# Research Progress of Polysaccharide-Gold Nanocomplexes in Drug Delivery
## 4 Application of polysaccharide-AuNPs
Polysaccharide-AuNPs exhibit many distinctive bioactivities, marked antimicrobial properties, and versatility as indicators and biosensors. [PERSON] et al. conducted a study to evaluate the in vitro proliferative activity, antimicrobial activity, and antifungal activity of longan polysaccharide-AuNPs. The results of this study demonstrated that the prepared longan polysaccharide-AuNPs exhibited excellent in vitro proliferative activity and in vitro antimicrobial and antifungal activity [87]. The design of AuNPs-based biosensors follows a fundamental principle by functionalizing or covering the AuNPs with thiolated biomolecules. This modification significantly changes the light absorption of the AuNPs when they come into contact with complementary biomolecules [91]. Depending on the color change, the AuNPs obtained by [PERSON] et al. using marine algal polysaccharides can serve as convenient, reliable, safe, and inexpensive time-temperature indicators for monitoring the quality and safety of perishable bioproducts. However, their application in practical production still needs to be studied for improvement [92]. Meanwhile polysaccharide gold nanosystems have been widely used to prepare various biodetectors due to their convenience, speed, and sensitivity. In 1997, [PERSON] et al. made a significant advancement in using nanomaterials for virus detection by combin  
Figure 5: (**A**): Chloroauric acid–mediated glycosidic bond–breaking synthesized gold nanoparticles. (**B**): Base–mediated glycosidic bond–breaking synthesized gold nanoparticles. Reproduced with permission from Ref. [88]. (**C**): Gold nanosynthesis with halogenated gold salts (**a**) to generate seeds (**b**), which in turn form well-defined shapes (**c**). Reproduced with permission from Ref. [71]. ing AuNPs with silver staining to detect HPV in cervical cancer cells. This pioneering work marked an important turning point in the field [93]. The attachment of hyaluronic acid (HA)-functionalized AuNPs/polyetherimide (PEI)-stabilized/rhodamine B (RhB) (AuNPs/PEI/RhB-HA) materials to CD44 receptor overexpressing MCF-7 cancer cells has been investigated as a means of developing specific probes for in vivo cancer diagnosis. However, the method was less biocompatible, and the effects were not explored [94]. [PERSON] et al. synthesized chitosan-capped AuNPs for simple, rapid, and green detection of Mycobacterium tuberculosis (MTB) by PCR, but the protocol has a small scope of application because free chitosan in AuNPs preparation affects the results of the experiments and there is difficulty in performing the assay on multiple samples [95]. The abuse of antibiotics worldwide has led to bacterial infections becoming a significant threat. Extensive research has been conducted on various gold-based nanostructures as potential antibacterial agents. These nanostructures exhibit exceptional chemical and physical characteristics, making them promising tools to fight against bacterial infections [96]. In their research, [PERSON] et al. conducted a study to investigate and assess the antimicrobial properties of metal AuNPs. Specifically, they examined the effects of Au, Ag, and Cu nanoparticles when combined with HA. The objective of this study was to determine the antimicrobial efficacy of the combination of these metal AuNPs with HA. The authors' findings indicate that the collective use of metal AuNPs (Au, Ag, Cu) with HA significantly increases in antimicrobial activity, surpassing the effects observed with individual metal nanoparticles or HA alone [97]. Chitosan (CH) is a natural polysaccharide derived from chitin, a substance found in the shells of crustaceans. It has been widely studied for its antimicrobial properties and has shown great potential in various applications, including drug delivery and wound healing. Both CH and silver AuNPs have demonstrated potent antibacterial activity.