Applied Nanoscience最新文献

Schiff base compounds were reported to make a complex with Cu²⁺ and Ag⁺ and subsequent reduction produced Cu⁰ and Ag⁰ nanoparticles separately via UV irradiation. Here, we synthesized a Schiff base, which initially formed a complexation with Cu²⁺ and made Cu⁰ nanoparticles after 8 h aging. In that reaction mixture, addition of Ag⁺ resulted in Ag⁰ nanoparticles. Emissive semi-carbazone (a Schiff base synthesized from semicarbazide and salicylaldehyde) was employed for the first time to selectively and sensitively detect Cu²⁺ (linear range of detection 10^–4 to 5 × 10^–8 M and limit of detection 13 μM) with the formation of copper oxide nanoparticles via complexation–reduction method. The introduction of Ag⁺ in it produced Ag⁰ and Cu⁰ (CuO via aerial oxidation) nanoparticles with a gigantic increase of fluorescence to obtain selective and sensitive Ag⁺ detection (linear detection range 10^–3–10^–7 M, and limit of detection 7. 7 μM). Thus, Cu²⁺ and Ag⁺ were detected based on turn-off/on fluorescence in one pot. As the evolution of copper and silver nanoparticles was the fundamental reason for sensing, response time is similar to the stable fluorescence behavior of oxidized SC (capping agent) with in situ generated copper and silver nanoparticles. CuO-induced fluorescence quenching was due to the formation of the trapped plasmon, while Ag⁺-induced fluorescence enhancement was owing to the lightning rod effect. The synergism of Cu and Ag was also investigated in this paper as a driving force of the lightning rod effect for the first time. Both the metals (Cu and Ag) were estimated in natural water, justifying the utility of the sensing platform for practical applications. Besides, the evolution of brilliant red color with semi-carbazone for Ag⁺ was employed for the colorimetric sensing of Ag⁺.

Green-synthesized nitrogen-doped carbon quantum dots (N-CQDs), offering an excellent platform for the ultra-sensitive dual detection of tannic acid and Hg²⁺ ions, were explored in this work. The N-CQDs were synthesized in a straightforward, cost-effective, and environmentally friendly hydrothermal method. These N-CQDs exhibited remarkable and dynamic “on-off-on” luminescent characteristics, demonstrating an exceptional sensitivity and selectivity towards tannic acid and Hg²⁺ ions. The specific interactions between the N-CQDs and tannic acid, along with the reversible binding with Hg²⁺ ions, contribute to the distinct dual-detection capabilities. The sensing system covers a linear concentration range of 10–80 µM to tannic acid and 0.1 to 1 nm for Hg²⁺, showcasing its versatility for different concentration range with a lower detection limit of 25 nM and 3 nM, respectively. Furthermore, the N-CQDs displayed high stability and minimal interference from typical interfering species, making them a desirable tool for environmental monitoring and quality control. Validation through real sample analysis substantiates the accuracy and reliability of the developed sensing approach in practical scenarios. This study not only underscores the promise of green-synthesized N-CQDs as enhanced fluorescence probes but also contributes to the development of efficient and environmentally friendly materials for dual sensing applications.

Increasing mechanical properties without losing electrical properties is of great importance for the development of advanced electronic textile products and their use in different areas. In this study, a cost-effective and facile preparation of MXene/cellulose nanocrystal-coated cotton fabrics by drop-casting was carried out to investigate electrical and mechanical properties of plain woven cotton fabrics. MXene (Ti₃C₂T_x) and cellulose nanocrystal dispersions of MXene (5 wt.%, 10 wt.% and 15 wt.% cellulose nanocrystal content) were applied to cotton fabrics, and the coated fabrics were characterized in terms of their morphological and structural properties for their suitability for wearable electronics. The surface resistivity and mechanical properties were also determined to evaluate the effectiveness of coating. Ti₃C₂T_x/cellulose nanocrystal dispersions are suitable to obtain a low electrical resistivity (186.4 Ω/sq) in cotton fabrics. The results also showed that increasing cellulose nanocrystal content results in a more stable coating layer on the cotton fabric and a high tensile (63.2 MPa) and elongation at break values are obtained (30.2%) as a result of that.

In third-world countries, the biosynthesis of multi-purpose copper oxide nanoparticles is a crucial solution for pollution, but studies on controlling their properties through internal structure are still limited. This work generated copper oxide nanoparticles (CONPs) using bee propolis as a reducing and capping agent, employing an ecologically benign, simple, inexpensive, and economical technique. The pH of this biosynthesis was varied (6.4, 7.8, 9.2, 10.4, and 11.7). The study computed various structural and optical parameters of biosynthesized CONP samples, revealing nonlinear changes with pH, including unit cell, Cu–O bond length, crystal size, microstrain, energy band gap, Urbach energy, and more. The current research has shown promising results in blocking ultraviolet rays effectively. The blocking parameters were calculated for CONPs samples, and it was found that the pH 8 sample had the best blocking capacity at both regions A and B (90.31 and 91.31%, respectively). The study effectively investigated CONPs’ potential as a catalyst for increasing dye photodegradation. The pH 6.4 sample showed the highest degradation rate (94.15%). The UV-blocking and photodegradation properties of the CONPs samples were explained using the structural and optical parameters.

In the ever-evolving field of medical diagnostics and imaging, the development of efficient and versatile contrast agents remains pivotal. This study presents a pioneering approach to synthesize superparamagnetic magnetite nanoparticles (SM-NPs) derived from natural ore using an environmentally friendly, green chemistry approach. These SM-NPs exhibit exceptional magnetic properties, surpassing all other forms of iron oxide, making them a novel and promising multi-imaging agent for various biomedical applications. The SM-NPs were synthesized with high purity from naturally occurring magnetite, sourced from the Earth's crust. Characterization via X-ray diffraction (XRD) confirmed the cubic spinel ferrites structure of the sample, with an average particle size of 21.24 nm. Fourier-Transform Infrared Spectroscopy (FT-IR) revealed the presence of elemental functional groups, further supporting the material's suitability for biomedical use. Morphological analysis using field emission scanning electron microscopy with energy-dispersive X-ray analysis (FESEM-EDX) unveiled agglomerated spherical particles ranging in size from 60 to 80 nm. The elemental composition analysis via EDX demonstrated predominant iron (Fe) and oxygen (O) elements at concentrations of 75.55% and 20.76%, respectively. The magnetic properties of the SMNPs were assessed using a vibrating sample magnetometer (VSM), revealing a superparamagnetic behavior, as evidenced by the M-H plot. Furthermore, X-ray imaging exhibited a significant signal, even with just 40 mg of the substance, suggesting its potential as a robust contrast agent. Complementary findings from computed tomography (CT) and magnetic resonance imaging (MRI) scans demonstrated substantial absorption capabilities, even at relatively low concentrations of SM-NPs. These remarkable attributes position the green-synthesized SM-NPs as a highly versatile and efficient multi-imaging agent for various biomedical applications. This single nanomaterial can revolutionize disease diagnosis, treatment monitoring, and drug delivery within the biomedical field, offering a greener and more effective approach to medical imaging and diagnostics.

The requirement for passive thermal regulation in portable electronic devices enabled by 5G has escalated due to the significant heat produced during the operation of devices, resulting in a detrimental rise in human body temperature and reduced device longevity. This article explores various materials, such as hydrogels, metal–organic frameworks (MOFs), and phase-change materials (PCMs), which utilize natural convection and radiation to dissipate heat from the device, and their potential challenges and solutions for improvement. Hydrogels are not an optimal material due to their lack of cyclic stability and limited water adsorption capability, while MOFs are expensive and PCMs struggle with internal leakage during the solid-to-liquid transition. Thus, insights into novel hybrid materials and their potential for thermal resistance have been discussed. The study considers material marketing and sustainability. To enhance material performance, early-stage inclusion of recyclable, biomass-derived, or environmentally beneficial materials is recommended. Addressing the heat issue in 5G-enabled portable electronics, the article introduces practical passive thermal management materials.

The antibacterial properties of cicada wings originate from hexagonally arranged pillar-like multi-functional nanostructures with species-dependent heights, which are super-hydrophobic and self-cleaning. In the present study, two cicada species with promising nanopillars were investigated in more detail. Selected methods were used to analyze the wing surfaces, including Atomic Force Microscopy, Scanning Electron Microscopy, and bacterial tests with live/dead staining. Verifying the antibacterial properties posed challenges, such as the bacteria concentration needed to confirm the antibacterial properties. These challenges will also impact the practical implementation of antibacterial nanostructures and support the findings of recent critical publications.

The present study investigates the synthesis of vertically aligned MnO₂ nanowires (NW) decorated with gold (Au) and silver (Ag) nanoparticles (NP) via the glancing angle deposition (GLAD) technique without a need for a catalyst. The cross-sectional field emission scanning electron microscopy (FESEM) image and energy-dispersive X-ray spectroscopy (EDS) confirm the successful adornment of Ag NP and Au NP on the top surface of MnO₂ NW. Elemental mapping has verified the presence of manganese (Mn), oxygen (O), silicon (Si), Ag, and Au within the sample. X-ray diffraction (XRD) patterns reveal the polycrystalline growth of the MnO₂ film with the preferred orientation. AFM reveals that the surface roughness of Au NP/MnO₂ NW is more than Ag NP/MnO₂ NW. The measured water contact angles of Au NP/MnO₂ NW, Ag NP/MnO₂ NW, and MnO₂ NW were 125° and 113°, respectively. Ag NP/MnO₂ NW showed more hydrophilic properties under UV illumination than Au NP/MnO₂ NW owing to the efficient separation of photogenerated electron–hole pairs. Ag NP/MnO₂ NW’s higher photocatalytic activity than Au NP/MnO₂ NW is attributed to the increased light absorption of the Ag NP in the UV region. The overall enhancement after decorating the noble metal NP on MnO₂ NW could open new avenues for self-cleaning applications.

Copper nanoparticles (CuNPs) have drawn considerable interest because of recent evidences on greater Surface Enhanced Raman Spectroscopic (SERS) signal enhancing capability, high antibacterial activity and strong catalytic property with regard to the long existing popular silver and gold particles. The existing chemical synthesis methods usually require extensive purification to remove unreacted inorganic reducing agents, like sodium borohydride used to convert Cu²⁺ ions to Cu⁰ and it limits direct use of as-prepared materials in biologic systems. Here, we have endeavored to synthesize starch encapsulated CuNPs through radiation chemical approach which is considered to be one of the cleanest routes and involve in-situ generated hydrated electrons to reduce metal ions directly. Presence of large number of hydroxyl groups within starch molecules facilitates complexation of Cu(II) and thereby stabilizes CuNPs. Transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) illustrate that particles synthesized at a typical dose of 83.6 kGy are spherical with size of ca. 8 nm having polycrystalline face-centered cubic phase. The observed blue shift of the absorption maximum suggests formation of smaller sized particles with increase in applied radiation dose keeping other parameters same and this is supported by dynamic light scattering (DLS) data. Further, catalytic efficiency of as-synthesized CuNPs was tested by monitoring sodium borohydride mediated catalytic reduction of para-nitrophenol to para-aminophenol and the apparent rate constant (k_app) was estimated as 3 × 10^–3 s⁻¹. Thus, as-synthesized CuNPs appears to be better catalyst than the copper nanoparticles synthesized through conventional method for having k_app of about 1.6 × 10^–3 s⁻¹.

Nanozymes, possessing enzyme-like traits, have gained tremendous attention for their functionality, ease of production, economical synthesis, and stability. Majority of reported nanozymes in literature, for analyte detection are metal-based compounds, transition metal dichalcogenides or single-atom nanozymes. In this study, we report for the first time, a novel peroxidase-mimic, colloidal dendritic nanozyme from lignin-rich agro-industrial residue (coconut husk) by ozonolysis. Synthesized nanozyme exhibited peroxidase-mimic activity in sensing H₂O₂, with a wide range of substrates and detection techniques. When 3,3′,5,5′-tetramethylbenzidine (TMB) and 2′,7′–dichlorofluorescin diacetate (DCFDA) were used, the nanozyme demonstrated ultrafast kinetic behaviour with LOD of 43.60 ± 2.41 µM and 1.25 ± 0.31 µM H₂O₂, by colorimetric and fluorimetric assays, respectively. The nanozyme-based H₂O₂ sensing platform, was further utilized for detection of pathogenic bacteria namely Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Pseudomonas aeruginosa, and for total bacterial load in water. Notably, it demonstrated high sensitivity in the detection of P. aeruginosa with LOD as low as 7 CFU/mL with both fluorimetric and electrochemical methods. Ultrasensitive detection of total bacterial load could also be achieved with 5.5 × 10² CFU/mL, 5.5 × 10¹ CFU/mL, and 4.1 × 10¹ CFU/mL by colorimetric, fluorometric, and electrochemical techniques, respectively. Results of the study thus indicate, that the developed nanozyme-based sensing platform had high sensitivity for detection of bacteria as well as versatility with diverse analytical approaches enabling potential practical application for “onsite” monitoring of water quality, especially in rural settings. This biological mimic can also be used in sensor platforms where H₂O₂ is measured and applied for output signaling.