Carbon quantum dot tailored calcium alginate hydrogel for pH responsive controlled delivery of vancomycin

Edible coating using carbon quantum dots for fresh produce preservation: A review of safety perspectives

Fresh produce deteriorates and spoils after harvest due to its perishable nature. Deterioration in quality over time has become a major problem for the food industry, placing an undue burden on the economy and agriculture. Food scientists have developed various methods and technologies to prevent spoilage of fruits and vegetables during storage and logistics. Utilizing carbon quantum dots (CQDs) in the form of active packaging and coatings has been a popular strategy recently. CQDs have recently attracted attention as sustainable and functional nanomaterials. CQDs are popular among food scientists due to their easy and economical synthesis, sustainability, non-toxicity, biocompatibility, edibility, UV protection, and antibacterial and antioxidant activities. Although many studies have been conducted and reviewed on the utilization of CQDs in the manufacture of flexible active packaging materials, relatively few studies have investigated the use of CQDs in edible coating formulations for fresh produce. The main reasons for this are concerns about the potential toxicity and edibility of CQDs if they are coated directly on fresh produce. Therefore, this review aims to address these issues by investigating the dose-dependent non-toxicity and biocompatibility of sustainable CQDs along with other important properties from a food packaging perspective. Additionally, this review focuses on the studies performed so far on the direct coating of CQD-based formulations on fresh and fresh-cut fruits and vegetables and discusses the important impact of CQDs on the quality of coated agricultural products. This review is intended to provide food packaging researchers with confidence and prospects for utilizing sustainable CQDs in direct coating formulations for food.

Synthesis and drug release kinetics of ciprofloxacin from polyacrylamide/dextran/carbon quantum dots (PAM/Dex/CQD) hydrogels

Sustainable release of drug by utilizing β-cyclodextrin (β-CD) based inclusion complex (IC) is the prime objective of the present work. Herein, polyacrylamide/dextran containing carbon quantum dots (PAM/Dex/CQD) nanocomposite hydrogels are prepared by in situ polymerization of acrylamide. The incorporation of CQD triggers the change in orientation of the PAM/Dex polymeric chains to result the formation of stacked surface morphology of the hydrogel. The average particle size of CQD is found to be 4.13 nm from HRTEM analysis. As-synthesized nanocomposite hydrogel exhibits an optimum swelling ratio of 863 % in aqueous medium. The cytotoxicity study is conducted on HeLa cells by taking up to 2 μM concentration of the prepared nanocomposite hydrogel demonstrate 78 % cell viability. In present study, ciprofloxacin (Cipro) is taken as model drug that achieves release of 64.15 % in 32 h from β-Cipro@PAM/Dex/CQD hydrogels in acidic medium. From theoretical study, release rate constants, R2, Akaike information criterion (AIC) and model selection criterion (MSC) are computed to determine the best fitted kinetics model. Peppas-Sahlin model is the best fitted kinetics model for β-Cipro@PAM/Dex/CQD and concluded that the release of Cipro follows Fickian drug diffusion mechanism in acidic medium.

Biomass-derived carbon dots as significant biological tools in the medicinal field: A review

Early disease detection is crucial since it raises the likelihood of treatment and considerably lowers the cost of therapy. Therefore, the improvement of human life and health depends on the development of quick, efficient, and credible biosensing methods. For improving the quality of biosensors, distinct nanostructures have been investigated; among these, carbon dots have gained much interest because of their great performance. Carbon dots, the essential component of fluorescence nanoparticles, having outstanding chemical characteristics, superb biocompatibility, chemical inertness, low toxicity and potential optical characteristics have attracted the researchers from every corner of the globe. Several carbon dots applications have been thoroughly investigated in recent decade, from optoelectronics to biomedical investigations. This review study primarily emphasizes the recent advancements in the field of biomass-derived carbon dots-based drug delivery, gene delivery and bioimaging, and highlights achievements in two major areas: in vivo applications that involve carbon dots absorption in zebrafish and mice, tumour therapeutics, and imaging-guided drug delivery. Additionally, the possible advantages, difficulties, and future possibilities of using carbon dots for biological applications are also explored.

Microwave-assisted synthesis, characterization and in vitro biomedical applications of Hibiscus rosa-sinensis Linn.-mediated carbon quantum dots

In recent years, carbon quantum dots (CQDs) have garnered considerable attention as a promising material for biomedical applications because of their unique optical and biological properties. In this study, CQDs were derived from the leaves of Hibiscus rosa-sinensis Linn. via microwave-assisted technique and characterized using different techniques such as ultraviolet-visible, Fourier transform infrared, fluorescence spectrometry, X-ray diffraction, dynamic light scattering, transmission electron microscopy and energy-dispersive X-ray spectroscopy. Subsequently, their potential for biomedical applications was investigated through in vitro assays assessing scratch healing, anti-inflammatory, antibacterial, and cytotoxicity properties. It was found that the CQDs were fluorescent, polycrystalline, quasi-spherical, ~ 12 nm in size with presence of -OH and -COOH groups on their negatively charged surfaces, and demonstrated good anti-inflammatory by inhibiting protein denaturation, cyclooxygenase-2 and regulating inflammatory cytokines. The CQDs also exhibited antimicrobial activity against Klebsiella pneumoniae and Bacillus cereus, good biocompatibility, along with excellent promotion of cell proliferation in vitro, indicating their potential as a anti-inflammatory and wound healing material. The properties were more enhanced than their precursor, H. rosa-sinensis leaf extract. Hence, the CQDs synthesized from the leaves of H. rosa-sinensis can serve as a potential biomedical agent.

Route-dependent tailoring of carbon dot release in alginate hydrogel beads (HB-Alg@WTR-CDs): A versatile platform for biomedical applications

The present investigation explores the different pathways for development of waste tea residue carbon dots (WTR-CDs) loading into hydrogel matrix for WTR-CDs releasing probe. Fluorescent WTR-CDs incorporated into hydrogel matrix were synthesized by valorisation of kitchen waste tea by simple carbonization method (λem = 450 nm, ΦWTR-CDs =18.45 %). Biopolymeric alginate-based hydrogel beads (HB-Alg) were prepared by simple extrusion method. Three routes (ex-situ/in-situ) were employed for loading of WTR-CDs into hydrogel matrix. Successful synthesis of WTR-CDs and its loading into hydrogel matrix was confirmed via various characterization techniques. Developed protocol was employed for stimuli-responsive cumulative release of WTR-CDs study (pH = 3.0, 7.4, 9.0) was monitored over 7 days. Results suggests that, the HB-Alg@WTR-CDs-A system with in-situ loaded WTR-CDs have sustained release due to ionic interaction of WTR-CDs with crosslinked polymer network, whereas in HB-Alg@WTR-CDs-B, WTR-CDs loaded in wet-beads having burst release in which loosely bound WTR-CDs into hydrogel cavities releases rapidly. While, in case of HB-Alg@WTR-CDs-C, lowest release was observed due to weakly surface bound WTR-CDs, low loading and shrinkage of pores into dry-beads. Radical scavenging activity was studied and shown antioxidant properties of WTR-Powder, WTR-CDs and HB-Alg@WTR-CDs-A,B,C. Cytotoxicity of all systems was checked via CAM assay and significant growth in blood vascularization with no loss of chick embryo confirming the released WTR-CDs are biocompatible. Successful investigation and summarization of results ensure that, waste-valorisation, simple, sustainable, and smart hydrogel systems with different routes of WTR-CDs loading have opened a window to understand the mechanistic pathways in release behaviour. This robust approach for improvement of smarter and biocompatible materials can be fruitfully applicable in advanced, controlled and stimuli responsive delivery probes.

Turning food waste into value-added carbon dots for sustainable food packaging application: A review

Carbon dots (CDs) are a recent addition to the nanocarbon family, encompassing both crystalline and amorphous phases. They have sparked significant research interest due to their unique electrical and optical properties, remarkable biocompatibility, outstanding mechanical characteristics, customizable surface chemistry, and negligible cytotoxicity. Their current applications are mainly limited to flexible photonic and biomedical devices, but they have also garnered attention for their potential use in intelligent packaging. The conversion of food waste into CDs further contributes to the concept of the circular economy. It provides a comprehensive overview of emerging green technologies, energy-saving reactions, and cost-effective starting materials involved in the synthesis of CDs. It also highlights the unique properties of biomass-derived CDs, focusing on their structural performance, cellular toxicity, and functional characteristics. The application of CDs in the food industry, including food packaging, is summarized in a concise manner. This paper sheds light on the current challenges and prospects of utilizing CDs in the packaging industry. It aims to provide researchers with a roadmap to tailor the properties of CDs to suit specific applications in the food industry, particularly in food packaging.

Green Synthesis for Carbon Quantum Dots via Opuntia ficus-indica and Agave maximiliana: Surface-Enhanced Raman Scattering Sensing Applications

In this study, we present an alternative method for synthesizing carbon quantum dots (CQDs) using a green synthesis approach via extracts from Agave maximiliana and Opuntia ficus-indica(Ofi). The extracts from both plants were used as the carbon source for the CQDs. The synthesis method employs mesoporous zeolite 4A as a refractory for the thermal treatment of the samples. Transmission electron microscopy analysis established that the size of the CQDs shows a narrow distribution centered around 2 nm with a maximum size of less than 3 nm for both cases. The CQDs exhibit absorption bands associated with π-π* transitions located around 220 nm. In both cases, photoluminescence (PL) phenomenon was detected by irradiating the samples with a UV wavelength and detecting emissions close to the blue wavelength. Additionally, both kinds of CQDs were tested as surface-enhanced Raman scattering (SERS) substrates against methylene blue (MB), indicating an enhancement associated with ring deformation and stretching modes of the v(C-C) and v(C-N) bonds located around 1400 and 1620 cm-1, respectively. Complementarily, in the framework of density functional theory, H2nC2(2m+1) structures (with n = 3-5 and m = 1-3) were used as a theoretical representation of CQDs in interaction with the MB molecule. It is used for developing the analysis of charge transfer effects between both systems and for specifying elements that generate the SERS effect associated with the chemical enhancement mechanism.

Aptamer-functionalized quantum dots as theranostic nanotools against cancer and bacterial infections: A comprehensive overview of recent trends

Aptamers (Apts) are synthetic nucleic acid ligands that can be engineered to target various molecules, including amino acids, proteins, and pharmaceuticals. Through a series of adsorption, recovery, and amplification steps, Apts are extracted from combinatorial libraries of synthesized nucleic acids. Using aptasensors in bioanalysis and biomedicine can be improved by combining them with nanomaterials. Moreover, Apt-associated nanomaterials, including liposomes, polymeric, dendrimers, carbon nanomaterials, silica, nanorods, magnetic NPs, and quantum dots (QDs), have been widely used as promising nanotools in biomedicine. Following surface modifications and conjugation with appropriate functional groups, these nanomaterials can be successfully used in aptasensing. Advanced biological assays can use Apts immobilized on QD surfaces through physical interaction and chemical bonding. Accordingly, modern QD aptasensing platforms rely on interactions between QDs, Apts, and targets to detect them. QD-Apt conjugates can be used to directly detect prostate, ovarian, colorectal, and lung cancers or simultaneously detect biomarkers associated with these malignancies. Tenascin-C, mucin 1, prostate-specific antigen, prostate-specific membrane antigen, nucleolin, growth factors, and exosomes are among the cancer biomarkers that can be sensitively detected using such bioconjugates. Furthermore, Apt-conjugated QDs have shown great potential for controlling bacterial infections such as Bacillus thuringiensis, Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Campylobacter jejuni, Staphylococcus aureus, and Salmonella typhimurium. This comprehensive review discusses recent advancements in the design of QD-Apt bioconjugates and their applications in cancer and bacterial theranostics.

Antibacterial Carbon Dots: Mechanisms, Design, and Applications

The increase in antibiotic resistance promotes the situation of developing new antibiotics at the forefront, while the development of non-antibiotic pharmaceuticals is equally significant. In the post-antibiotic era, nanomaterials with high antibacterial efficiency and no drug resistance make them attractive candidates for antibacterial materials. Carbon dots (CDs), as a kind of carbon-based zero-dimensional nanomaterial, are attracting much attention for their multifunctional properties. The abundant surface states, tunable photoexcited states, and excellent photo-electron transfer properties make sterilization of CDs feasible and are gradually emerging in the antibacterial field. This review provides comprehensive insights into the recent development of CDs in the antibacterial field. The topics include mechanisms, design, and optimization processes, and their potential practical applications are also highlighted, such as treatment of bacterial infections, against bacterial biofilms, antibacterial surfaces, food preservation, and bacteria imaging and detection. Meanwhile, the challenges and outlook of CDs in the antibacterial field are discussed and proposed.

Fluorescence intensity and fluorescence lifetime measurements of various carbon dots as a function of pH

Measurement and monitoring of pH are essential in both the industry and academia. It is therefore important to continue developing novel, low-cost pH sensors that provide increased accuracy over long periods of time. Particularly promising are sensors based on materials that show pH-dependent fluorescence intensity (FI) and lifetime (FL). Carbon dots (CDs) are emerging as promising candidates because of their low cost, ease of manufacturing, low toxicity, and negligible photobleaching. However, little has been done to quantify the FI and FL values of CDs. Here we report the characterisation of the pH-dependent FI and FL of four novel solvothermal synthesised CDs. The fifth CD is used as a reference sample and was synthesised following a published synthesis. The precursors for the CDs include disperse blue 1 dye, phloroglucinol, m-phenylenediamine (m-PD), N, and N-dimethylformamide (DMF). The average diameter size of the CDs ranges from 1.5 to 15 nm. An excitation wavelength of 452 nm with a bandwidth of 45 nm was used to quantify the fluorescence in the pH range 5-9. Three CDs show a decreasing trend in FI with pH, while two CDs show an increasing trend. None of the CDs shows strong FL dependence. The FL changes around 0.5 ± 0.2 ns across the tested pH range. We suggest that the differences in the fluorescence trends can be attributed to the precursors chosen for synthesising the CDs.

Curcumin-loaded Butea monosperma gum-based hydrogel: A new excipient for controlled drug delivery and anti-bacterial applications

The wide spectrum of applications provided by curcumin has attracted researchers worldwide to identify its molecular targets and employ it in various biomedical applications. The present research work focuses on the development of a Butea monosperma gum-based hydrogel encapsulated with curcumin and further employing it for two diverse applications, i.e., drug delivery and anti-bacterial application. A central composite design was utilized for the optimization of significant process variables to achieve maximum swelling. A maximum of 662 % swelling was attained at the initiator (0.06 g), monomer (3 ml), crosslinker (0.08 g), solvent (14 ml), and time (60 s). Furthermore, the characterization of the synthesized hydrogel was performed via FTIR, SEM, TGA, H1-NMR, and XRD analysis. Various important properties like swelling rate under different solutions, water retention capacity, re-swelling capability, porosity, and density measurement suggested that the prepared hydrogel exhibited a highly stable crosslinked network with high porosity (0.23) and density (62.5 g/cm³) values. The encapsulation efficiency of curcumin in the hydrogel was reported to be 93 % and 87.3 %, respectively, wherein BM-g-poly(AA) ~ Cur exhibited excellent sustained pH-responsive site release of curcumin at two different pH values, with the maximum amount of release taking place at pH 7.4 (792 ppm) and a minimum at pH 5 (550 ppm) due to the lesser ionization of the functional groups present in the hydrogel at a lower pH value. Additionally, the results from the pH shock studies indicated our material to be stable and efficient even with fluctuations in pH, resulting in the optimal amount of drug release at each pH range. Furthermore, anti-bacterial studies revealed that the synthesized BM-g-poly(AA) ~ Cur was effective against both gram-negative and gram-positive bacteria, with maximum values of zones of inhibition of 16 mm in diameter, thereby showing the best results in comparison to the already developed matrices to date. As a result, the newly discovered BM-g-poly(AA) ~ Cur properties reflect the hydrogel network's suitability for drug release and anti-bacterial applications.

Host-guest drug delivery by β-cyclodextrin assisted polysaccharide vehicles: A review

Among different form of cyclodextrin (CD), β-CD has been taken a special attraction in pharmaceutical science due to lowest aqueous solubility and adequate cavity size. When β-CD forms inclusion complex with drugs then biopolymers such as polysaccharides in combination plays a vital role as a vehicle for safe release of drugs. It is noticed that, β-CD assisted polysaccharide-based composite achieves better drug release rate through host-guest mechanism. Present review is a critical analysis of this host-guest mechanism for release of drugs from polysaccharide supported β-CD inclusion complex. Various important polysaccharides such as cellulose, alginate, chitosan, dextran, etc. in relevant to drug delivery are logically compared in present review by their association with β-CD. Efficacy of mechanism of drug delivery by different polysaccharides with β-CD is analytically examined in schematic form. Drug release capacity at different pH conditions, mode of drug release, along with characterization techniques adopted by individual polysaccharide-based CD complexes are comparatively established in tabular form. This review may explore better visibility for researchers those are working in the area of controlled release of drugs by vehicle consist of β-CD associated polysaccharide composite through host-guest mechanism.

Cyclodextrin regulated natural polysaccharide hydrogels for biomedical applications-a review

Cyclodextrin and its derivative (CDs) are natural building blocks for linking with other components to afford functional biomaterials. Hydrogels are polymer network systems that can form hydrophilic three-dimensional network structures through different cross-linking methods and are developing as potential materials in biomedical applications. Natural polysaccharide hydrogels (NPHs) are widely adopted in biomedical field with good biocompatibility, biodegradability, low cytotoxicity, and versatility in emulating natural tissue properties. Compared with conventional NPHs, CD regulated natural polysaccharide hydrogels (CD-NPHs) maintain good biocompatibility, while improving poor mechanical qualities and unpredictable gelation times. Recently, there has been increasing and considerable usage of CD-NPHs while there is still no review comprehensively introducing their construction, classification, and application of these hydrogels from the material point of view regarding biomedical fields. To draw a complete picture of the current and future development of CD-NPHs, we systematically overview the classification of CD-NPHs, and provide a holistic view on the role of CD-NPHs in different biomedical fields, especially in drug delivery, wound dressing, cell encapsulation, and tissue engineering. Moreover, the current challenges and prospects of CD-NPHs are discussed rationally, providing an insight into developing vibrant fields of CD-NPHs-based biomedicine, and facilitating their translation from bench to clinical medicine.

Fabrication and investigating in vivo wound healing property of coconut oil loaded nanofiber/hydrogel hybrid scaffold

Obtaining a sustainable drug delivery system is a challenging issue in biomedical science. This became even more important in the wound regeneration process due to its long treatment process. In this study, the calcium alginate (CaAlg) hydrogel is coated on the surface of polycaprolactone (PCL)/gelatin (Gel) nanofibers containing coconut oil (CO) using the impregnation method. The physical, chemical, and morphological properties of produced samples are investigated using different characterization techniques to verify the influence of hydrogel. Water contact angle, swelling ratio, and water vapor permeability measurements are used to evaluate the effect of hydrogel on the hydrophilicity of the proposed system. The cell viability test showed that the nanocomposite hydrogel is biocompatible and could improve wound healing. According to drug release studies, hydrogel addition to the nanofiber system plays an essential role in controlling CO release rate in the first 250 h. In vivo studies also indicated faster skin regeneration.

A Hydrothermal Method to Generate Carbon Quantum Dots from Waste Bones and Their Detection of Laundry Powder

Surfactants are one of the major pollutants in laundry powder, which have an impact on the environment and human health. Carbon quantum dots (CQDs) are spherical zero-dimensional fluorescent nanoparticles with great potential for fluorescent probing, electrochemical biosensing and ion sensing. Herein, a bottom-up approach was developed for the synthesis of CQDs from biomass to detect laundry detergent and laundry powder. Waste chicken bones were used as carbon precursors after being dried, crushed and reacted with pure water at 180 °C for 4 h to generate CQDs, which exhibited a monodisperse quasi-spherical structure with an average particle size of 3.2 ± 0.2 nm. Functional groups, including -OH, C=O, C=C and C-O, were identified on the surface of the prepared CQDs. The optimal fluorescence excitation wavelength of the yellow-brown CQDs was 380 nm, with a corresponding emission peak at 465 nm. CQDs did not significantly increase cell death in multiple cell lines at concentrations of 200 µg·mL⁻¹. Fluorescence enhancement of CQDs was observed after addition of sodium dodecyl benzene sulphonate, a major anionic surfactant in laundry powder. A linear relationship between fluorescence enhancement CQDs and the concentration of laundry powder was established. Thus, a hydrothermal method was developed to generate CQDs from waste biomass that may be used as a fluorescent probe to detect laundry powder.

What makes carbon nanoparticle a potent material for biological application?

Carbon materials are generally utilized in the form of carbon allotropes and their characteristics are exploited as such or for improving the thermal, electrical, optical, and mechanical properties of other biomaterials. This has now found a broader share in conventional biomaterial space with the generation of nanodiamond, carbon dot, carbon nanoparticles (CNPs), and so forth. With properties of better biocompatibility, intrinsic optical emission, aqueous suspendability, and easier surface conjugation possibilities made CNPs as one of the fore most choice for biological applications especially for use in intracellular spaces. There are various reports available presenting methods of preparing, characterizing, and using CNPs for various biological applications but a collection of information on what makes CNP a suitable biomaterial to achieve those biological activities is yet to be provided in a significant way. Herein, a series of correlations among synthesis, characterization, and mode of utilization of CNP have been incorporated along with the variations in its use as agent for sensing, imaging, and therapy of different diseases or conditions. It is ensembled that how simplified and optimized methods of synthesis is correlated with specific characteristics of CNPs which were found to be suitable in the specific biological applications. These comparisons and correlations among various CNPs, will surely provide a platform to generate new edition of this nanomaterial with improvised applications and newer methods of evaluating structural, physical, and functional properties. This may ensure the eventual use of CNPs for human being for specific need in near future. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing Diagnostic Tools > In Vitro Nanoparticle-Based Sensing Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Nanoantibiotics to fight multidrug resistant infections by Gram-positive bacteria: hope or reality?

The spread of antimicrobial resistance in Gram-positive pathogens represents a threat to human health. To counteract the current lack of novel antibiotics, alternative antibacterial treatments have been increasingly investigated. This review covers the last decade's developments in using nanoparticles as carriers for the two classes of frontline antibiotics active on multidrug-resistant Gram-positive pathogens, i.e., glycopeptide antibiotics and daptomycin. Most of the reviewed papers deal with vancomycin nanoformulations, being teicoplanin- and daptomycin-carrying nanosystems much less investigated. Special attention is addressed to nanoantibiotics used for contrasting biofilm-associated infections. The status of the art related to nanoantibiotic toxicity is critically reviewed.

Surface molecularly imprinted solid-phase extraction for the determination of vancomycin and norvancomycin in milk by liquid chromatography coupled to tandem mass spectrometry

A simple and sensitive method based on surface molecularly imprinted solid-phase extraction (SMISPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to determine the residues of vancomycin (VCM) and norvancomycin (NVCM) in milk samples. The imprinted polymer prepared with teicoplanin as a virtual template can specifically recognize VCM and NVCM. The samples were purified with SMISPE and analyzed by LC-MS/MS in positive ionization mode. The results showed that the VCM and NVCM had a good linear correlation in the range of 0.5 μg/kg to 50 μg/kg. The recoveries of target analytes were from 83.3% to 92.1%, and the limits of quantification were both 1.0 μg/kg. The matrix effects of VCM and NVCM were -11.0% and -3.43%, respectively. The proposed method can efficiently eliminate the interference from matrix compounds and reduce baseline noise, which is useful for the monitoring of the residues of VCM and NVCM in milk samples.

A sustainable green synthesis of functionalized biocompatible carbon quantum dots from Aloe barbadensis Miller and its multifunctional applications

Herein, we demonstrated a sustainable green approach for the preparation of fluorescent biocompatible carbon quantum dots by microwave-assisted reflux synthesis from Aloe barbadensis Miller (Aloe vera) extract. The Transmission Electron Microscopic images reveal that the as-prepared CQDs are spherical with less than 5 nm in size. The CQDs are amorphous, showed an excitation-independent behaviour, emitted blue fluorescence and have a fluorescence quantum yield of 31%. The presence of -OH groups contributed to the blue emission and helped CQDs to disperse uniformly in an aqueous solution. The prepared CQDs were employed as a photocatalyst for the environmental remediation to degrade the anionic dye, eosin yellow under visible light irradiation. The results showed that the CQDs exhibited excellent photocatalytic efficiency of 98.55% within 80 min and a 100% efficiency within 100 min. Further, the cytotoxic properties of as-prepared CQDs are investigated in the MCF-7 breast cancer cell line using MTT assay. The results demonstrated a notable reduction in cell viability in a dose-subjected manner, and the cell viability decreased to 50% (IC₅₀) at a concentration of 52.2 ± 1.35 μg/mL. Furthermore, cellular internalization of CQDs in breast cancer cells is studied. As expected, CQDs are found to internalize by the cancer cells with blue emission as revealed by fluorescence microscope. In the end, CQDs in human breast cancer cells demonstrate the anti-proliferative effect and are found to be an impressive fluorescent probe for live-cell imaging, paving a path for its potential biomedical applications.

Facile synthesis of a carbon dots and silver nanoparticles (CDs/AgNPs) composite for antibacterial application

Bacterial infections can seriously harm human health, and the overuse of traditional antibiotics and antibacterial agents will increase the resistance of bacteria. Therefore, it is necessary to prepare a new kind of antibacterial material. In this work, a carbon dots and silver nanoparticles (CDs/AgNPs) composite has been synthesized in a one-step facile method without the introduction of toxic chemicals, wherein CDs could serve as a reducing and stabilizing agent. The CDs/AgNPs composite was characterized by UV-vis spectrophotometry, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM), which demonstrate that the silver nanoparticles were successfully synthesized in the composite. The zeta potential of the CDs/AgNPs composite was −15.3 mV, indicating that the composite possesses high stability. Furthermore, the composite also exhibited biocidal effects for both Gram-negative E. coli bacteria and Gram-positive S. aureus bacteria. Thus, the composite is considered to be of great potential in bactericidal and biomedical applications.

One-step facile synthesis of a carbon dots and silver nanoparticles (CDs/AgNPs) composite without the introduction of toxic chemicals.

Facile Hydrothermal and Solvothermal Synthesis and Characterization of Nitrogen-Doped Carbon Dots from Palm Kernel Shell Precursor

Carbon dots (CDs), a nanomaterial synthesized from organic precursors rich in carbon content with excellent fluorescent property, are in high demand for many purposes, including sensing and biosensing applications. This research focused on preparing CDs from natural and abundant waste, palm kernel shells (PKS) obtained from palm oil biomass, aiming for sensing and biosensing applications. Ethylenediamine and L-phenylalanine doped CDs were produced via the hydrothermal and solvothermal methods using one-pot synthesis techniques in an autoclave batch reactor. The as-prepared N-CDs shows excellent photoluminescence (PL) property and a quantum yield (QY) of 13.7% for ethylenediamine (EDA) doped N-CDs (CDs-EDA) and 8.6% for L-phenylalanine (L-Ph) doped N-CDs (CDs-LPh) with an excitation/emission wavelength of 360 nm/450 nm. The transmission electron microscopy (TEM) images show the N-CDs have an average particle size of 2 nm for both CDs. UV-Visible spectrophotometric results showed C=C and C=O transition. FTIR results show and confirm the presence of functional groups, such as -OH, -C=O, -NH2 on the N-CDs, and the X-ray diffraction pattern showed that the N-CDs were crystalline, depicted with sharp peaks. This research work demonstrated that palm kernel shell biomass often thrown away as waste can produce CDs with excellent physicochemical properties.

Carbon dots: A novel trend in pharmaceutical applications

Carbon quantum dots (CQDs, C-dots, or CDs), are generally small carbon nanoparticles having a size less than 10nm. Carbon dots (CDs) were accidentally discovered during the purification of single-walled carbon nanotubes through preparative electrophoresis in 2004. Carbon is an organic material having poor water solubility that emits less fluorescence. However, CDs have good aqueous solubility and excellent fluorescent property, hence more attention has been given to the synthesis of CDs and their applications in chemistry and allied sciences. CDs being easily accessible for in-house synthesis, simpler fabrication as per compendial requirements are wisely accepted. In addition, since CDs are biocompatible, of low toxicity, and of biodegradable nature, they appear as a promising tool for the health care sector. Furthermore, owing to their capabilities of expressing significant interaction with biological materials, and their excellent photoluminescence (PL), CDs have been emerging as novel pioneered nanoparticles useful for pharmaceutical and theranostic applications. Also, CDs are more eco-friendly in synthesis and therefore can be favorably consumed as alternatives in the further development of biological, environmental, and food areas. A massive study has been performed dealing with different approaches which are adopted for CDs synthesis and their applications as, filters for the separation of pollutants from polluted water, food safety, toxicological studies, and optical properties, etc. While still less emphasis is given on the applications of CDs in pharmaceuticals like for sustained and targeted drug delivery systems, theranostic study, etc. Hence, in the present review, we are exploring CQDs as a boon to pharmaceutical concerns.

Chitosan/carbon quantum dot/aptamer complex as a potential anticancer drug delivery system towards the release of 5-fluorouracil

Nowadays, nanotechnology contributes diminishing side effects rather than traditional therapeutic methods like chemotherapy. Thus, designing a biocompatible specific targeted nanocarrier with prolonged half-life and enhanced bio-availability using simultaneous cell imaging seems urgent. To meet this demand, 5-fluorouracil-chitosan‑carbon quantum dot-aptamer (5-FU-CS-CQD-Apt) nanoparticle was successfully synthesized for specific targeted delivery of 5-FU anti-cancer drug used in breast cancer treatment and this was done by following facile water-in-oil (W/O) emulsification method. Physicochemical properties were characterized and high drug loading and entrapment efficiency were achieved. The average size and zeta potential of the nanoparticle were 122.7 nm and + 31.2 mV, respectively. According to the in-vitro drug release profile, 5-FU-CS-CQD-Apt released the drug in a controlled manner. MTT assay, flow cytometry, fluorescence microscopy, and gene expression results demonstrated that the blank nanoparticle was biocompatible, and 5-FU-CS-CQD-Apt could kill tumor cells efficiently. Bcl-2/Bax ratio was decreased after 5-FU-CS-CQD-Apt treatment in MCF-7 cells. It was concluded that 5-FU-CS-CQD-Apt could be used as a potential nanocarrier in breast cancer treatment.

Current Status of Vancomycin Analytical Methods

BACKGROUND

The glycopeptide antibiotics are a class of antimicrobial drugs that are an important alternative for cases of bacterial infections resistant to penicillins, besides being able to be used to treat infections in people allergic to pencilin. They have great activity against Gram-positive microorganisms, including methicillin-resistant Staphylococcus aureus (MRSA), by inhibiting the cell wall synthesis.

OBJECTIVE

There are many analytical methods in the literature for determination of antimicrobial glycopeptide vancomycin in different matrixes that are very effective; however, all of them use toxic solvents, contributing to the generation of waste, causing damage to the environment and to the operator, as well as increased costs of analysis.

RESULTS

The most prevailing method found was high performance liquid chromatography (HPLC), followed by microbiological assays and, in less quantity, spectrometric methods. The chromatographic methods use organic solvents that are toxic, such as acetonitrile and methanol, and buffer solutions, that can damage the equipment and the column. In the microbiological assays the disc diffusion methods are still in the majority. The spectrophotometric methods were based in the UV-Vis region using buffer solutions as a diluent.

CONCLUSIONS

All these methods can become greener, following green analytical chemistry principles, which could bring benefits both to the environment and the operator, and reduce costs.

HIGHLIGHTS

In this paper, a literature review regarding analytical methods for determination of vancomycin was carried out with a suggestion of greener alternatives.

Rifampicin loaded in alginate/chitosan nanoparticles as a promising pulmonary carrier against Staphylococcus aureus

This study aims to explore the antimicrobial activity of rifampicin (RIF) and ascorbic acid (ASC) co-loaded into alginate (ALG)/chitosan (CS) nanoparticles (RIF/ASC NPs) and tested for their antibacterial activity against several strains of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA). Also, the present research focused on exploring the possible antibacterial mechanism of action of these RIF/ASC NPs, which demonstrated a significant biocide activity against the S. aureus strains with minimum inhibitory concentrations (MIC) between 2- and 8-fold lower than those one exhibited with the free antibiotic RIF. The proposed antimicrobial mechanism of action of the RIF/ASC NPs seems to be the result of collaborative effects between NPs and the RIF/ASC antibiotic combination. Moreover, results indicated that the functionalized RIF/ASC NP surface played a crucial role on the processes of NP adhesion into the bacterial surface, the alterations on the cell membrane integrity, and the cell uptake of the RIF/ASC antibiotic into bacteria. Further, the in vivo lung deposition pattern of empty NPs labeled (NPs-FITC) with isothiocyanate fluorescein in rats was investigated post intratracheal instillation of NPs. In summary, findings from this work show that our novel designed engineered RIF/ASC co-loaded NPs could be a suitable system for antibiotic lung administration with promising perspectives for effective treatments of pulmonary intracellular infections for those known antibiotics that are losing effectiveness due to antimicrobial resistance problems. Graphical Abstract.

Carbon dots with pH-responsive fluorescence: a review on synthesis and cell biological applications

This review summarizes state of the art synthesis and applications of carbon dots (CDs) with pH-responsive fluorescence. Following an introduction, the first section covers methods for the preparation of pH-responsive CDs, with subsections on general methods for preparing CDs (by hydrothermal, solvothermal, electrochemical, microwave, laser ablation, pyrolysis or chemical oxidation polymerization methods), and on precursors for synthesis. This is followed by a section on the mechanisms of pH-responsivity (by creating new functional groups, change of energy levels, protonation and deprotonation, aggregation, or by introduction shells). Several Tables are presented that give an overview of the wealth of methods and materials. A final section covers applications of carbon dots (CDs) with pH-responsive fluorescence for sensing, drug delivery, and imaging. The conclusion summarizes the current status, addresses challenges, and gives an outlook on potential future trends. Graphical abstract The synthesis and biological applications of carbon dots(CDs) with pH-responsive fluorescence are summarized. Precursors and methods for preparation of pH-responsive CDs, mechanisms of pH-responsivity, and biological applications of CDs with pH-responsive fluorescence for sensing, drug delivery, and imaging are discussed.

Multifaceted applications of green carbon dots synthesized from renewable sources

Fluorescent carbon dots (CDs) are an emerging class of nanomaterials in the carbon family. There are various inexpensive and renewable resources that can be used to synthesize green CDs, which have received immense attention from researchers because of their improved aqueous solubility, high biocompatibility, and eco-friendly nature compared with chemically derived CDs. Additional surface passivation is not required, as heteroatoms are present on the surface of green CDs in the form of amine, hydroxyl, carboxyl, or thiol functional groups, which can improve their physicochemical properties, quantum yield, and the probability of visible light absorption. Green CDs have potential applications in the fields of bioimaging, drug/gene delivery systems, catalysis, and sensing. Since their discovery, there have been several review articles that describe the synthesis of green CDs and some of their applications. However, there are no review articles describing the synthesis and complete applications of green CDs. Here, we provide detailed information regarding their synthesis and applications based on the available literature. In addition, we discuss some of the less explored applications of green CDs and the challenges that remain to be overcome.

Theranostic applications of stimulus-responsive systems based on carbon dots

Over recent years, many different nanoparticle-based drug delivery systems (NDDSs) have been developed. Recently the development of stimulus-responsive NDDSs has come into sharper focus. Carbon dots (CDs) possess outstanding features such as useful optical properties, good biocompatibility, and the ability for easy surface modification. Appropriate surface modification can allow these NDDSs to respond to various chemical or physical stimuli that are characteristic of their target cells or tissue (frequently malignant cells or tumors). The present review covers recent developments of CDs in NDDSs with a particular focus on internal stimulus response capability that allows simultaneous imaging and therapeutic delivery (theranostics). Relevant stimuli associated with tumor cells and tumors include pH levels, redox potential, and different enzymatic activities can be used to activate the CDs at the desired sites.

Cancer Therapy Based on Smart Drug Delivery with Advanced Nanoparticles

Background:

Cancer, as one of the most dangerous disease, causes millions of deaths every year. The main reason is the absence of an effective and thorough treatment. Drug delivery systems have significantly reduced the side-effect of chemotherapy. Combined with nanotechnology, smart drug delivery systems including many different nanoparticles can reduce the side-effect of chemotherapy better than traditional drug delivery systems.

Methods:

In this article, we will describe in detail the different kinds of nanoparticles and their mechanisms emphasizing the triggering factors in drug delivery. Besides, the application of smart drug delivery systems in imaging will be introduced.

Results:

Combined with nanotechnology, smart drug delivery systems including many different nanoparticles can reduce the side-effect of chemotherapy better than traditional drug delivery systems.

Conclusion:

Despite considerable progress in nanoparticle research over the past decade, such as smart drug delivery systems for the treatment of cancer, molecular imaging probes and the like. The range of nanoparticles used in multifunction systems for imaging and drug delivery continues to grow and we expect this dilatation to continue. But to make nanoparticles truly a series of clinical products to complement and replace current tools, constant exploration efforts and time are required. Overall, the future looks really bright.

Green Nanotechnology-Driven Drug Delivery Assemblies

Green nanotechnology incorporates the principles of green chemistry and green engineering to fabricate innocuous and eco-friendly nanoassemblies to combat the problems affecting the human health or environment. Subsequently, amalgamation of green nanotechnology with drug delivery area has actually commenced a new realm of "green nanomedicine". The burgeoning demand for green nanotechnology-driven drug delivery systems has led to the development of different types of delivery devices, like inorganic (metallic) nanoparticles, quantum dots, organic polymeric nanoparticles, mesoporous silica nanoparticles, dendrimers, nanostructured lipid carriers, solid lipid nanoparticles, etc. The present article deals with a brief account of delivery devices produced from green methods and describes site-specific drug delivery systems (including their pros and cons) and their relevance in the field of green nanomedicine.

Carbon quantum dots and their biomedical and therapeutic applications: a review

In recent years, nano carbon quantum dots (CQDs) have received increasing attention due to their properties such as small size, fluorescence emission, chemical stability, water solubility, easy synthesis, and the possibility of functionalization. CQDs are fluorescent 0D carbon nanostructures with sizes below 10 nm. The fluorescence in CQDs originates from two sources, the fluorescence emission from bandgap transitions of conjugated π-domains and fluorescence from surface defects. The CQDs can emit fluorescence in the near-infrared (NIR) spectral region which makes them appropriate for biomedical applications. The fluorescence in these structures can be tuned with respect to the excitation wavelength. The CQDs have found applications in different areas such as biomedicine, photocatalysis, photosensors, solar energy conversion, light emitting diodes (LEDs), etc. The biomedical applications of CQDs include bioimaging, drug delivery, gene delivery, and cancer therapy. The fluorescent CQDs have low toxicity and other exceptional physicochemical properties in comparison to heavy metals semiconductor quantum dots (QDs) which make them superior candidates for biomedical applications. In this review, the synthesis routes and optical properties of the CQDs are clarified and recent advances in CQDs biomedical applications in bioimaging (in vivo and in vitro), drug delivery, cancer therapy, their potential to pass blood-brain barrier (BBB), and gene delivery are discussed.

Carbamazepine removal from water by carbon dot-modified magnetic carbon nanotubes

Carbon dot- and magnetite-modified magnetic carbon nanotubes (CMNTs) were synthesized and evaluated for carbamazepine removal from water. The adsorbent was characterized by multiple modern surface and microstructure analyzing techniques. CMNTs were composed of three components including carbon dots (CDs), carbon nanotubes (CNTs) and magnetite. CDs and CNTs introduce abundant carboxyl groups onto CMNTs and magnetite allows rapid magnetic separation of the adsorbent realizable after batch adsorption. This adsorbent has a moderately high adsorption capacity of 65 mg-carbamazepine/g-adsorbent at pH 7.0 ± 0.2, which is superior to many reported adsorbents. Carbamazepine was uptaken well in a wide pH range, regardless of the surface charging of CMNTs. Its adsorption on CMNTs was quite fast and reached 80% of removal during the initial 3 h. The mass transfer within CMNTs and the time-dependent utilization, exhaustion and depletion of the adsorption capacity were successfully described using a simplified homogeneous surface diffusion model (HSDM). The surface diffusion coefficients (D_s) rose with increasing initial carbamazepine concentrations. After six regeneration and recycle experiments, the capacity loss of CMNTs was less than 2.2% at the conditions tested. FTIR spectra showed the characteristics of the components. Raman spectra implied a π-π electron donor-acceptor (EDA) interaction during adsorption. This work proposed a method of combining π-bond-rich materials (CNTs and CDs) and magnetite to make separable composite adsorbents with high affinity interactions between carbamazepine and carbon materials. The prepared adsorbent is attractive for carbamazepine removal due to its good performance, moderate cost, ease of separation, and ability to regenerate.