Green synthesis of AgNPs has gained many research interests as a low cost and eco-friendly approach. This work reported on the use of bacterial genomic DNA as the alternative biopolymer for a green production of AgNPs under a neutral pH. Although both ssDNA and dsDNA could function as stabilizing agents during the synthesis process, the ssDNA, generated by pre-heating the dsDNA at 100 °C, was more efficient to produce AgNPs with higher yield as determined by the intensity of the surface plasmon resonance (SPR) peak of silver at 475 nm. The obtained AgNPs were spherical with the average diameter of 15.0 ± 7.6 nm, which their identity was confirmed by X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction analyses. The synthesized AgNPs exhibited the potent antibacterial activity against both Escherichia coli and Staphylococcus aureus with the minimum bactericidal concentrations at 250 and 500 μg/ml, respectively, suggesting their potential antibacterial activity against both Gram-negative and Gram-positive bacteria.

Trace of 17β‐estradiol (E2) contamination in food has been a concern for its negative impacts on human health, leading to the need for an E2‐monitoring system. This work reported a new simple, sensitive, and colorimetric E2 detection based on the designed repetitive‐loop aptamer and gold nanoparticles (AuNPs). The designed aptamers (L2–L5) exhibited a higher binding capability to E2 than the original truncated aptamer (L1). Although L3–L5 aptamers exhibited the highest binding capability, only L3‐aptasensor demonstrated the sensitive detection of E2 in a range of 0.05−0.8 nM, with the limit of detection at 13.1 pM. The developed L3‐aptasensor was 7.7‐folds more sensitive for E2 detection than the L1‐aptasensor. It selectively detected E2, but not the other tested chemicals with similar structures: progesterone, genistein, diethylstilbestrol, bisphenol A, and chloramphenicol. The L3‐aptasensor efficiently detected E2 spiked in milk samples within the precision acceptance criterion of recovery rates (100.1%−113.0%) and the relative standard deviations (5.24%−11.06%). These results demonstrated the development of a new aptasensor based on the designed repetitive‐loop aptamer that could enhance E2‐detection sensitivity and be potentially used for detecting E2 in milk samples with high accuracy and reliability.

Green synthesis offers an eco-friendly and low-cost approach for the synthesis of silver nanoparticles (AgNPs). Many studies have reported on the use of biomolecules, especially plant extracts, as reducing and/or stabilizing agents in place of toxic chemicals. This study reports on the use of bacterial genomic DNA as an alternative stabilizing agent for the green synthesis of AgNPs under light activation. With both increased DNA quantities and reaction times under light exposure, more stabilized AgNPs formed as indicated by the surface plasmon resonance intensities. The synthesized AgNPs were spherical with an average size of 61.36±10.15 nm as calculated using the dynamic light scattering (DLS) technique. The X-ray diffraction, selected area electron diffraction, and high resolution transmission electron microscope (TEM) analyses confirmed the formation of face-centered cubic (fcc) structured AgNPs. The produced AgNPs exhibited antibacterial activities against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, suggesting its potential application as an antibacterial agent.

This study aims to produce electrospun cellulose acetate (CA) membrane as the alternative supporting medium for a separation of crude polysaccharides by electrophoresis and a screening of their antibacterial activity. Among the tested conditions of fabrication, electrospun CA membrane at 57% porosity showed the best separation of each polysaccharide from the standard mixture and the crude extract of via electrophoresis. As compared with the commercial CA membrane, the produced electrospun CA membrane demonstrated more separated spots of polysaccharides. The antibacterial activity of the electrophoretic polysaccharide was also determined against and as the inhibition zone after the bacterial culture agar was overlaid on the membrane and incubated for 24 h. The results of this study suggested the potential application of electrospun CA membrane combining with electrophoresis as a simple method for separating crude polysaccharides and screening for their antibacterial activity.

Several plant species survive in the metal‐contaminated environment by minimization of detrimental effects of metal exposure and cellular accumulation, but little is known about their capability to transform the uptake metal ions into nanoparticles, especially in nonspherical shapes. This work firstly reported the in vivo formation of spherical and rod‐shaped lead nanoparticles (PbNPs) from the uptake lead ions in root cells of water velvet (Azolla pinnata). The energy‐dispersive X‐ray fluorescence analysis revealed the high level of lead (67.21 ± 0.70%) and the modulated levels of sulfur, potassium, and calcium in the treated roots. Fourier‐transform infrared spectroscopy spectral analysis suggested the changes of biochemical constituents in Pb‐treated roots, including carbohydrates, organic compounds, proteins, and nucleic acids. Transmission electron microscope (TEM) images revealed the formation of spherical, short rod, and long rod PbNPs dominantly in epidermal, cortical, and vascular cells in the plant roots, respectively. The analyses of energy‐dispersive X‐ray spectroscopy, high‐resolution TEM, and selected area diffraction TEM indicated the body‐centered tetragonal lattice of lead oxide nanoparticles (PbONPs) in the root cells.