Applicability of a Green Nanocomposite Consisted of Spongin Decorated Cu2WO4(OH)2 and AgNPs as a High-Performance Aptasensing Platform in Staphylococcus aureus Detection.

This study reports the synthesis of a nanocomposite consisting of spongin and its applicability in the development of an aptasensing platform with high performance. The spongin was carefully extracted from a marine sponge and decorated with copper tungsten oxide hydroxide. The resulting spongin-copper tungsten oxide hydroxide was functionalized by silver nanoparticles and utilized in electrochemical aptasensor fabrication. The nanocomposite covered on a glassy carbon electrode surface amplified the electron transfer and increased active electrochemical sites. The aptasensor was fabricated by loading of thiolated aptamer on the embedded surface via thiol-AgNPs linkage. The applicability of the aptasensor was tested in detecting the Staphylococcus aureus bacterium as one of the five most common causes of nosocomial infectious diseases. The aptasensor measured S. aureus under a linear concentration range of 10-108 colony-forming units per milliliter and a limit of quantification and detection of 12 and 1 colony-forming unit per milliliter, respectively. The highly selective diagnosis of S. aureus in the presence of some common bacterial strains was satisfactorily evaluated. The acceptable results of the human serum analysis as the real sample may be promising in the bacteria tracking in clinical samples underlying the green chemistry principle.

Immunodiagnostic of Vibrio cholerae O1 using localized surface plasmon resonance (LSPR) biosensor.

V. cholerae O1 is a gram-negative bacilli that causes an acute gastrointestinal disease called cholera. V. cholerae can enter into the biofilm phase in a period of life; hence, it is challenging to recognize these bacteria. Accordingly, using localized surface plasmon resonance (LSPR) features of the nanoparticles, an accurate detection method based on the antigen-antibody reaction was used. Ordinarily, immobilization of plasmonic nanoparticles by monoclonal antibodies was performed and UV-visible spectroscopy, dynamic light scattering (DLS), and zeta potential (Zp) measurements verified the conjugation process. In the vicinity of several concentrations of V. cholerae O1, the consistency of the engineered nanobioprobe was then investigated using LSPR monitoring and colorimetric assay. Finally, the ELISA and PCR techniques contrasted the sensitivity of nanobiosensors. The results showed that by applying monoclonal antibodies as a sensor feature, the nanobioprobe showed high sensitivity to target bacterial analysis. Thus, the limit of detection in this immunoassay-based biosensor was calculated to be a sharp reduction in the absorption of 10 CFU/mL of V. cholerae O1 with approximately 5 nm of redshift, while the shift of light refraction in the LSPR band was extended to approximately 18 nm by raising the antigen concentration to 104 CFU/mL. This LSPR biosensor can therefore be used for V. cholerae O1 (Inaba strain) detection as a simple, sensitive, and reliable diagnostic tool. In conclusion, the built biosensor will facilitate and speed up V. cholerae O1 (Inaba strain) classification by controlling the specific antigen to prevent the unintended spread of cholera disease.