumes of the vegetable Pisum sativum Linn. by one-step carbonization. The fluorescence of a carbon dot (CDs) solution can be quenched by copper ions and recovered by ethylenediaminetetraacetic acid (EDTA). In addition, two kinds of visual fluorescent filter papers were prepared. Finally, a dual-mode fluorescence and visual fluorescent test paper was employed for the detection of copper ions and EDTA. The simple synthesis method and the high safety enable this material to have more application possibilities.

Synthesis, Characterization and Ecotoxicity Evaluation of Biochar-Derived Carbon Dots from Spruce Tree, Purple Moor-Grass and African Oil Palm

Biochar-derived C-Dots from Picea, Molinia caerulea and Elaeis guineensis were synthesized through a hydrothermal process, and their physicochemical and optical characteristics and environmental effects were compared. These C-Dots were characterized by techniques such as Attenuated Total Reflection–Fourier Transform Infrared (ATR-FTIR), UV-Vis spectrophotometry, fluorescence spectroscopy, dynamic light scattering (DLS), Z potential, and High-Resolution Transmission Electronical Microscopy (HR-TEM). The ecotoxicity tests were performed using the Microtox™ test, making this study one of the few that use this method. The C-Dots from Molinia caerulea showed the best quantum yield (QY) of 8.39% and moderate ecotoxicity, while Elaeis guineensis has the lowest QY (2.31%) but with zero toxicity. Furthermore, the C-Dots from Picea presents good optical properties but showed high toxicity and limits its use. Finally, all C-Dots showed functional groups that could be biofunctionalized with biomolecules, especially C-Dots from Molinia caerulea and Elaeis guineensis show potential for use in the development of optical biosensors.

Upcycling of plastic waste into fluorescent carbon dots: An environmentally viable transformation to biocompatible C-dots with potential prospective in analytical applications

The profitable impact on ecological system made the upcycling of plastic waste as one of the captivating issues in scientific world. The current work highlights the sustainable approach to transform the plastic waste comprises of bottles, used cups and polyethylene bags via simple heating to fluorescent carbon dots (C-dots). The obtained C-dots have displayed the absorption peaks around at 260 nm with size ranging between 5 and 30 nm. The upcycling has produced the structural changes in plastic waste and affected the optical properties of C-dots. The three types of used plastic waste as precursor have displayed excellent emission properties with peak positioned around 422 nm and quantum yield (QY) values ∼62, 65 and 64% for C-dots generated from plastic polybags, cups and bottles (P-CDs, C-CDs and B-CDs) respectively. The toxicity profiling of C-dots has been successfully tested by employing multi-assay biocompatible activities i.e. antibacterial and antifungal activities. The potential prospective of C-dots derived from plastic waste have further been explored in analytical applications involving selective copper metal ion sensing in aqueous media. The outcomes of the current studies have highlighted the potential accomplishment in preserving environment fate and giving response towards the budding social hitch of plastic waste.

A dicyanomethylene-4H-pyran-based fluorescence probe with high selectivity and sensitivity for detecting copper (II) and its bioimaging in living cells and tissue

Copper (Cu) plays a significant role in the process of oxygenic photosynthesis in living systems. The detection of copper ion (Cu²⁺) is valuable and meaningful for further investigating the functions of Cu²⁺ under physiological and pathological conditions. In this paper, a novel fluorescence probe DCM-Cu based on the near-infrared (NIR) fluorophore dicyanomethylene-4H-pyran (DCM) was designed for Cu²⁺ detection. The probe DCM-Cu possessed characteristic of "turn-on" fluorescent signal in the presence of Cu²⁺ through the enhanced ICT process. It exhibited satisfactory sensitivity and selectivity toward Cu²⁺. A good linear correlation was observed between the concentrations of Cu²⁺ and the fluorescence intensities at 700 nm. The detection limit (LOD) of DCM-Cu toward Cu²⁺ was calculated to be 2.54 × 10^-8 M. Importantly, DCM-Cu was successfully applied in the detection of Cu²⁺ in living MCF-7 cells and tumor tissue with low cytotoxicity. Therefore, this probe would have the potential to monitor cellular Cu²⁺ in the living system and be applied to the diagnosis of related diseases.

Orange emissive carbon nanodots for fluorescent and colorimetric bimodal discrimination of Cu2+ and pH

We have facilely synthesized orange emissive carbon nanodots (O-CDs) via a hydrothermal method using citric acid and 5-aminosalicylic acid.

Carbon dots as versatile nanoarchitectures for the treatment of neurological disorders and their theranostic applications: A review

The development of novel methods plays a fundamental role in early diagnosis and controlling of neurological disorders (NDs). Blood-brain barrier (BBB) is the most challenging barrier for the development of neuro drug delivery systems due to its inhibiting ability to enter drugs and agents into central nervous system (CNS). Carbon dots (CDs) have shown to be very promising and outstanding agents for various biomedical applications (bio imaging studies, treatment of NDs and brain tumors). They exhibit remarkable properties such as biocompatibility, small size (less than 10 nm, enabling penetration into BBB), tunable optical properties, photostability and simple synthetic procedures, allowing them to act as ideal candidates in various fields of science. Therefore, the objective of this review is to overview the recent studies on CDs for the development of neuro drug delivery systems to reach CNS via crossing of BBB. Primarily, this review briefly outlines the unique optical properties and toxicity of CDs. The development of novel neuro drug delivery systems for various neurological disorders using CDs as carriers is described. This review also covers the potential applications of CDs in brain tumors imaging and treatment of neurodegenerative diseases. Finally, the sensing applications and future prospects of CDs are summarized.