There is a strong commercial need for inexpensive point-of-use sensors for monitoring disease biomarkers or environmental contaminants in drinking water. Point-of-use sensors that employ smart polymer hydrogels as recognition elements can be tailored to detect almost any target analyte, but often suffer from long response times. Hence, we describe here a fabrication process that can be used to manufacture low-cost point-of-use hydrogel-based microfluidics sensors with short response times. In this process, mask-templated UV photopolymerization is used to produce arrays of smart hydrogel pillars inside sub-millimeter channels located upon microfluidics devices. When these pillars contact aqueous solutions containing a target analyte, they swell or shrink, thereby changing the resistance of the microfluidic channel to ionic current flow when a small bias voltage is applied to the system. Hence resistance measurements can be used to transduce hydrogel swelling changes into electrical signals. The only instrumentation required is a simple portable potentiostat that can be operated using a smartphone or a laptop, thus making the system suitable for point of use. Rapid hydrogel response rate is achieved by fabricating arrays of smart hydrogels that have large surface area-to-volume ratios.

The availability of clean drinking water is a significant problem worldwide. Many technologies exist for purifying drinking water, however, many of these methods require chemicals or use simple methods, such as boiling and filtering, which may or may not be effective in removing waterborne pathogens. Present methods for detecting pathogens in point-of-use (POU) sterilized water are typically time prohibitive or have limited ability differentiating between active and inactive cells. This work describes a rapid electrochemical sensor to differentially detect the presence of active Escherichia coli (E. coli) O157:H7 in samples that have been partially or completely sterilized using a new POU electrocatalytic water purification technology based on superradicals generated by defect laden titania (TiO₂) nanotubes. The sensor was also used to detect pathogens sterilized by UV-C radiation for a comparison of different modes of cell death. The sensor utilizes immunomagnetic bead separation to isolate active bacteria by forming a sandwich assay comprised of antibody functionalized secondary magnetic beads, E. coli O157:H7, and polyguanine (polyG) oligonucleotide functionalized secondary polystyrene beads as an electrochemical tag. The assay is formed by the attachment of antibodies to active receptors on the membrane of E. coli, allowing the sensor to differentially detect viable cells. Ultravioloet (UV)-C radiation and an electrocatalytic reactor (ER) with integrated defect-laden titania nanotubes were used to examine the sensors’ performance in detecting sterilized cells under different modes of cell death. Plate counts and flow cytometry were used to quantify disinfection efficacy and cell damage. It was found that the ER treatments shredded the bacteria into multiple fragments, while UV-C treatments inactivated the bacteria but left the cell membrane mostly intact.

Developing highly sensitive and selective biosensors remains a critical challenge in molecular diagnostics. A novel peptide nucleic acid (PNA)‐based biosensor platform is designed by integrating anatase‐phase titanium dioxide nanotubes (TiO₂‐NTs) with gold nanoparticles (AuNPs), deposited through sputtering and calcination to enhance signal intensity and suppress non‐specific binding. The synergistic effect arises from the high electrical conductivity of AuNPs, which reduces interfacial resistance and promotes rapid electron transfer. The anatase phase of TiO₂‐NTs further enhances charge separation, improving overall device performance. Under 50 °C hybridization conditions, the 300‐s AuNPs sputtered TiO₂‐NT electrodes demonstrate up to a 15‐fold higher complementary deoxyribonucleic acid (coDNA) signal intensity (354.75 µA cm⁻²) than bare TiO₂ electrodes, confirming robustness and improved electron transfer efficiency. Furthermore, the signal intensity of single‐stranded DNA (scDNA) decreases from 202.60 µA cm⁻² on the 60‐s AuNPs sputtered sample to 65.70 µA cm⁻² on the 300‐s sputtered sample, highlighting enhanced selectivity. This improvement is attributed to the denser AuNP distribution and enhanced electrostatic barrier formed by the electric double layer, which effectively suppresses non‐specific interactions by repelling negatively charged DNA molecules. This integration establishes a highly sensitive and selective biosensing platform with promising applications in target nucleotide diagnostics.

Titanium dioxide (TiO ₂ ) nanostructures exhibit diverse morphologies depending on synthesis conditions. This study investigates the effects of varying anodization parameters on TiO ₂ nanotubes, nanograss, and nanolace formation. Field‐emission scanning electron microscopy is employed to analyze these nanostructures’ morphology and growth rates. The structural characteristics of the resulting nanostructures are precisely controlled by adjusting temperature, water content, duration, and applied potential during the anodization process. Nanotube length and diameter are influenced by ethylene glycol (EG) concentration, applied voltage, and temperature. The quantity of nanograss is determined by the anodization temperature. Nanolace formation is affected by hydrofluoric acid (HF) pretreatment of titanium foil. The results demonstrate that higher EG concentrations and applied potentials produce longer nanotubes, whereas lower EG concentrations with higher potentials result in larger nanotube diameters. Temperature variations control the amount of nanograss. HF pretreatment facilitates the formation of a hexagonal nanolace network on the surface. By tailoring synthesis conditions, this study provides a method for controlling the morphology of TiO ₂ nanostructures. These findings have implications for optimizing TiO ₂ nanostructures in sensors, photocatalysis, and other areas of nanotechnology, where specific structural properties are crucial for enhanced performance.

3D-printed FeCo/TiO ₂ nanotube catalysts are used for the first time in Fischer–Tropsch synthesis and demonstrate considerable catalytic activity.

Cost-effectively detecting benzene, a human carcinogen, at occupationally and atmospherically relevant concentrations would benefit individuals at risk of exposure. This paper presents the development of a titania (TiO2) nanotube-based sensor array that has a high surface area, is highly sensitive, and operates at room temperature using simple, portable instrumentation. An n-type TiO2 nanotube was synthesized through electrochemical anodization in an electrolytic solution of ammonium fluoride-ethylene glycol and oxygen annealed at 500 °C for up to 8 hours. The nanotube sensor had a bandgap (Eg) of ~2.6 eV, and it was operated at a bias voltage of +1.5 V. The response of the sensor to benzene vapor was measured using an amperometric technique at room temperature, and when exposed to benzene, the sensor exhibited a decrease in current, as expected for an n-type metal oxide semiconductor. The sensor response was proportional to benzene concentration over a range of 100-400 ppb. A sensing mechanism based on Fermi level changes caused by band bending has been explained for this benzene sensor.