Gayani Pathiraja

It is necessary to develop a sensitive and selective analytical method for detecting organophosphate insecticides, such as malathion, for environmental protection. Herein, we have designed an innovative sensing platform that incorporates silver nanoparticles (AgNPs) into molecularly imprinted polymers (MIPs), with AgNPs synthesized via in situ silver ion reduction during the precipitation polymerization of the MIP. Integrating AgNPs into MIP allows us to leverage both the selectivity and high sensitivity of molecular imprinting technology and the enhanced surface-enhanced Raman scattering (SERS) properties of AgNPs. The sensors demonstrate a linear detection range of 0.005-5 µg/ml and a limit of detection (LOD) of 0.005 µg/ml for malathion in water solution. The sensor is tested and evaluated in spiked drinking and tap water, obtaining recovery rates ranging from 93% to 100.5%. The AgNPs@MIP SERS sensor provides a rapid, selective, and sensitive approach for malathion detection, promising to develop an analytical tool for environmental and agricultural monitoring of organophosphate compounds.

The design of effective nanocomposites offers a solution by enhancing the selectivity and differentiation of phosphates.

Developing efficient, thermally resistant, and fire‐retardant materials requires innovative approaches to modulate the mean free path of air for thermal transport in insulators. Herein, an inorganic silica NPs@Mg‐Al LDH nanocomposite is designed, which synergizes the lateral interactions of monodisperse, hydrophilic silica nanoparticles (NPs) and layered double hydroxides (LDH) nanoflake lamella structure. Upon heating to 550°C, the nanocomposite composed of LDH and silica with a weight ratio of 1:3 (LDH1Si3) exhibits a remarkably higher thermally stable structure, outperforming its counterparts in terms of their structural rigidity. Advanced characterization techniques, including microscopy (TEM, SEM, and STEM/EDX), spectroscopy, and thermal analysis, reveal that the effective integration of 3D network structures without phase segregation enhances heat transport by utilizing voids, gaps, and holes, resulting in minimal structural loss at high temperatures. The silica NPs serve as the dominant thermally stable active sites, concurrently MgAl‐LDH introduces improved thermal resistance with interfacial Si─O─M (M = Mg, Al) bonding. This work unveils a facile, cost‐effective, and non‐toxic nanomaterial that can be designed as a high‐temperature insulating coating for fabrics.

An innovative biosorbent-based water remediation unit could reduce the demand for freshwater while protecting the surface and groundwater sources by using saline water resources, such as brine, brackish water, and seawater for irrigation. Herein, for the first time, we introduce a simple, rapid, and cost-effective iron(III)-tannate biosorbent-based technology, which functions as a stand-alone fixed-bed filter system for the treatment of salinity, heavy-metal contaminants, and pathogens present in a variety of water resources. Our approach presents a streamlined, cost-efficient, energy-saving, and sustainable avenue for water treatment, distinct from current adsorption desalination or conventional membrane techniques supplemented with chemical and UV treatments for disinfection. The proof of feasibility for effective treatment of heavy metals, adsorption desalination, and cleansing of pathogens is demonstrated using synthetic water, brine, and field-collected seawater. The adsorption equilibrium and adsorption kinetic isotherm models, and mass transfer diffusion models confirmed the sorbent's function for sieving heavy-metal ions-silver (Ag⁺), cadmium (Cd²⁺), and lead (Pb²⁺)-from water. The maximum adsorption capacities (q _m) of the sorbent for Ag⁺, Cd²⁺, and Pb²⁺ reach 96.25, 66.54, and 133.83 mg/g at neutral pH. The sorbent's affinity for heavy-metal-ion adsorption significantly increased, yielding q _m of 116.57 mg/g for Ag⁺, 104.04 mg/g for Cd²⁺, and 165.66 mg/g for Pb²⁺, at pH 9, respectively, due to the sorbent's amphoteric nature. The pristine sorbents exhibit exceptional adsorption desalination efficacy (>70%) for removing salinity from brine and seawater, promoting heterogeneous adsorption. Fe(III)-TA's ability to disinfect seawater, with 67% efficacy over a very short contact time (∼15 min), confirms its remarkable antimicrobial properties for contact active mode pathogens cleansing. By preventing the release of salts, heavy-metal contaminants, and pathogens into the environment, our results proved that this novel multiplex biobased sorbent approach directly contributes to the water quality of surface and groundwater resources.

Isoreticularity in metal organic frameworks (MOFs) allows the design of the framework structure and tailoring the pore aperture at the molecular level. The optimal pore volume, long-range order of framework expansion, and crystallite size (grain size) could enable improving Li-ion conduction, thereby providing a unique opportunity to design high-performance solid and quasi-solid electrolytes. However, definitive understanding of the pore aperture, framework expansion, and crystallite size on the Li-ion conduction and its mechanism in MOFs remains at the exploratory stage. Among the different MOF subfamilies, Li-MOFs created by the isoreticular framework expansion using dicarboxylates of benzene, naphthalene, and biphenyl building blocks emerge as low-density porous solids with exceptional thermal stability to study the solid-state Li⁺ transport mechanisms. Herein, we report the subtle effect of the isoreticularity in Li-MOFs on the performance of solid and quasi-solid-state Li⁺ conduction, providing new insight into Li⁺ transport mechanisms in MOFs for the first time. Our experimental and computational results show that the reticular design on an isostructural extended framework structure with the optimal pore aperture and crystallite size can influence the Li⁺ conductivity, exhibiting comparable ionic conductivities to solid polymer electrolytes at room temperature. Aligning with the computational studies, our experimental absorption spectral traces of solid electrolytes prepared by encapsulating lithium salt (LiClO₄) and the plasticizer (ethylene carbonate) with Li-MOFs confirm the participation of the free and bound states of Li⁺ in a pore filling-driven ion conduction mechanism. We postulate that porous channels of Li-MOFs aid free Li⁺ to move through the pores via a vehicle-type mechanism, in which the pore-filled plasticizer acts as a carrier for mobile Li⁺ while the framework's functional sites transport the bound state of Li⁺ via an ion hopping mechanism from one crystallite site to another. Our computational studies performed on the Li⁺ conduction pathway validated the postulated pore filling mechanism and confirmed the involvement of bridging complexes, formed by binding Li⁺ onto the framework's functional sites as well as to the pore-filled ethylene carbonates. The Li⁺ diffusion energy barrier profiles along with the respective conformational changes during the diffusion of Li⁺ in solid electrolytes prepared from Li-BDC MOF and Li-NDC MOF strongly support the cooperative movement of Li⁺ ions via ion hopping along the framework's edges and vehicle-type transfer, involving the pore-filled plasticizer. Our findings suggest that cooperative function of the optimal pore volume, framework expansion, and crystallite size play a unique role in Li-ion conduction, thereby providing design guidelines for the low-density solid and quasi-solid electrolytes.

Developing a biomolecular detection method that minimizes photodamage while preserving an environment suitable for biological constituents to maintain their physiological state is expected to drive new diagnostic and mechanistic breakthroughs. In addition, ultra-sensitive diagnostic platforms are needed for rapid and point-of-care technologies for various diseases. Considering this, surface-enhanced Raman scattering (SERS) is proposed as a non-destructive and sensitive approach to address the limitations of fluorescence, electrochemical, and other optical detection techniques. However, to advance the applications of SERS, novel approaches that can enhance the signal of substrate materials are needed to improve reproducibility and costs associated with manufacture and scale-up. Due to their physical properties and synthesis, semiconductor-based nanostructures have gained increasing recognition as SERS substrates; however, low signal enhancements have offset their widespread adoption. To address this limitation and assess the potential for use in biological applications, zinc oxide (ZnO) was coated with different concentrations (0.01–0.1 M) of gold (Au) precursor. When crystal violet (CV) was used as a model target with the synthesized substrates, the highest enhancement was obtained with ZnO coated with 0.05 M Au precursor. This substrate was subsequently applied to differentiate exosomes derived from three cell types to provide insight into their molecular diversity. We anticipate this work will serve as a platform for colloidal hybrid SERS substrates in future bio-sensing applications.

Developing a biomolecular detection method that minimizes photodamage while maintaining an environment suitable for biological constituents to maintain their physiological state is expected to drive new diagnostic and mechanistic breakthroughs. In addition, ultra-sensitive diagnostic platforms are needed for rapid and point-of-care technologies for various diseases. Considering this, surface-enhanced Raman scattering (SERS) is proposed as a non-destructive and sensitive approach to address the limitations of fluorescence, electrochemical, and other optical detection techniques. However, to advance the applications of SERS, novel approaches to enhance the signal of substrate materials are needed to improve reproducibility and costs associated with manu-facture and scale-up. Due to their physical properties and synthesis, semiconductor-based nanostructures have gained increasing recognition as SERS substrates; however, low signal en-hancements have offset their widespread adoption. To address this limitation and assess the po-tential for use in biological applications, zinc oxide (ZnO) was coated with different concentra-tions (0.01-0.1 M) of gold (Au) precursor. When crystal violet (CV) was used as a model target with the synthesized substrates, the highest enhancement was obtained with ZnO coated with 0.05 M Au precursor. This substrate was subsequently applied to differentiate exosomes derived from three cell types to provide insight into their molecular diversity. We anticipate this work will serve as a platform for colloidal hybrid SERS substrates in future bio-sensing applications.