# Research Progress of Polysaccharide-Gold Nanocomplexes in Drug Delivery
## 5 Research on polysaccharide-AuNPs as Drug Delivery Carriers  
Drugs can be directly bound to the surface of AuNPs through covalent and non-covalent interactions (Figure 6). When employing polysaccharide-AuNPs for drug delivery, medications can be attached to the nanomaterials via several methods, including physical coating, chemical grafting, or electro-attraction. The diverse binding modes of polysaccharide-AuNPs enable the delivery of a wide array of drugs, encompassing small molecule drugs, nucleic acids, proteins, and peptides [106]. In addition, the surface of AuNPs can be modified to facilitate drug encapsulation and delivery. Depending on the properties of the drug, various modifications can be performed on polysaccharide-AuNPs to meet the needs of delivering different types of drugs. Furthermore, the binding of proteins or peptides to AuNPs can occur through electrostatic interactions. DNA is negatively charged due to the phosphate backbone. However, most AuNPs, commonly used in academic research, also have a negative charge on their surface. This poses a challenge when attempting to combine nucleic acids with AuNPs using electrostatic adsorption. As a result, modifying the AuNPs or the nucleic acids is necessary for successful integration. The most commonly employed method involves changing the nucleic acids through sulfhydryl modification. It has been demonstrated that AuNPs with diameters ranging from 1 to 100 nm can successfully accommodate a significant quantity of sulfhydryl-modified oligonucleotides. Consequently, this technique offers a valuable strategy for incorporating nucleic acids into AuNPs [107]. To enhance the delivery of various payloads, it is essential to functionalize AuNPs. This can be achieved through multiple methods, including glycation, peptide, and amino acid binding, or by functionalizing them with oligonucleotides. The functionalization process enables AuNPs to transport and deliver a diverse range of payloads effectively [108]. Modification of nanomaterials can improve their stability and targeting capabilities and broaden the range of nanomaterial applications. The function of gold nanometers is influenced by the material bound to its surface and the nanometer's size and molecular weight. Polyethylene glycol (PEG) modification is a widely used method for nanomaterials. PEG, being highly biocompatible and hydrophilic, offers several advantages. Firstly, it improves the colloidal stability of nanoparticles, promoting their long-term dispersion in a liquid medium. Secondly, using PEG reduces the immunogenicity of nanoparticles, minimizing the potential immune response upon their introduction into a biological system [109]. Finally, PEG modification prolongs the circulation time of nanoparticles in vivo, enhancing their therapeutic effectiveness. PEG-modified AuNRs exhibit a favorable photothermal effect and demonstrate exceptional efficacy in ablating cervical cancer cells using NIR irradiation [110]. Peptide-modified gold nanoparticles have been widely recognized for their bioactivity in various fields, such as drug delivery, cancer therapy, targeting, and biosensors. The complex's selectivity can be improved by adjusting the density or orientation of the coupled peptide [111]. For instance, [PERSON] et al. utilized arginine-glycine-aspartate-like peptide-modified gold nanoparticles in their study of cancer diagnosis and therapy, which showed higher accumulation in subcutaneous tumors than unmodified gold nanoparticles, and similar results were obtained in an intracranial tumor model, which demonstrated better penetration of the blood-brain barrier, which initially proves its application in a wide range of tumors. However, more in-depth characterization still needs to be conducted [112]. The efficacy of gold nanoparticles modified with cell-penetrating peptides (CPPs) will be evaluated in terms of their ability to target cancer cells selectively and potentially enhance normal fibroblast function [113]. In a recent study, [PERSON] et al.