Background: Superparamagnetic properties and excitation independence have been incorporated into carbon-decorated manganese ferrite nanodots (MnFe@C) to introduce an economical and safer multimodal agent for use in both T1-T2 MRI and fluorescence-based imaging to replace the conventional highly toxic heavy metal contrast agents. Methods: The surface conjugation of 8-anilino-1-naphthalenesulfonate (ANS) to MnFe@C nanodots (ANS-MnFe@C) enhances both longitudinal and transverse MRI relaxation, improves fluorescence for optical imaging, and increases protein detection sensitivity, showing higher multimodal efficacy in terms of molar relaxivity, radiant efficiencies, and fluorescence sensitivity compared to MnFe@C. Results: The band gap energy was determined using Tauc’s equation to be 3.32 eV, while a 72% quantum yield demonstrated that ANS-MnFe@C was highly fluorescent, with the linear range and association constant calculated using the Stern–Volmer relation. The synthesized ANS-MnFe@C demonstrated excellent selectivity and sensitivity for bovine serum albumin (BSA), with a nanomolar detection limit of 367.09 nM and a broad linear range from 0.015 to 0.225 mM. Conclusions: In conclusion, ANS-MnFe@C holds ease of fabrication, good biocompatibility, as assessed in A375 cells, and an effective pH-sensitive doxorubicin release profile to establish anticancer activity in lung cancer cell line (A549), highlighting its potential as an affordable therapeutic agent for multimodal imaging, drug delivery, and protein sensing.

Background and purpose: Despite significant advancements in cancer therapies, chemotherapeutics continue to be the mainstay for treating cancer patients, with 5-fluorouracil (5-FU) being commonly used for various cancers. However, its limited ability to penetrate cell membranes and its short half-life, caused by rapid metabolism, necessitate frequent administration of high doses to maintain effective therapeutic levels. This study aimed to synthesize oxidized sodium alginate (OSA) derivatives to create OSA nanoparticles loaded with 5-FU (OSANP@ 5-FU), promoting diketo tautomers, and evaluate their photophysical properties, release profile, and anticancer activity with minimal toxicity. Experimental approach: The investigation encompassed physicochemical characterization, encapsulation efficiency, 5-FU release kinetics at pH 2.2 and 7.4, cell viability assessment via MTT assay in V79 cells, and in vitro anticancer efficacy in the A375 cell line. Key results: Steady-state absorption and emission confirmed the presence of advantageous diketone tautomers of 5-FU, indicating radiative transitions from the second singlet excited state to the ground state (S2S0) and the drug's encapsulation within the polymeric nanostructure. Dynamic light scattering revealed that OSA nanoparticles, initially 177.8 nm, grew to 226.6 nm after encapsulating 5-FU, retaining high zeta potential for stability. With a 68% encapsulation efficiency, in vitro studies showed 46 to 54 % of 5-FU released across different pH levels within 510 minutes. Conclusion: In acidic conditions, there is a greater release of 5-FU than neutral pH levels, indicating a pH-responsive release profile beneficial for cancer treatment, with the release mechanism of OSANPs following Fickian diffusion as identified by a Korsmeyer-Peppas mathematical model and the formu¬lation showing improved therapeutic efficacy.

Background and purpose: Multifunctional nanoparticles (NPs) are gaining significant interest in biomedical research because of their versatility and potential across various applications, especially in cancer imaging and therapy. These composite systems consist of assorted materials, such as metallic elements, metal oxides, polymers, and carbon-based nanostructures, that are combined to form a single platform featuring improved and synergistic properties. Experimental approach: This study aims to design and synthesize a novel class of silver-coated carbon dot-capped manganese ferrite NPs that were functionalized with lipids (L-Ag@MnFe@C) to improve their cytocompatibility and enable cancer therapy with multimodal imaging functionalities. Carbon-capped manganese ferrite NPs (MnFe@C) were synthesized by a one-pot hydrothermal method, followed by the fabrication of nano-silver coated over the surface (Ag@MnFe@C) using a modified Tollens method, and lipid functionalization was done by the rotary evaporation method for the development of low-cost and biodegradable theranostic agents. Key results: The physicochemical characterization reveals that the engineered L-Ag@MnFe@C exhibits a higher stability, with a zeta potential of -50.6 mV, a hydrodynamic diameter of 279.4 nm and a quantum yield of 69.4 %. The engineered NPs exhibit contrast capabilities in longitudinal magnetic resonance imaging, transverse magnetic resonance imaging, fluorescence imaging, and computed tomography imaging. Furthermore, L-Ag@MnFe@C demonstrated excellent anticancer activity on the lung cancer cell line (A549). Conclusion: Based on these studies, it can be concluded that the engineered L-Ag@MnFe@C exhibits multimodal imaging abilities and demonstrates anticancer properties, thereby confirming it as a potential theranostic agent.