Biomimetic porous silicon for rationally engineered combination therapy to induce immunogenic cell death

Combined chemo-photothermal therapy (CHT-PTT) is a promising treatment for metastatic cancers. It enables the synergistic induction of immunogenic cell death (ICD), while sensitising suppressive tumour microenvironment to immunotherapy. To induce ICD, the rational design of a combined CHT-PTT regimen remains unclear. In the present study, black porous silicon nanoparticles (BPSi NPs) were utilized as both drug carriers and photothermal conversion agents. To enhance their colloidal stability and homotypic targeting, BPSi NP surfaces were modified with polyethylene glycol and further coated with cancer cell membranes (CMs). Six chemotherapeutic drugs with different cell growth inhibition mechanisms were tested against metastatic MDA-MB-231 breast cancer cells to evaluate their ICD induction potentials. Finally, in the combined CHT-PTT, the effect of temperature was evaluated. Based on the analysis of ICD markers, high-mobility group box 1 and calreticulin proteins, we found that bromodomain-containing protein 4 inhibitor, (+)-JQ-1 (JQ1) was the optimal drug, and the mild-hyperthermia temperature of 45 °C was the best temperature setting in the combined CHT-PTT to induce ICD. Thus, our study provides rationally designed CHT-PTT regimen for efficient cancer treatment with high efficacy and low side effects.