# Moving towards Personalized Medicine--The Broad Use of Aptamers for Targeted Theranostic
## 2 Cancer Therapeutics
### Microbiota and Infection
They can be used in combination with high-throughput sequencing technologies, such as 16S rRNA sequencing to identify and quantify specific microbial populations in the gut microbiota and to identify and quantify specific microbial metabolites, which are important for gut health [118]. This approach allows researchers to better understand the interactions between the microbiome and the host and how they influence overall health and disease, providing a more accurate diagnosis and better understanding of the disease [119, 120, 121, 122, 123]. Attamers can also be used in therapy to target and modulate specific microorganisms, or to target drug delivery in the gut microbiota. For example, [PERSON] et al. (2015) designed aptamers to selectively bind to viral proteins or other molecules involved in viral replication and infection with high specificity and sensitivity, preventing their replication or disrupting their functions [124]. Here, the authors discuss several examples of aptamer-based assays developed for the detection of hepatitis C and Human Immunodeficiency Virus (HIV) and also how this novel method could be used as a therapeutic agent for viral infections, such as influenza, with A-20 and V46 aptamers [119; 120], dengue fever, with S15G3 aptamer [121], and Zika virus [122]. Additionally, aptamers can be used to deliver therapeutic molecules, such as antibiotics, antivirals, antifungals, or probiotics, specifically to the site of infection or dysbiosis in the human microbiota, reducing side effects and increasing efficacy [123]. They can also be used to deliver therapeutic nucleic acids, such as small interfering RNA (siRNA) or microRNA (miRNA), to downregulate the expression of viral genes or host cell genes that are essential for infection [124]. Several studies have also demonstrated the use of aptamers in detecting specific microbial targets in gastrointestinal dysbiosis, such as detecting Clostridium difficile with the ARH1t6 aptamer [125] in addition to using others to detect gut pathogens such as Salmonella [126] and _Escherichia coli_[127]. Aptamers have also shown potential in the treatment of gastrointestinal diseases, specifically targeting and inhibiting the growth or virulence of pathogens such as _Helicobacter pylori_, a bacterium known to cause peptic ulcer and gastric cancer. The aptamer HPA-2 has shown potential for the detection of _H. pylori_, demonstrating high specificity within a limit of detection of 88 cfu/mL [128]. In addition to the mentioned applications, aptamers can also be used to monitor changes in microbiota and detecting shifts in the microbial community, allowing for the identification of potential health risks or the monitoring of the effectiveness of treatments [129]. The use of aptamers in gut microbiota research is still in its early stages and there is significant potential for future applications. Aptamers have the potential to be used as a diagnostic tool for gut microbiota-related disease, such as inflammatory bowel disease and colorectal cancer, but also for gut microbiota-related diseases, such as antibiotic-resistant infections [123]. Moreover, aptamers can be integrated with other technologies, such as high-throughput sequencing and mass spectrometry, to provide a more comprehensive analysis of the gut microbiota [130]. This approach has the potential to provide a more detailed understanding of the gut microbiota and its role in human health and disease.