- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Xenobiotic Contamination of Water by Plastics and Pesticides Revealed Through Real-time, Ultrasensitive and Reliable Surface Enhanced Raman Scattering
摘要： Uncontrolled utilization and consequent ubiquitous percolation of carcinogenic and xenobiotic contaminants, such as plasticizers and pesticides, into ecosystem has created an immediate demand for robust analytical detection techniques to identify their presence in water. Addressing this demand, we uncover the presence of xenobiotic contaminants such as Bisphenol A (BPA), Triclosan (TC), and Dimethoate (DM) through a robust, ultrasensitive and reliable Surface Enhanced Raman Scattering (SERS) platform. Thereby, conclusive real-time evidence of degradation of polyethylene terephthalate (PET) leading to release of BPA in water is presented. Worryingly, the release of BPA occurs at ambient temperature (40 0C) and within realistic timescales (12 hours) that are regularly encountered during the handling, transport and storage of PET-based water containers. Complementary mass-spectrometric, surface-specific atomic force microscopy and surface selective X-ray Photoelectron spectroscopy confirms the nanoscale surface degradation of PET through loss of C=O and C-O surface functionalities. Such ultra-sensitive (ppm-level), spectroscopic detection is enabled by the bottom-up assemblies of metal nanoparticles (Soret Colloids, SCs) acting as SERS platform to provide high analytical enhancement factor (108) with high reliability (relative standard deviation, RSD <5%). Effective and rapid detection (30 s) of several other potential xenobiotic contaminants such as Triclosan (TC) and Dimethoate (DM) over a wide range of concentrations (10-5 to 10-1 M) has also been demonstrated. Finally, non-destructive real-time spectroscopic “sniffing” of organophosphorous pesticides from the surface of fruits is achieved, illustrating the multi-phasic versatility of this label-free, non-lithography-based SERS platform.
关键词： plastic degradation,Soret colloids,water and food contamination,real-time detection,nanoparticle assembly,surface enhanced Raman scattering,Xenobiotics
更新于2025-09-23 15:21:01
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Assembly of Conductive Polyaniline Microstructures by a Laser-Induced Microbubble
摘要： Micro-patterns of conductive polymers are key for various applications in the fields of flexible electronics and sensing. A bottom-up method that allows high-resolution printing without additives is still lacking. Here, such a method is presented based on micro-printing by the laser-induced microbubble technique (LIMBT). Continuous micro-patterning of polyaniline (PANI) was achieved from a dispersion of the Emeraldine base form of PANI (EB-PANI) in n-methyl-2-pyrrolidone (NMP). A focused laser beam is absorbed by the EB-PANI nanoparticles and leads to formation of a microbubble, followed by convection currents, which rapidly pin EB-PANI nanoparticles to the bubble/substrate interface. Micro-Raman spectra confirmed that the printed patterns preserve the molecular structure of EB-PANI. A simple transformation of the printed lines to the conducting Emeraldine salt form of PANI (ES-PANI) was achieved by doping with various acid solutions. The hypothesized deposition mechanism was verified, and the resulting structures were characterized by microscopic methods. The micro-structures displayed conductivity of 3.8×10-1 S/cm upon HCl doping and 1.5×10-1 S/cm upon H2SO4 doping, on par with state-of-the-art patterning methods. High fidelity control over the width of the printed lines down to ~650 nm was accomplished by varying the laser power and microscope stage velocity. This straightforward bottom-up method using low power lasers offers an alternative to current microfabrication techniques.
关键词： laser printing,nanoparticle assembly,polyaniline,microbubble,directed assembly
更新于2025-09-23 15:19:57
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Shaping Metallic Nanolattices: Design by Microcontact Printing from Wrinkled Stamps
摘要： A method for the fabrication of well-defined metallic nanostructures is presented here in a simple and straightforward fashion. As an alternative to lithographic techniques, this routine employs microcontact printing utilizing wrinkled stamps, which are prepared from polydimethylsiloxane (PDMS), and includes the formation of hydrophobic stripe patterns on a substrate via the transfer of oligomeric PDMS. Subsequent backfilling of the interspaces between these stripes with a hydroxyl-functional poly(2-vinyl pyridine) then provides the basic pattern for the deposition of citrate-stabilized gold nanoparticles promoted by electrostatic interaction. The resulting metallic nanostripes can be further customized by peeling off particles in a second microcontact printing step, which employs poly(ethylene imine) surface-decorated wrinkled stamps, to form nanolattices. Due to the independent adjustability of the period dimensions of the wrinkled stamps and stamp orientation with respect to the substrate, particle arrays on the (sub)micro-scale with various kinds of geometries are accessible in a straightforward fashion. This work provides an alternative, cost-effective, and scalable surface-patterning technique to fabricate nanolattice structures applicable to multiple types of functional nanoparticles. Being a top-down method, this process could be readily implemented into, e.g., the fabrication of optical and sensing devices on a large scale.
关键词： metallic nanolattices,oligomeric polydimethylsiloxane,microcontact printing,hydroxyl-functional poly(2-vinyl pyridine),gold,wrinkled stamps,nanoparticle assembly,polydimethylsiloxane wrinkles
更新于2025-09-23 15:19:57
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Three dimension nanoparticle assemblies with tunable plasmonics via a layer-by-layer process
摘要： Recently, DNA has emerged as a designer material for the controlled assembly of nanoparticles. The unique programmability of Watson-crick base pairing offers limitless control over assembly via specific interactions. At the same time, reliance on non-specific interactions, such as layer-by-layer (LbL) assembly offers a simple assembly method, albeit with limited control. Here, by assembling DNA-capped gold nanoparticles in a LbL fashion we combine these two approaches and present a simple and robust method to construct large-scale three-dimensional nanoparticle assemblies with readily tunable plasmonics. Through variation of the DNA ligand and the nanoparticle core size the morphology of the three-dimensional nanoparticle assemblies was carefully adjustabed. These morphological changes, confirmed using grazing incidence x-ray scattering, enabled the tuning of the plasmonic behavior of the three-dimensional nanoparticle assemblies. The morphology could also be modified in real-time through water vapor induced swelling enabling dynamic tuning of the optical properties. The introduction of the DNA ligand to the LbL assembly method presented here imparted tunability to the process previously inaccessible with other nanoparticle ligands and presents a platform with which to create optically active materials of various compositions.
关键词： Layer-by-layer,Plasmonics,DNA nanotechnology,Nanoparticle assembly
更新于2025-09-12 10:27:22