# Research Progress of Polysaccharide-Gold Nanocomplexes in Drug Delivery
## 5 Research on polysaccharide-AuNPs as Drug Delivery Carriers
investigated the role of erythrocyte membranes and antibody-modified AuNRs as nanocarriers for improving antitumor effects. Their findings suggest that these nanocarriers may be able to diagnose and treat pancreatic cancer through active targeting [114]. [PERSON] et al. demonstrated superior radiosensitization with albumin-AuNPs compared to AuNPs alone. Additionally, the albumin-AuNPs showed effective tumor accumulation. These findings highlight the potential for relatively greater radiosensitization and antitumor activity while minimizing damage to normal body tissues, but pharmacokinetic studies, validation of tumor models, and investigation of the mechanism of radiosensitization were lacking in this experiment [115]. Thioglycolic chitosan-coated gold nanoshells (TC-AuNSs) can be used as antimicrobial agents against a variety of bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, which destroy antibiotic-resistant pathogens under NIR laser light to efficiently and rapidly kill the bacteria and prevent bacterial regeneration [116]. AuNPs have the capability to adsorb proteins, resulting in the formation of protein-coated AuNPs [117]. These protein-coated AuNPs are commonly employed for the targeted delivery of proteins or polypeptides to specific locations. The adsorption mechanism might be attributed to electrostatic interactions between the negatively charged surface of AuNPs and the proteins' positively charged amino acid residues, resulting in protein attachment to the AuNPs surface. Another plausible mechanism could involve protein neutrality when the pH approaches its isoelectric point. The protein's electrostatic adsorption with AuNPs might diminish at pH values near its isoelectric end. However, given the considerable surface tension of the protein and its weakly hydrated state, it becomes more prone to adsorption onto the AuNPs surface. [PERSON] et al. [118] conducted a study in which they loaded a matrix metalloproteinase-2 (MMP2)-responsive M2 pep fusion peptide (M-M2 pep) onto the surface of hyaluronic acid-modified AuNRs. The researchers found that M-M2 pep was released from the AuNRs when exposed to NIR light irradiation. This release of M-M2 pep resulted in an enhancement of the immunoreactivity of the tumor microenvironment (TME). Additionally, the study demonstrated that HA-AuNRs facilitated precise photothermal therapy (Figure 7C) [118]. [PERSON] et al. conducted a study focused on synthesizing AuNPs using Lactobacillus plantarum extracellular polysaccharides (EPS) through green technology. The study was conducted to develop a novel nanocarrier for the delivery of multiple antibiotics to treat multidrug-resistant (MDR) bacterial infections effectively. Experiments demonstrated that the nanocarriers possessed excellent bacterial inhibitory activity, but investigations still need to be carried out in animal models to investigate their optimal antibacterial activity and biodistribution [119]. Polysaccharide-based nanocarriers have emerged as critical players in oral drug delivery. Their molecular structure enhances their binding efficiency and stability with proteins/peptides. This is due to their desirable characteristics, including low immunogenicity, high biocompatibility, and effective lymphatic absorption [120]. Bone morphogenetic pro tein 2 (BMP-2) is a soluble peptide that can activate cartilage formation. However, its high diffusivity leads to inadequate uptake by target cells, thus limiting its application. [PERSON] et al. aimed to address this issue by utilizing HA-AuNRs to bind to the peptide. Through this approach, they could effectively enhance the peptide uptake by the cells, ultimately promoting cartilage repair and regeneration [121]. There are electrostatic repulsive forces between nucleic acids and AuNPs, which prevent their combination. However, adding salt can gradually reduce these awful forces, ultimately allowing for the binding of AuNPs and nucleic acids [122].