Endocrine-disrupting chemicals (EDCs) threaten many kinds of life throughout the world. These compounds function the same as sexual hormones, inducing precocious puberty, gynecomastia, etc., in the human body. To prevent excess exposure to nonylphenol (NP), a simple and rapid detection system is needed. In this study, we develop a nonylphenol-specific aptamer from a random single-stranded DNA library and test a rapid sensor system based on the aptamer and gold nanoparticles (AuNPs). The aptamer was screened by a methodology involving reduced graphene oxide (rGO). As a result of screening and sequencing, a DNA aptamer was developed that recognizes the target with high binding affinity (K_d = 194.2 ± 65.9 nM) and specificity. The sensor system developed using the aptamer and gold nanoparticles is sensitive (LOD = 2.239 nM). Circular dichroism (CD) spectrometry results show that the free aptamer binds to the target molecule. The aptamer was characterized using gold nanoparticles to measure UV absorbance. Our results suggest that the sensor system developed using this aptamer is useful for field diagnosis of small molecules.

Avian influenza (AI) has severely affected the poultry industry worldwide and has caused the deaths of millions of birds. Highly pathogenic avian influenza virus is characterized by high mortality and the ability to transmit from birds to humans. Early diagnosis is difficult because of the variation in pathogenicity and the genetic diversity between virus subtypes. Therefore, development of a sensitive and accurate diagnostic system is an urgent priority. We developed ssDNA aptamer probes to detect AI viruses. Through seven rounds of SELEX to search for a probe specific to the highly pathogenic AI virus subtype H5N1, we identified 16 binding aptamers and selected two with the highest binding frequency. These two aptamers had strong binding affinities and low detection limits. We found that they could bind more specifically to H5N1, as compared to other subtypes. Furthermore, these aptamers inhibited hemagglutination, which is caused by the virus surface protein hemagglutinin. Our results indicate that our screened aptamers are effective molecular probes for diagnosing H5N1 and can be used as therapeutic agents to inhibit viral surface proteins. Sensitive diagnosis and suppression of avian influenza will help maintain a stable and healthy livestock industry, as well as protect human health.

Diabetes is one of the top 10 global causes of death. About one in 11 global adults have diabetes. As the disease progresses, the mortality rate increases, and complications can develop. Thus, early detection and effective management of diabetes are especially important. Herein, we present a novel glycated human serum albumin (GHSA) aptamer, i.e., GABAS-01, which has high affinity and specificity. The aptamer was selected by reduced graphene oxide-based systematic evolution of ligands by exponential enrichement (rGO-based SELEX) against GHSA. After five rounds of selection through gradually harsher conditions, GABAS-01 with high affinity and specificity for the target was obtained. GABAS-01 was labeled by FAM at the 5′-end and characterized by measuring the recovery of a fluorescence signal that is the result of fluorescence quenching effect of rGO. As a result, GABAS-01 had low-nanomolar Kd values of 1.748 ± 0.227 nM and showed a low limit of detection of 16.40 μg/mL against GHSA. This result shows the potential application of GABAS-01 as an effective on-site detection probe of GHSA. In addition, these properties of GABAS-01 are expected to contribute to detection of GHSA in diagnostic fields.

The plant disease Phytophthora blight, caused by the oomycete pathogen Phytophthora capsici, is responsible for major economic losses in pepper production. Microtubules have been an attractive target for many antifungal agents as they are involved in key cellular events such as cell proliferation, signaling, and migration in eukaryotic cells. In order to design a novel biocompatible inhibitor, we screened and identified inhibitory peptides against alpha- and beta-tubulin of P. capsici using a phage display method. The identified peptides displayed a higher binding affinity (nanomolar range) and improved specificity toward P. capsici alpha- and beta-tubulin in comparison to Homo sapiens tubulin as evaluated by fluorometric analysis. One peptide demonstrated the high inhibitory effect on microtubule formation with a nanomolar range of IC₅₀ values, which were much lower than a well-known chemical inhibitor—benomyl (IC₅₀ = 500 µM). Based on these results, this peptide can be employed to further develop promising candidates for novel antifungal agents against Phytophthora blight.