Polysaccharide-Modified Gold Nanorod and Polydopamine Nanocarriers for Near-Infrared Light-Responsive Biomedical Applications: A Comparative Review

Near-infrared (NIR)-responsive nanocarriers offer spatially and temporally controlled heating, drug release, and imaging for biomedical applications. Gold nanorods (AuNRs) and polydopamine (PDA) are two widely investigated platforms with complementary properties: AuNRs provide spectrally tunable plasmonic heating and strong optical imaging capability, whereas PDA offers broadband absorption, adhesive surface chemistry, high cargo-loading capacity, and compatibility with hydrogels and regenerative matrices. Polysaccharide modification can improve physiological stability, reduce nonspecific biological interactions, and introduce receptor targeting, mucoadhesion, or microenvironment responsiveness. This review compares the conjugation chemistry, therapeutic mechanisms, pharmacokinetics, biosafety, and biomedical applications of polysaccharide-modified AuNR and PDA systems, with emphasis on tumor therapy, antibacterial treatment, wound repair, and local drug delivery. AuNR-based platforms are most suitable when rapid wavelength-selective heating and image guidance are primary requirements, whereas PDA-based systems are generally better suited to sustained delivery, tissue adhesion, and long-term local integration. We further discuss AuNR–PDA hybrid architectures and identify key translational barriers, including inconsistent characterization, uncertain long-term fate, nonstandardized photothermal dosimetry, and limited manufacturing reproducibility. This function-oriented comparison provides a practical framework for selecting polysaccharides and carrier platforms according to administration route, biological barrier, therapeutic objective, and safety requirements.