Background: Metal-free, water-soluble and highly stable meso-tetra-(4-sulfonatophenyl) porphyrin (TPPS₄) has been studied for their singlet oxygen quantum yield. However, TPPS₄ suffers from inherent shortcomings. To address these, TPPS₄ was conjugated to ternary copper indium sulphide/ zinc sulphide (CuInS₂/ZnS) quantum dots (QDs). Purpose: We herein report for the first time the synthesis of TPPS₄–CuInS/ZnS QDs conjugate as an improved photosensitizer. Methods: Water-soluble TPPS₄ was synthesized from tetraphenylporphyrin (TPPH₂) after silica-gel purification. The CuInS/ZnS QDs were synthesized by hydrothermal method at a Cu:In ratio of 1:4. The porphyrin–QDs conjugate was formed via the daggling sulfonyl bond of the porphyrin and amine bond of the QDs. The effect of pH on the optical properties of TPPS₄ was evaluated. The effect of Zn:Cu + In ratio on the ZnS shell passivation was examined to reduce structural defects on the as-synthesized QDs. Results: Various spectroscopic techniques were used to confirm the successful conversion of the organic TPPH₂ to water-soluble TPPS₄. The singlet oxygen generation evaluation shows an improved singlet oxygen quantum yield from 0.19 for the porphyrin (TPPS₄) alone to 0.69 after conjugation (CuInS/ZnS-TPPS₄) with an increase in the reaction rate constant (k (s-1)).

The link between the microbiome and cancer has led researchers to search for a potential probe for intracellular targeting of bacteria and cancer. Herein, we developed near infrared-emitting ternary AgInSe/ZnS quantum dots (QDs) for dual bacterial and cancer imaging. Briefly, water-soluble AgInSe/ZnS QDs were synthesized in a commercial kitchen pressure cooker. The as-synthesized QDs exhibited a spherical shape with a particle diameter of 4.5 ± 0.5 nm, and they were brightly fluorescent with a photoluminescence maximum at 705 nm. The QDs showed low toxicity against mouse mammary carcinoma (FM3A-Luc), mouse colon carcinoma (C26), malignant fibrous histiocytoma-like (KM-Luc/GFP) and prostate cancer cells, a greater number of accumulations in Staphylococcus aureus, and good cellular uptake in prostate cancer cells. This work is an excellent step towards using ternary QDs for diagnostic and guided therapy for prostate cancer.