Targeted photodynamic therapy for colorectal cancer using antibody-conjugated green-synthesised nanoparticles

Colorectal cancer (CRC) remains a major clinical challenge due to the persistence of epithelial cell adhesion molecule (EpCAM) positive (+) cancer stem cells (CSCs), which drive tumour relapse, metastasis, and immune evasion. This review highlights a modular nanomedicine construct, EpAb2‑6‑AuNPs‑PPBa, designed for targeted photodynamic therapy (PDT) in CRC. By integrating EpCAM‑specific antibodies (EpAb2‑6), gold nanoparticles (AuNPs) synthesised through plant extracts, and photosensitiser (PS) such as pheophorbide‑a (PPBa). Upon near‑infrared activation, PPBa generates reactive oxygen species (ROS), inducing immunogenic cell death (ICD) characterised by calreticulin exposure, ATP release, and HMGB1 secretion. The system also incorporates surface‑enhanced Raman scattering (SERS) tags for real‑time imaging and circulating tumour cell (CTC) capture. Green synthesis provides biocompatibility and scalability, and antibody guidance enhances tumour specificity. By critically evaluating antibody selection, AuNPs synthesis strategies, and photosensitiser performance, this review situates EpAb2‑6‑AuNPs‑PPBa within the broader perspective of CRC nanotheranostics. Although rigorous in vivo validation and translational studies are necessary, the construct exemplifies a sustainable, multifunctional approach to precision oncology.