A multi-channel array for metal ions discrimination with animal bones derived biomass carbon dots as sensing units

Biomass-derived carbon dots as emerging visual platforms for fluorescent sensing

Biomass-derived carbon dots (CDs) are non-toxic and fluorescently stable, making them suitable for extensive application in fluorescence sensing. The use of cheap and renewable materials not only improves the utilization rate of waste resources, but it is also drawing increasing attention to and interest in the production of biomass-derived CDs. Visual fluorescence detection based on CDs is the focus of current research. This method offers high sensitivity and accuracy and can be used for rapid and accurate determination under complex conditions. This paper describes the biomass precursors of CDs, including plants, animal remains and microorganisms. The factors affecting the use of CDs as fluorescent probes are also discussed, and a brief overview of enhancements made to the preparation process of CDs is provided. In addition, the application prospects and challenges related to biomass-derived CDs are demonstrated.

Seafood waste derived carbon nanomaterials for removal and detection of food safety hazards

Nanobiotechnology and the engineering of nanomaterials are currently the main focus of many researches. Seafood waste carbon nanomaterials (SWCNs) are a renewable resource with large surface area, porous structure, high reactivity, and abundant active sites. They efficiently adsorb food contaminants through π-π conjugated, ion exchange, and electrostatic interaction. Furthermore, SWCNs prepared from seafood waste are rich in N and O functional groups. They have high quantum yield (QY) and excellent fluorescence properties, making them promising materials for the removal and detection of pollutants. It provides an opportunity by which solutions to the long-term challenges of the food industry in assessing food safety, maintaining food quality, detecting contaminants and pretreating samples can be found. In addition, carbon nanomaterials can be used as adsorbents to reduce environmental pollutants and prevent food safety problems from the source. In this paper, the types of SWCNs are reviewed; the synthesis, properties and applications of SWCNs are reviewed and the raw material selection, preparation methods, reaction conditions and formation mechanisms of biomass-based carbon materials are studied in depth. Finally, the advantages of seafood waste carbon and its composite materials in pollutant removal and detection were discussed, and existing problems were pointed out, which provided ideas for the future development and research directions of this interesting and versatile material. Based on the concept of waste pricing and a recycling economy, the aim of this paper is to outline current trends and the future potential to transform residues from the seafood waste sector into valuable biological (nano) materials, and to apply them to food safety.

Determination of carbohydrate content in kenaf degumming wastewater and converting them to carbon dots

The traditional textile degumming process produces abundant wastewater, which contains a lot of monosaccharides and oligosaccharides. It is of great economic and environmental significance to utilize these carbohydrates in high value. In this study, high performance liquid chromatography (HPLC) was used to analyze the carbohydrate components in kenaf degumming wastewater, and then the production of C-dots using the wastewater was explored. The results showed that the types and content in the degumming wastewater were monosaccharides (glucose, xylose and arabinose) and oligosaccharides (dextran, xylan and araban). The carbohydrate (mainly glucan and xylan) content in wastewater accounted for 91.16 % of the total carbohydrates weight loss in kenaf degumming process. By using hydrolysis and hydrothermal reaction on kenaf degumming wastewater, blue-green carbon dots (C-dots) with good performance were prepared and successfully applied to anti-counterfeiting printing. In particular, the as-prepared C-dots prepared from kenaf degumming wastewater with urea added (WUC-dots) showed an excitation-dependent photoluminescence (PL) spectrum and quantum yield (QY) of 2.4 % in aqueous solution. The fluorescent code exhibited a clear outline, excitation-tunable color and good stability, showing a great potential for anti-counterfeiting system.

Biomass derived green carbon dots for sensing applications of effective detection of metallic contaminants in the environment

The rapid consumption of metals and unorganized disposal have led to unprecedented increases in heavy metal ion concentrations in the ecosystem, which disrupts environmental homeostasis and results in agricultural biodiversity loss. Mitigation and remediation plans for heavy metal pollution are largely dependent on the discovery of cost-effective, biocompatible, specific, and robust detectors because conventional methods involve sophisticated electronics and sample preparation procedures. Carbon dots (CDs) have gained significant importance in sensing applications related to environmental sustainability. Fluorescence sensor applications have been enhanced by their distinctive spectral properties and the potential for developing efficient photonic devices. With the recent development of biomass-functionalized carbon dots, a wide spectrum of multivalent and bivalent transition metal ions responsible for water quality degradation can be detected with high efficiency and minimal toxicity. This review explores the various methods of manufacturing carbon dots and the biochemical mechanisms involved in metal detection using green carbon dots for sensing applications involving Cu (II), Fe (III), Hg (II), and Cr (VI) ions in aqueous systems. A detailed discussion of practical challenges and future recommendations is presented to identify feasible design routes.

An overview on animal/human biomass-derived carbon dots for optical sensing and bioimaging applications

Over the past decade, carbon dots (CDs) have emerged as some of the extremely popular carbon nanostructures for diverse applications. The advantages of sustainable CDs, characterized by their exceptional photoluminescence (PL), high water solubility/dispersibility, non-toxicity, and biocompatibility, substantiate their potential for a wide range of applications in sensing and biology. Moreover, nature offers plant- and animal-derived precursors for the sustainable synthesis of CDs and their doped variants. These sources are not only readily accessible, inexpensive, and renewable but are also environmentally benign green biomass. This review article presents in detail the production of sustainable CDs from various animal and human biomass through bottom-up synthetic methods, including hydrothermal, microwave, microwave-hydrothermal, and pyrolysis methods. The resulting CDs exhibit a uniform size distribution, possibility of heteroatom doping, surface passivation, and remarkable excitation wavelength-dependent/independent emission and up-conversion PL characteristics. Consequently, these CDs have been successfully utilized in multiple applications, such as bioimaging and the detection of various analytes, including heavy metal ions. Finally, a comprehensive assessment is presented, highlighting the prospects and challenges associated with animal/human biomass-derived CDs for multifaceted applications.

One-Pot Hydrothermal Method Preparation of Cerium-Nitrogen-Codoped Carbon Quantum Dots from Waste Longan Nucleus as a Fluorescent Sensor for Sensing Drug Rifampicin

Currently, the large-scale application of carbon quantum dots (CQDs) is usually limited by their low quantum yield and detection limit. Herein, the abandoned longan nucleus was used as a carbon source to synthesize cerium-nitrogen-codoped carbon quantum dots (Ce/N-CQDs) with strong luminescence intensity. In this work, the fluorescent properties and fluorescent quantum yield of CQDs may be improved by the single cerium-doped carbon quantum dots (Ce-CQDs) and the single nitrogen-doped carbon quantum dots (N-CQDs). Nevertheless, the Ce/N-CQDs exhibited intense fluorescence with a high quantum yield. Compared with CQDs, the quantum yield of Ce/N-CQDs was significantly increased from 5 to 32% and showed high photostability and good water solubility. The Ce/N-CQDs can be used for the direct detection of rifampicin (RFP) in human serum. The concentration demonstrated a good linear relationship in the range of 1.0 × 10-7-9.0 × 10-6 mol/L, with a detection limit of 9.6 × 10-8 mol/L.

Quantitative detection of captopril in urine by smartphone-assisted ratiometric fluorescence sensing platform

Captopril (CP) is a widely used antihypertensive drug. In this study, a smartphone-assisted sensing platform on the basis of ratiometric fluorescent test strips was developed, which can accomplish visualization for the quantitative detection of captopril. Ratiometric fluorescent probe was constructed from carbon dots (CDs) and gold nanoclusters (Au NCs). After adding Cu²⁺ to fluorescent probe, Cu²⁺ can complex the amino and carboxyl groups on the surface of Au NCs and aggregate Au NCs, which will quench the fluorescence of Au NCs. Compared with amino and carboxyl groups, -SH in CP has a higher affinity for Cu²⁺ and can capture Cu²⁺ to restore Au NCs fluorescence. In this process, CDs remained essentially unchanged as background fluorescence. As CP concentration increased, the fluorescence color showed a distinct change from blue to purple to orange. Based on this principle, a sensing platform combining smartphone and fluorescent test strips was constructed to visualize the quantitative detection of CP by RGB values. Under optimal conditions, the wide linear range of CP detection for both fluorescence spectrometer and smartphone paper-based sensing platform was 0.25-50 μM. The limits of detection were as low as 76 nM and 101.3 nM, respectively. Furthermore, it was implemented successfully for the detection of CP in urine. The satisfactory recoveries were 96.0-103.3% and 92.0-108.0% for fluorescence spectrometer and smartphone platform, respectively. This smartphone-assisted platform provided a new approach for visual detection of CP, which showed its great potential in bioanalytical assays.

A Review on the Use of Biochar Derived Carbon Quantum Dots Production for Sensing Applications

Since their discovery, carbon dots have attracted a great deal of interest for their perspective biological applications. Nevertheless, the quenching of carbon dots photoluminescence represents an interesting feature for quantitative analysis in very low concentration of many species. A particular approach for the production of carbon dots is the use of biochar, a carbonized biomass, as a precursor. In this work, we overview the main achievements accomplished by using biochar-derived carbon dots for detecting and quantifying inorganic and organic species. We also provide background knowledge of the main properties, production and purification routes of carbon dots.