Synthesis, characterisation, and anti-tumour activity of nano-immuno-conjugates for enhanced photodynamic therapy of oesophageal cancer stem cells

In recent times, oesophageal cancer has been listed as the eleventh most prevalent type of cancer. It is a lethal disease attributed to a high mortality rate, tumour metastasis and poor treatment outcome. A subset of oesophageal cancer referred to as stem cells (CSCs) has been revealed to drive carcinogenesis, metastasis, and treatment failure. Therefore, it is essential to target these CSCs to improve the efficacy of treatment for oesophageal cancer. In this present study, we employed a strategy to target oesophageal CSCs with a nano-immuno-conjugate (NIC) consisting of AlPcS₄Cl, gold nanoparticle (AuNPs) and anti-CD271 antibody synthesised using a chemical reaction. The synthesised NIC was characterised using ultraviolet-visible spectroscopy, transmission electron microscope (TEM), Fourier transform infra-red (FTIR) spectroscopy, dynamic light scattering (DLS), and zeta potential (ZP). The in vitro anti-tumour action of NIC-mediated photodynamic therapy (PDT) was performed on oesophageal CSCs using cell viability/cytotoxicity assays and morphological examination via light microscopy. The characterisation analysis confirmed the successful synthesis of the NIC. The synthesised nano-immuno-conjugates showed significant cytotoxicity and reduction in cell viability in the HKESC-1 oesophageal CSCs. Fluorescence microscopy confirmed the rapid internalisation of the targeted NIC in key cellular organelles of the CSCs, resulting in enhanced effects. Interestingly, NIC exhibited cytocompatibility with non-tumour WS1 cells, thus supporting its clinical application as a safe anti-tumour agent for enhanced PDT. The study demonstrates the improved effects of NIC-mediated PDT as targeted therapeutics against oesophageal CSCs.