Divergent Responses of Hydrophilic CdSe and CdSe@CdS Core-Shell Nanocrystals in Apoptosis and In Vitro Cancer Cell Imaging: A Comparative Analysis.

With their distinctive core-shell design, core-shell nanocrystals have drawn interest in catalysis, medicinal research, and nanotechnology. These nanocrystals have a variety of characteristics and possible uses. The application of core-shell nanocrystals offers significant potential in increasing diagnostic and therapeutic approaches for cancer research in apoptosis and in vitro cancer cell imaging. In the present study, we investigated the fluorescence behavior of hydrophilic CdSe (core-only) and CdSe@CdS (core-shell) nanocrystals (NCs) and their potential in cancer cell imaging. The addition of a CdS coating to CdSe NCs increased the fluorescence intensity tenfold. The successful fabrication of core-shell CdSe@CdS nanocrystals was proven by a larger particle size (evaluated via DLS and TEM) and their XRD pattern and surface morphology compared to CdSe (core-only) NCs. When these NCs were used for bioimaging in MCF-7 and HEK-293 cell lines, they demonstrated excellent cellular uptake due to higher fluorescence intensity within cancerous cells than normal cells. Comparative cytotoxicity studies revealed that CdSe NCs were more toxic to all three cell lines (HEK-293, MCF-7, and HeLa) than CdSe@CdS core-shell structures. Furthermore, a decrease in mitochondrial membrane potential and intracellular ROS production supported NCs inducing oxidative stress, which led to apoptosis via the mitochondria-mediated pathway. Increased cytochrome c levels, regulation of pro-apoptotic gene expression (e.g., p53, Bax), and down-regulation of Bcl-2 all suggested cellular apoptosis occurred via the intrinsic pathway. Significantly, at an equivalent dose of core-shell NCs, core-only NCs induced more oxidative stress, resulting in increased apoptosis. These findings shed light on the role of a CdS surface coating in reducing free radical release, decreasing cytotoxicity, and improving fluorescence, advancing the field of cell imaging.

Visible Laser Light Mediated Cancer Therapy via Photothermal Effect of Tannin-Stabilized Magnetic Iron Oxide Nanoparticles.

Super-paramagnetic iron oxide nanoparticles (SPIONs/Fe3O4) were synthesized in aqueous medium under a nitrogen atmosphere. These particles were made water-dispersible by cladding them with tannic acid (TA). The synthesized nanoparticles were characterized for their size and surface charge using HRTEM and zetasizer. It was found that the size of the particles formed was around 15 nm with almost spherical morphology and negative surface charge. Vibrating sample magnetometer (VSM) data attributed a super-paramagnetic nature to these nanoparticles. The photo-thermal dynamics of these magnetite (Fe3O4) nanoparticles was characterized by exciting their dispersions with laser radiation in the visible region (635 nm). Remarkably, 17 min of laser irradiation of the dispersion raised its temperature by ~25 °C (25 to 49.8 °C), whereas for the solvent, it was limited to not more than 4 °C (after 60 min). Thus, the Fe3O4 nanoparticles generated localized hyperthermia for potential use in cancer therapy of tumor management. The photo-thermal dynamics of these nanoparticles was investigated in-vitro for cancer therapy, and it was clearly shown that cancer cell growth was inhibited, and considerable cellular damage occurred when cells were incubated with laser-activated magnetic nanoparticles. No noticeable innate toxicity of the nanoparticles was observed on cancer cell lines. The effectiveness of these nanoparticles was studied on several malignant cell lines, and an acceptable Fe3O4 concentration range was subsequently determined for generating substantial cell death by hyperthermia, but not inherent toxicity. Therefore, we concluded that this nano-system is effective and less time consuming for the treatment of malignant diseases such as cancer.

Comparative In Vitro Cytotoxicity Study of Carbon Dot-Based Organometallic Nanoconjugates: Exploration of Their Cell Proliferation, Uptake, and Localization in Cancerous and Normal Cells.

Organometallic nanoconjugates have raised great interest due to their bimodal properties and high stability. In the present study, we analyzed the cytotoxicity property of carbon dots (CDs) and a series of organometallic nanoconjugates including gold@carbon dots (Au@CDs) and silver@carbon dots (Ag@CDs) synthesized via an aqueous mode. We aimed to divulge a comparative analysis of cell proliferation, uptake, and localization of the particles in HeLa and HEK293 cell lines. Our results showed dose-dependent cytotoxicity of Au@CDs, Ag@CDs, and CDs. However, Ag@CDs showed the highest inhibition through HeLa cells with an IC50 value of around 50 ± 1.0 µg/mL. Confocal imaging signified the uptake of the particles suggested by blue fluorescence in the interior region of HeLa cells. Furthermore, the TEM micrographs depicted that the particles are entrapped by endocytosis assisted through the cell microvilli. The CDs and Au@CDs were thus observed to be relatively safe up to a concentration of 100 µg/mL and did not induce any morphological changes in the cells. Moreover, the cell proliferation assay of these nanoconjugates against HEK 293 cells signified the nontoxic nature of the nanoconjugates. The results thus revealed two major facts: firstly, the Ag@CDs had potent therapeutic potential, signifying their potential as a promising anticancer drug, and secondly, the CDs and Au@CDs at a defined dose could be used as probes for detection and also bioimaging agents.