Nanomaterials-based advanced systems for photothermal / photodynamic therapy of oral cancer

The traditional clinical approaches for oral cancer consist of surgery, chemotherapy, radiotherapy, immunotherapy, and so on. However, these treatments often induce side effects and exhibit limited efficacy. Photothermal therapy (PTT) emerges as a promising adjuvant treatment, utilizing photothermal agents (PTAs) to convert light energy into heat for tumor ablation. Another innovative approach, photodynamic therapy (PDT), leverages photosensitizers (PSs) and specific wavelength laser irradiation to generate reactive oxygen species (ROS), offering an effective and non-toxic alternative. The relevant combination therapies have been reported in the field of oral cancer. Simultaneously, the advancement of nanomaterials has propelled the clinical application of PTT and PDT. Therefore, a comprehensive understanding of PTT and PDT is required for better application in oral cancer treatment. Here, we review the use of PTT and PDT in oral cancer, including noble metal materials (e.g., Au nanoparticles), carbon materials (e.g., graphene oxide), organic dye molecules (e.g., indocyanine green), organic molecule-based agents (e.g., porphyrin-analog phthalocyanine) and other inorganic materials (e.g., MXenes), exemplify the advantages and disadvantages of common PTAs and PSs, and summarize the combination therapies of PTT with PDT, PTT/PDT with chemotherapy, PTT with radiotherapy, PTT/PDT with immunotherapy, and PTT/PDT with gene therapy in the treatment of oral cancer. The challenges related to the PTT/PDT combination therapy and potential solutions are also discussed.

Carbon Quantum Dots: Properties, Preparation, and Applications

Carbon quantum dots are a novel form of carbon material. They offer numerous benefits including particle size adjustability, light resistance, ease of functionalization, low toxicity, excellent biocompatibility, and high-water solubility, as well as their easy accessibility of raw materials. Carbon quantum dots have been widely used in various fields. The preparation methods employed are predominantly top-down methods such as arc discharge, laser ablation, electrochemical and chemical oxidation, as well as bottom-up methods such as templates, microwave, and hydrothermal techniques. This article provides an overview of the properties, preparation methods, raw materials for preparation, and the heteroatom doping of carbon quantum dots, and it summarizes the applications in related fields, such as optoelectronics, bioimaging, drug delivery, cancer therapy, sensors, and environmental remediation. Finally, currently encountered issues of carbon quantum dots are presented. The latest research progress in synthesis and application, as well as the challenges outlined in this review, can help and encourage future research on carbon quantum dots.

Carbon Dots: Synthesis, Characterizations, and Recent Advancements in Biomedical, Optoelectronics, Sensing, and Catalysis Applications

Carbon nanodots (CNDs), a fascinating carbon-based nanomaterial (typical size 2-10 nm) owing to their superior optical properties, high biocompatibility, and cell penetrability, have tremendous applications in different interdisciplinary fields. Here, in this Review, we first explore the superiority of CNDs over other nanomaterials in the biomedical, optoelectronics, analytical sensing, and photocatalysis domains. Beginning with synthesis, characterization, and purification techniques, we even address fundamental questions surrounding CNDs such as emission origin and excitation-dependent behavior. Then we explore recent advancements in their applications, focusing on biological/biomedical uses like specific organelle bioimaging, drug/gene delivery, biosensing, and photothermal therapy. In optoelectronics, we cover CND-based solar cells, perovskite solar cells, and their role in LEDs and WLEDs. Analytical sensing applications include the detection of metals, hazardous chemicals, and proteins. In catalysis, we examine roles in photocatalysis, CO2 reduction, water splitting, stereospecific synthesis, and pollutant degradation. With this Review, we intend to further spark interest in CNDs and CND-based composites by highlighting their many benefits across a wide range of applications.

Synthesis, characterization and biocompatibility studies of carbon quantum dots from Phoenix dactylifera

In the present study, Carbon Quantum Dots (CQDs) were synthesized from Phoenix dactylifera (Date palm fruit) using microwave-assisted pyrolysis and were characterized for its various properties. The synthesized CQD sample exhibited a narrow absorbance peak at 270 nm in UV-Vis spectrum that indicated generation of narrow sized particles. The FTIR analysis of the crude CQDs and dialysed sample revealed the various functional groups involved in the formation of CQDs. TEM data revealed the nature of CQDs to be quasi-spherical and spatially distributed. Biocompatibility of the CQDs was studied using various model systems. CQDs displayed no cytotoxic and anti-clonogenic property when exposed to WRL-68 cell line whereas a slight toxicity was evident in HT1080 post 24 h of incubation suggesting the tremendous potential of the CQDs in the synergistic killing of cancer cells. Phytotoxicity assessment in four different seedlings revealed the non-toxic nature of CQDs. Further these CQDs were found to possess high biocompatibility imposing no inhibition in microbial growth and zilch effect on the development of zebrafish embryos. Thus these CQDs can find immense potential applications in fields of biomedicine as biomolecule detection, drug carriers, fluorescent tracers and in controlling the drug release.

Recent advances in the modification of carbon-based quantum dots for biomedical applications

Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface functionalization, polymer capping, nano-composite and core-shell structures, and the drawbacks and challenges in each of these methods are discussed.

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.

Evaluation of the dialysis time required for carbon dots by HPLC and the properties of carbon dots after HPLC fractionation

HPLC can be used to evaluate the dialysis time required for C-dots and separate multiple C-dots in solution.

Non-Metal-Heteroatom-Doped Carbon Dots: Synthesis and Properties

Carbon dots (CDs) are new materials with applications in bioimaging, optical devices, catalysis, and many other fields. Their advantages, such as ease of large-scale preparation, low-costing precursors, highly tunable photoluminescence, satisfactory biocompatibility, and photostability against photobleaching, make them competitive alternatives to conventional semiconductor-based quantum dots and organic dyes. To overwhelm other luminescent materials in applications, their functionalities still need to be improved in spite of the abovementioned advantages. In recent years, it has been proven that heteroatom doping is an effective approach to improve the optical and electronic performance of CDs by tuning their carbon skeleton matrices and chemical structures. In this review, the development of non-metal-heteroatom-doped CDs, including heteroatom categories, preparation methods, and physicochemical properties, are discussed. Progressive trends in heteroatom-doped CDs are also discussed at the end of this review.

A rapid microwave synthesis of green-emissive carbon dots with solid-state fluorescence and pH-sensitive properties

The emerging carbon quantum dots (CQDs) have been attracting significant attention for their prominent fluorescence, excellent stability and outstanding biocompatibility. Here, we report a facile one-step synthesis of highly fluorescent CQDs by using phthalic acid and triethylenediamine hexahydrate as precursors through a simple microwave-assisted method. The reaction time needed is only 60 s, which is less time-consuming than most previous reports. The phthalic acid with a benzene ring can improve the photoluminescence properties of CQDs as it can provide foreign sp2 conjugating units, and then finally result in long-wavelength emission. The synthesized CQDs were fully characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Besides, the impacts of different freed ratio on physical and chemical properties of CQDs were investigated in detail. The prepared CQDs exhibited strong green fluorescence with a broad maximum emission wavelength. The quantum yields of the CQDs can reach 16.1% in aqueous solution and they were successfully used in cell imaging with good biocompatibility. Moreover, in solid state, the CQDs with the feed ratio of 1 : 0.5 showed a strong green-yellow fluorescence which may have great potential to fabricate optoelectronic devices. Furthermore, the prepared CQDs also showed high pH sensitivity and can act as a fluorescence nanosensor for pH sensing.

Efficient synthesis of highly fluorescent carbon dots by microreactor method and their application in Fe3+ ion detection

Rapidly obtaining strong photoluminescence (PL) of carbon dots with high stability is crucial in all practical applications of carbon dots, such as cell imaging and biological detection. In this study, we proposed a rapid, continuous carbon dots synthesis technique by using a microreactor method. By taking advantage of the microreactor, we were able to rapidly synthesized CDs at a large scale in less than 5min, and a high quantum yield of 60.1% was achieved. This method is faster and more efficient than most of the previously reported methods. To explore the relationship between the microreactor structure and CDs PL properties, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were carried out. The results show the surface functional groups and element contents influence the PL emission. Subsequent ion detection experiments indicated that CDs are very suitable for use as nanoprobes for Fe³⁺ ion detection, and the lowest detection limit for Fe³⁺ is 0.239μM, which is superior to many other research studies. This rapid and simple synthesis method will not only aid the development of the quantum dots industrialization but also provide a powerful and portable tool for the rapid and continuous online synthesis of quantum dots supporting their application in cell imaging and safety detection.

Cultivating Fluorescent Flowers with Highly Luminescent Carbon Dots Fabricated by a Double Passivation Method

In this work, we present the fabrication of highly luminescent carbon dots (CDs) by a double passivation method with the assistance of Ca(OH)₂. In the reaction process, Ca2+ protects the active functional groups from overconsumption during dehydration and carbonization, and the electron-withdrawing groups on the CD surface are converted to electron-donating groups by the hydroxyl ions. As a result, the fluorescence quantum yield of the CDs was found to increase with increasing Ca(OH)₂ content in the reaction process. A blue-shift optical spectrum of the CDs was also found with increasing Ca(OH)₂ content, which could be attributed to the increasing of the energy gaps for the CDs. The highly photoluminescent CDs obtained (quantum yield: 86%) were used to cultivate fluorescent carnations by a water culture method, while the results of fluorescence microscopy analysis indicated that the CDs had entered the plant tissue structure.