Computational Study of APTES Surface Functionalization of Diatom-like Amorphous SiO2 Surfaces for Heavy Metal Adsorption

Pulsed Airstream-Driven Hierarchical Micro-Nano Pore Structured Triboelectric Nanogenerator for Wireless Self-Powered Formaldehyde Sensing

Formaldehyde (HCHO), as a common volatile organic compound, has a serious impact on human health in the daily lives and industrial production scenarios. Given the security issue of HCHO detection and danger warning, a ZIF-8/copper foam based pulsed airstream-driven triboelectric nanogenerator (ZCP-TENG) is designed to develop the self-powered HCHO sensors. By combining contact electrification and electrostatic induction, the ZCP-TENG can be utilized for airflow energy harvesting and HCHO concentration detection. The short-circuit current and output power of the ZCP-TENG can reach 2.0 µA and 81 µW (20 ppm). With the high surface area, abundant micro-nano pores, and excellent permeation flux, the ZCP-TENGs exhibit excellent HCHO sensing response (61.3% at 100 ppm), low detection limit (≈2 ppm), and rapid response/recovery time (14/15 s), which can be served as a highly sensitive and selective HCHO sensor. By connecting an intelligent wireless alarm, the ZCP-TENGs are designed to construct a self-powered warning system to monitor and remind the HCHO of exceedance situations. Moreover, by combining a support vector machine model, the difference concentrations can be quickly identified with an average prediction accuracy of 100%. This study illustrates that ZCP-TENGs have broad application prospects and provide guidance for HCHO monitoring and danger warnings.

Synergistic effects of copper and oxygen vacancies in enhancing the efficacy of partially crystalline CuMnxOy catalyst for ozone decomposition

To tackle the challenge of ground-level ozone pollution, this study proposed a potential catalytic design approach for ozone decomposition using Cu-Mn bimetallic oxide. This approach is grounded in an understanding of the intrinsic reactivity for catalyst and incorporates a novel potassium-driven low-temperature oxidation process for catalyst synthesis. The research highlights the creation of a highly reactive Cu-Mn oxide phase with extensive defect coverage, leading to significantly increased reaction rates. It also identifies the MnO2(100) facet as a crucial active phase, where oxygen vacancies simultaneously enhance O3 adsorption and decomposition, albeit with a concurrent risk of O2 poisoning due to the stabilization of adsorbed O2. Crucially, the incorporation of Cu offsets the effects of oxygen vacancies, influencing conversion rates and lessening O2 poisoning. The synergistic interplay between Cu and oxygen vacancies elevates the performance of the defect-rich Cu-Mn oxide catalyst. By combining computational and experimental methods, this study not only advances the understanding of the Cu-Mn oxide system for ozone decomposition but also contributes valuable insights into developing more efficient catalysts to mitigate ozone pollution.

Microalgae derived honeycomb structured mesoporous diatom biosilica for adsorption of malachite green: Process optimization and modeling

The present study investigated the removal of malachite green dye from aquifers by means of microalgae-derived mesoporous diatom biosilica. The various process variables (dye concentration, pH, and adsorbent dose) influencing the removal of the dye were optimized and their interactive effects on the removal efficiency were explored by response surface methodology. The pH of the solution (pH = 5.26) was found to be the most dominating among other tested variables. The Langmuir isotherm (R2 = 0.995) best fitted the equilibrium adsorption data with an adsorption capacity of 40.7 mg/g at 323 K and pseudo-second-order model (R2 = 0.983) best elucidated the rate of dye removal (10.6 mg/g). The underlying mechanism of adsorption was investigated by Weber-Morris and Boyd models and results revealed that the film diffusion governed the overall adsorption process. The theoretical investigations on the dye structure using DFT-based chemical reactivity descriptors indicated that malachite green cations are electrophilic, reactive and possess the ability to accept electrons, and are strongly adsorbed on the surface of diatom biosilica. Also, the Fukui function analysis proposed the favorable adsorption sites available on the adsorbent surface.

Reactive Simulations of Silica Functionalization with Aromatic Hydrocarbons

Reactive molecular dynamics simulations are used to model the covalent functionalization of amorphous silica with aromatic hydrocarbons. Simulations show that the surface density of silanol-terminated phenyl, naphthyl, and anthracenyl molecules is lower than the maximum value calculated based on molecule geometry, and the simulation densities decrease faster with the number of aromatic rings than the geometric densities. The trends are analyzed in terms of the surface-silanol bonding configurations, tilt angles, local conformational ordering, and aggregation of surface-bound molecules under steady-state conditions. Results show that the surface density is affected by both the size and symmetry of the aromatic hydrocarbons. The correlations among bonding, orientation, and surface density identified here may guide the selection or design of molecules for functionalized surfaces.

Acceleration of Diels-Alder reactions by mechanical distortion

Challenges in quantifying how force affects bond formation have hindered the widespread adoption of mechanochemistry. We used parallel tip-based methods to determine reaction rates, activation energies, and activation volumes of force-accelerated [4+2] Diels-Alder cycloadditions between surface-immobilized anthracene and four dienophiles that differ in electronic and steric demand. The rate dependences on pressure were unexpectedly strong, and substantial differences were observed between the dienophiles. Multiscale modeling demonstrated that in proximity to a surface, mechanochemical trajectories ensued that were distinct from those observed solvothermally or under hydrostatic pressure. These results provide a framework for anticipating how experimental geometry, molecular confinement, and directed force contribute to mechanochemical kinetics.

Generation of zinc ion-rich surface via in situ growth of ZIF-8 particle: Microorganism immobilization onto fabric surface for prohibit hospital-acquired infection

Viruses/bacteria outbreaks have motivated us to develop a fabric that will inhibit their transmission with high potency and long-term stability. By creating a metal-ion-rich surface onto polyester (PET) fabric, a method is found to inhibit hospital-acquired infections by immobilizing microorganisms on its surface. ZIF-8 and APTES are utilized to overcome the limitations associated with non-uniform distribution, weak biomolecule interaction, and ion leaching on surfaces. Modified surfaces employing APTES enhance ZIF-8 nucleation by generating a monolayer of self-assembled amine molecules. An in-situ growth approach is then used to produce evenly distributed ZIF-8 throughout it. In comparison with pristine fabric, this large amount of zinc obtained from the modification of the fabric has a higher affinity for interacting with membranes of microorganisms, leading to a 4.55-fold increase in coronavirus spike-glycoprotein immobilization. A series of binding ability stability tests on the surface demonstrate high efficiency of immobilization, >90%, of viruses and model proteins. The immobilization capacity of the modification fabric stayed unchanged after durability testing, demonstrating its durability and stability. It has also been found that this fabric surface modification approach has maintained air/vapor transmittance and air permeability levels comparable to pristine fabrics. These results strongly advocate this developed fabric has the potential for use as an outer layer of face masks or as a medical gown to prevent hospital-acquired infections.

Biomimetic Chip Enhanced Time-Gated Luminescent CRISPR-Cas12a Biosensors under Functional DNA Regulation

Despite that the currently discovered CRISPR-Cas12a system is beneficial for improving the detection accuracy and design flexibility of luminescent biosensors, there are still challenges to extend target species and strengthen adaptability in complicated biological media. To conquer these obstacles, we present here some useful strategies. For the former, the limitation to nucleic acids assay is broken through by introducing a simple functional DNA regulation pathway to activate the unique trans-cleavage effect of this CRISPR system, under which the expected biosensors are capable of effectively transducing a protein (employing dual aptamers) and a metal ion (employing DNAzyme). For the latter, a time-gated luminescence resonance energy transfer imaging manner using a long-persistent nanophosphor as the energy donor is performed to completely eliminate the background interference and a nature-inspired biomimetic periodic chip constructed by photonic crystals is further combined to enhance the persistent luminescence. In line with the above efforts, the improved CRISPR-Cas12a luminescent biosensor not only exhibits a sound analysis performance toward the model targets (carcinoembryonic antigen and Na⁺) but also owns a strong anti-interference feature to actualize accurate sensing in human plasma samples, offering a new and applicative analytical tool for laboratory medicine.

Assessing the influence of pore structure formation on heavy metal immobilization through image-based CFD

Porous media are widely adopted as immobilization sorbents in environmental engineering. The microscale difference in pore structure formation causes significant deflection in a vast landscape. Computational fluid dynamics (CFD) offers a comparative approach to evaluate the individual influence from pore structure formation with strictly controlled surface and volume properties. This paper presents a comprehensive comparison between the performance of cylindrical media and spherical-media in heavy metal immobilization. Digital testing was performed to measure the surface area, specific surface area, density and porosity. Image-based input technique was developed to reconstruct the cylindrical media. It was found that although the surface area, specific surface area and porosity were the same, the spherical media still had an accelerated immobilization rate. Results further showed that the spherical media in floatation arrangement had an immobilization rate of 16% higher than the cylindrical media with the same surface properties. Non-floatation arrangement of the spherical media caused a reduction in immobilization capacity up to 32.8% lower than the cylindrical media. The cylindrical media demonstrated an advantage of being structurally stable under high porosity, the latter of which resulted in an increased immobilization capacity compared with the spherical-media. The results suggest that the cylindrical bio-microstructure is desirable for heavy metal immobilization in a non-flotational environment. The computational approach provides a digital solution to evaluate the immobilization in 3D architected media. The proposed testing methods are feasible for both experimentally obtained images and structures from algorithm-generation.

Diatoms with Invaluable Applications in Nanotechnology, Biotechnology, and Biomedicine: Recent Advances

Diatoms are unicellular microalga found in soil and almost every aquatic environment (marine and fresh water). Biogenic silica and diatoms are attractive for biotechnological and industrial applications, especially in the field of biomedicine, industrial/synthetic manufacturing processes, and biomedical/pharmaceutical sciences. Deposition of silica by diatoms allows them to create micro- or nanoscale structures which may be utilized in nanomedicine and especially in drug/gene delivery. Diatoms with their unique architectures, good thermal stability, suitable surface area, simple chemical functionalization/modification procedures, ease of genetic manipulations, optical/photonic characteristics, mechanical resistance, and eco-friendliness, can be utilized as smart delivery platforms. The micro- to nanoscale properties of the diatom frustules have garnered a great deal of attention for their application in diverse areas of nanotechnology and biotechnology, such as bioimaging/biosensing, biosensors, drug/gene delivery, photodynamic therapy, microfluidics, biophotonics, solar cells, and molecular filtrations. Additionally, the genetically engineered diatom microalgae-derived nanoporous biosilica have enabled the targeted anticancer drug delivery to neuroblastoma and B-lymphoma cells as well as the mouse xenograft model of neuroblastoma. In this perspective, current trends and recent advances related to the applications of diatoms for the synthesis of nanoparticles, gene/drug delivery, biosensing determinations, biofuel production, and remediation of heavy metals are deliberated, including the underlying significant challenges and future perspectives.

Mixed Oxide Layered Double Hydroxide Materials: Synthesis, Characterization and Efficient Application for Mn2+ Removal from Synthetic Wastewater

Magnesium–aluminum (Mg-Al) and magnesium–aluminum–nickel (Mg-Al-Ni) layered double hydroxides (LDHs) were synthesized by the co-precipitation method. The adsorption process of Mn²⁺ from synthetic wastewater was investigated. Formation of the layered double hydroxides and adsorption of Mn²⁺ on both Mg-Al and Mg-Ni-Al LDHs were observed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDX) analysis. XRD patterns for prepared LDHs presented sharp and symmetrical peaks. SEM studies revealed that Mg-Al LDH and Mg-Al-Ni LDH exhibit a non-porous structure. EDX analysis showed that the prepared LDHs present uniformly spread elements. The adsorption equilibrium on these LDHs was investigated at different experimental conditions such as: Shaking time, initial Mn²⁺ concentration, and temperatures (10 and 20 °C). The parameters were controlled and optimized to remove the Mn²⁺ from synthetic wastewater. Adsorption isotherms of Mn²⁺ were fitted by Langmuir and Freundlich models. The obtained results indicated that the isotherm data fitted better into the Freundlich model than the Langmuir model. Adsorption capacity of Mn²⁺ gradually increased with temperature. The Langmuir constant (K_L) value of Mg-Al LDH (0.9529 ± 0.007 L/mg) was higher than Mg-Al-Ni LDH (0.1819 ± 0.004 L/mg), at 20 °C. The final adsorption capacity was higher for Mg-Al LDH (91.85 ± 0.087%) in comparison with Mg-Al-Ni LDH (35.97 ± 0.093%), at 20 °C. It was found that the adsorption kinetics is best described by the pseudo-second-order model. The results indicated that LDHs can be considered as a potential material for adsorption of other metallic ions from wastewater.

Multi-Sample Preparation Assay for Isolation of Nucleic Acids Using Bio-Silica with Syringe Filters

The spin-column system for the isolation of nucleic acids (NAs) from multiple samples presents the inconvenience of repeated experimentation, time-consumption, and the risk of contamination in the process of the spin-column exchange. Herein, we propose a convenient and universal assay that can be used to diagnose multiple pathogens using a multi-sample preparation assay. The multi-sample preparation assay combines a 96-well filter/membrane plate, a bio-micromaterial lattice-like micro amine-functional diatomaceous earth (D-APDMS), and homobifunctional imidoesters (HI) for the processing of pathogen enrichment and extraction for multiple samples simultaneously. The purity and quantity of the extracted NAs from pathogens (E. coli and Brucella) using the proposed assay is superior to that of the commercialized spin-column kit. The assay also does not require the replacement of several collection tubes during the reaction processing. For the multi-sample testing, we used as many as six samples simultaneously with the proposed assay. This assay can simultaneously separate up to 96 NAs from one plate, and the use of multichannel pipettes allows faster and simpler experimentation. Therefore, we believe it is a convenient and easy process, and can be easily integrated with other detection methods for clinical diagnostics.