Carbon dots (CDs) have become versatile nanomaterials that have found practical applications in cancer therapy due to their small size, tunable photoluminescence, and high biocompatibility. Modified CDs have shown remarkable potential in targeted drug delivery systems, enhancing solubility and specificity in tumor sites while minimizing systemic toxicity. Gene therapy applications take advantage of the ability of CDs to condense and protect genetic material from degradation, thereby facilitating efficient cellular uptake. Furthermore, metal-doped CDs can function as fluorophores and enhance imaging capabilities for tumor detection through fluorescence and MRI. Besides, in phototherapy applications, when combining photodynamic (PDT) and photothermal therapy (PTT), CDs exhibit synergistic effects wherein therapeutic efficacy is increased by the generation of reactive oxygen species (ROS) and heat. This review summarizes recent developments in surface-modified and doped CDs for in vitro and in vivo applications, particularly in drug delivery, gene therapy, multimodal imaging, photodynamic therapy (PDT), photothermal therapy (PTT), chemodynamic therapy (CDT), sonodynamic therapy (SDT) and gas therapy, for cancer therapies. Advances in modalities of surface modification that include ligand binding and metal doping have significantly improved CDs’ biocompatibility and targeting precision. However, limitations such as low drug-loading capacity, complex synthesis processes, and the challenges created by hypoxic tumor environments need to be opened for further research. Future directions will focus on enhancing drug-loading efficiency, establishing long-term biocompatibility, and optimizing multifunctional nanocomposite designs for integrated cancer therapies.

Introduction: This work presents an easy one-pot synthesis to prepare carbon dots (CDs) from natural products, and their successful application as photosensitizers (PS) and photothermal agents (PA) to combat bacteria and cancerous cells. Despite some differences may appear in the natural extracts due to the obtaining process, it was possible to obtain antibacterial/antitumor photoactivated nanomedicine from common carbon sources as annatto, cinnamon and curcumin. Methods: Water dispersions of Bixa Orellana L. (annatto), Cinnamomum verum J. Presl (cinnamon), Curcuma longa L. (turmeric or curcumin), and sucrose were used as precursors to prepare CDs1, CDs2, CDs3, and CDs4, correspondingly. The microwave-assisted route was selected to synthesize CDs since it is a simple-timesaving procedure that allows harnessing eco-friendly precursors. The shape, size, and chemical composition of CDs were determined by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier-transform infrared (FTIR) and Raman spectroscopies, respectively. In addition, photodynamic, photothermal, luminescence, cytotoxicity, antimicrobial and antitumor analyses were carried out and assessed. Results and Discussion: This research synthesized irregular shaped CDs, in the range of 2.3 to 3.7 nm, from natural sources. Regarding, their photodynamic and photothermal properties, it was demonstrated that after irradiation CDs generated ¹O₂ species and the temperature can raise in the range to 40– 50 °C, respectively. The antimicrobial capacity of the CDs was tested against microorganism methicillin-resistant S. aureus (MRSA) and Extended-Spectrum β-Lactamase (ESBL)-producing E. coli. CDs1, CDs2, and CDs3 showed excellent antibacterial effects since complete inhibitions were observed after irradiation with blue light (450 nm; 40 mW·cm^{− 2}). In addition, the positive antitumor effect was also evidenced against T47D cells. Therefore, it has been demonstrated that the CDs synthesized from green carbon sources such as annatto, cinnamon and curcumin have potential applications as antibacterial and antitumor nanomaterials.

Photodynamic therapy (PDT) and photothermal therapy (PTT) have shown significant promise in treating cancer and other illnesses. Photosensitizers (PSs) and photothermal agents (PTAs) play crucial roles in PDT and PTT to enhance treatment efficiently. The stability, solubility, and toxicity of PSs and PTAs are the main challenges in improving the effectiveness of these agents. This chapter examines several encapsulation techniques of PS and PTAs agents to reduce these limitations. Liposomes, hydrogels, inorganic particles, metal-organic frameworks, and covalent organic frameworks offer diverse and important strategies for PS, PTAs agents’ delivery. These nanocarrier systems offer unique advantages such as high encapsulation efficiency, sustained drug release, enhanced cytotoxicity against cancer cells, and biocompatibility. Moreover, the nanocapsules create a localized drug depot at the target site and present specific benefits tailored to the requirements of different therapeutic applications, making them valuable tools in developing advanced and targeted drug delivery systems for cancer and other diseases. Overall, the diverse strategies for encapsulating photosensitizers offer unique advantages for enhancing the efficacy and safety of PDT and PTT, making them promising candidates for PDT and drug delivery applications.

Non-melanoma skin cancers (NMSCs), primarily basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are becoming increasingly prevalent. In 2021, the global incidence reached 6.64 million cases, with Australasia and North America exhibiting the highest rates and middle socio-demographic regions experiencing the fastest growth. Photodynamic therapy (PDT) presents a minimally invasive treatment alternative. This study assessed the 10-year long-term efficacy of PDT using methyl aminolevulinate (MAL) for superficial BCC (sBCC)and nodular BCC (nBCC), and 3 patinets with in-situ SCC, after the final PDT treatment. The original group included 64 patients (32 males and 32 female) with 82 histologically confirmed NMSC lesions were initially treated. After 2 months, PDT showed high efficacy: 94.8 % complete response in untreated nBCC, 100 % in recurrent nBCC with dermal invasion after surgery, 92.3 % in sBCC and 100 % in SCC in situ. In contrast, nBCC with perineural invasion after surgery showed no response. Based on these outcomes, 48 patients with 66 lesions were selected for long-term follow-up, and 45 of them completed full clinical follow-up to 10 years. These comprised 11 sBCC, 45 untreated nBCC, 4 nBCC with dermal invasion after surgery, 3 nBCC with perineural invasion after surgery, and 3 in situ SCC. No invasive squamous cell cancers were followed. For sBCC, 72.7 % of lesions achieved complete clearance after the last PDT session, with a 10-year tumor-free survival rate of 70 %. Previously untreated nBCC showed an 80 % complete response after the final PDT session (78 % survival at 5 years), while recurrent dermal-invasive nBCC demonstrated a 100 % complete response. However, PDT proved ineffective for nBCC with perineural invasion (66.7 % recurrence). In-situ SCC lesions achieved a 100 % complete response with sustained 10-year tumor-free survival. Multivariate Cox regression analysis identified age >65 years and tumor thickness >2 mm as factors significantly associated with increased recurrence risk, considering demographic data, lesion characteristics, and PDT treatment parameters. PDT demonstrates notable effectiveness for superficial and nodular BCC, especially with tailored protocols (4 sessions for nodular, 2 for superficial). However, SCC treated with PDT is not a standard therapy for invasive disease and should be undertaken in a clinical trial which requires vigilant long-term surveillance for potential recurrence. PDT is not advised for nodular BCC with perineural invasion. Age and tumor thickness are key prognostic indicators.

In Ecuador, many effluents from the tanning industry have high levels of Cr (VI), generating great environmental impact due to the high toxicity of the metal. An alternative way to remove this contaminant is through adsorbent agents such as magnetic nanoparticles. The objective of the present investigation was to synthesize chitosan-coated magnetite nanoparticles for hexavalent chromium adsorption. The chitosan was obtained from the exoskeleton of the shrimp, and the nanoparticles were synthesized by chemical coprecipitation and coated with chitosan in an In-situ manner. The synthesis was verified by infrared spectroscopy and scanning electron microscopy. The adsorption capacity of hexavalent chromium was performed from adsorption experiments varying the thermodynamic parameters, and the quantification was carried out using UV-Visible spectroscopy. In such a way that chitosan-coated magnetite nanoparticles with an average diameter of 31.85 nm were obtained and the highest adsorption percentage was 99.70%, with a maximum adsorption capacity of 294.12 mg/g at 60 °C, demonstrating that hexavalent chromium adsorption was feasible using chitosan-coated magnetite nanoparticles with better adsorption capacity thanks to the chitosan coating.

Cancer poses a global challenge, affecting millions of people and placing a significant burden on families and healthcare systems. Chemotherapy, radiotherapy, hormone therapy, and immunotherapy are commonly used for cancer treatment; their side effects can be severe. Photothermal therapy (PTT) has emerged as a promising alternative due to its minimal invasiveness and high efficiency. In this study, graphene oxide (GO) was synthesized and functionalized to obtain nitrogen-doped graphene oxide (NGO) and boron-doped graphene oxide (BGO) via a hydrothermal process, aiming to use them as photoactive agents (PAs) in PTT. Atomic force microscopy (AFM) analysis revealed that GO, BGO, and NGO exhibit monolayer atomic structures. Spectroscopic analyses confirmed the presence of oxygen and carbon in all samples, along with successful boron and nitrogen doping in BGO and NGO, respectively. Cytotoxicity assays yielded half-maximal inhibitory concentrations (IC₅₀) of 1025.26 μg/mL for GO, 2695.03 μg/mL for BGO, and 1319.81 μg/mL for NGO. Photothermal experiments were conducted using a 635 nm light source with an intensity of 65.5 mW/cm², resulting in temperature thresholds of 44.87 °C for GO, 48.36 °C for NGO, and 55.91 °C for BGO. Anticancer assays were performed using the T-47D breast cancer cell line, demonstrating tumor cell elimination rates of 97.93% for GO, 98.54% for BGO, and 97.98% for NGO, underscoring their efficacy as PAs. Density functional theory (DFT) simulations were carried out to determine the absorbance coefficient as a function of doping percentage. The results revealed that increased doping enhances light absorbance and, consequently, the photothermal response, as higher absorbance at the irradiation wavelength leads to greater energy absorption and temperature elevation.