Uptake of luminescent colloidal Ag–In–S nanoprobes by BC cells differing in metastasis propensity

• Developed colloidal silver-indium-sulphur (Ag-In-S) quantum dots (QD) displayed high photoluminescence quantum yields. • QD coated with mercaptopropionic acid (MPA) or branched polyethyleneimine (BPEI) showed distinct size distributions and cellular interactions. • Highly metastatic breast cancer cells internalized 1.5-1.7 times more QD compared to lowly metastatic cells. • MPA-coated quantum dots displayed no toxicity, while BPEI-coated QD induced rapid cell death, highlighting their selective effects. • Findings suggest Ag–In–S nanoprobes as potential tools for assessing cancer cell metastasis and enhancing targeted diagnostics and therapy. This study investigates the metastasis-dependent cellular uptake of luminescent colloidal silver–indium–sulfur (Ag–In–S) nanoprobes in breast cancer (BC) cells. We developed water-soluble fluorescent semiconductor nanocrystals (quantum dots, QDs) that exhibit exceptional brightness, remarkable photostability, and impressive resistance to photobleaching. The Ag–In–S quantum dots, coated with either mercaptopropionic acid (MPA–Ag–In–S) or branched polyethyleneimine (BPEI–Ag–In–S), demonstrate a broad emission spectrum ranging from deep red to bluish green, achieving photoluminescence quantum yields of up to 47 %. The absorption spectra revealed peaks ranging from 290 nm to 440 nm, with a persistent peak at 555 nm observed across all quantum dots. The size of MPA–Ag–In–S nanoparticles ranged from 2 to 5 nm, while BPEI-–Ag–In–S nanoparticles ranged from 150 to 200 nm. We employed a scanning microplate fluorometer to accurately measure the cellular uptake of QDs, normalizing the fluorescence data based on DNA content quantified using Hoechst 33,342 dye. Our findings revealed that cells exhibiting high MP internalized significantly more QDs compared to those with low MP, showing an increase of 1.5–1.7 times. Toxicity assays demonstrated that MPA–Ag–In–S QDs exhibited no toxic effects on both high and low MP cells. In contrast, BPEI–Ag–In–S QDs caused substantial cell death within just one hour of exposure. Comparative analysis with commercially available nanoparticles highlighted the superior concentration and fluorescence properties of our synthesized QDs. These results indicate that Ag–In–S nanoprobes may be a powerful tool for distinguishing the metastatic potential of cancer cells, presenting a promising avenue for enhanced targeted cancer diagnostics and treatment.