Controllable assembly of high sticky and flexibility surface-enhanced Raman scattering substrate for on-site target pesticide residues detection.

Pesticide residues in fruit and vegetable constitute a great threat to mankind's health, and a technique of rapid, cost-effective, ultra-sensitive and non-destructive analysis is especially critical for on-site detection in practical application. A strategy was utilized to fabricate highly viscous and flexible WPU@AgNPs sticky tape for the rapid extraction and Surface-enhanced Raman Scattering (SERS) assay of thiabendazole residues on the surface of fruits. Simply put, the novel WPU@AgNPs tapes were constructed by decorating the waterborne polyurethane (WPU) film with silver nanoparticles (AgNPs), and demonstrated excellent sensitivity with 4-Mercaptopyridine (4-Mpy) as the probe molecule. Meanwhile, the enhancement factor of the novel SERS substrate could reach 7.01 × 106, which was consistent with the finite difference time domain (FDTD) theoretical simulation results. What's more, the high viscosity and flexibility of WPU@AgNPs sticky tapes allowed them to detect the thiabendazole residues on the pear, apple and banana surfaces by a straightforward "paste and peel off" approach. The results showed that the detection limit could reach 1.44, 1.12 and 1.63 ng/cm2. This strategy would be as a common method for prompt, on-site and ultra-sensitive assay of thiabendazole residues in chemical and biological fields.

Flexible Hydrophobic CFP@PDA@AuNPs Stripes for Highly Sensitive SERS Detection of Methylene Blue Residue.

Considering the inherent hydrophilic and porous nature of paper, the rapid absorption and diffusion of aqueous analyte solutions on paper-based SERS substrates may severely affect the Raman detection sensitivity and accuracy in the detection of target molecules. In this work, a series of hydrophobic CFP@PDA@AuNPs stripes were obtained through in situ synthesizing of gold nanoparticles (AuNPs) on a polydopamine (PDA)-decorated cellulose filter paper (CFP) and functionalized with perfluorodecanethiol (PFDT). When the SERS performance of the substrates was examined using 4-ATP, the hydrophobic CFP@PDA@AuNPs substrate showed superior sensitivity, reproducibility and stability due to the hydrophobic enrichment effect, with the detection limit decreasing to 10-9 M and the enhancement factor as high as 2.55 × 107. More importantly, it was feasible to apply the hydrophobic paper substrate as an excellent SERS sensor to detect methylene blue (MB) residues in lake water in a highly sensitive manner. The lowest detectable limit of MB was 100 nM, and it showed a low relatively standard deviation (RSD) value of 5.28%. Hydrophobic CFP@PDA@AuNPs stripes may serve as excellent sensors for target molecule detection and have tremendous potential in food security, and environmental and chemical detection.

Construction of flexible, transparent and mechanically robust SERS-active substrate with an efficient spin coating method for rapidin-situtarget molecules detection.

Flexible, transparent and mechanically robust surface enhanced Raman scattering (SERS)-active substrates is currently the most attractive research focus in the field of Raman detection, and also a powerful analysis and identification technique in the biological research. Herein, we introduced a low-cost and large-scale method to fabricate flexible and transparent AgNPs/WPU plasmonic metafilm with monolayer-island phase nanostructures based on silver nanoparticles (AgNPs) and waterborne polyurethane emulsion (WPU) film. The obtained AgNPs/WPU plasmonic metafilm demonstrated excellent SERS sensitivity, signal uniformity and reproducibility, and the SERS substrates could still maintain excellent stability even after being bent or stretched over 100 cycles. The detection concentration was as low as 10-9M with 4-Mercaptobenzoic acid (4-MBA) as probe molecule, and the enhancement factor was high to 2.2 × 107. More importantly, the flexibility and adhesivity of AgNPs/WPU plasmonic metafilm could be directly conformal coverage on the apple surface forin situdetection of thiram residue, and the detection limit was as low as 9.0165 ng cm-2. This versatile AgNPs/WPU plasmonic metalfilm would be a promising SERS substrate for the detection of pesticide residue in chemical and biological applications.

Ultrafast Ion Sieving from Honeycomb-like Polyamide Membranes Formed Using Porous Protein Assemblies.

Despite the commercial success of thin film composite polyamide membranes, further improvements to the water permeation of polyamide membranes without degradation in product water quality remain a great challenge. Herein, we report the fabrication of an interfacially polymerized polyamide nanofiltration membrane with a novel 3D honeycomb-like spatial structure, which is formed from a tobacco mosaic virus (TMV) porous protein nanosheet-coated microfiltration membrane support. TMV nanosheets with uniform pores and appropriate hydrophilicity deposited inside the support membrane pores facilitate the construction of a localized water-oil reaction interface with evenly distributed monomers and guide the formation of a defect-free polyamide layer with a spatial structure that copies the geometry of the membrane cavities. Such a 3D morphology possesses ultrahigh specific surface area, leading to unprecedented membrane water permeance as high as 84 L m-2 h-1 bar-1, high MgSO4 rejection of 98%, and monovalent/divalent ion sieving selectivity up to 89.

Precise Fabrication of De Novo Nanoparticle Lattices on Dynamic 2D Protein Crystalline Lattices.

The science of protein self-assembly has experienced significant development, from discrete building blocks of self-assembled nanoarchitectures to advanced nanostructures with adaptive functionalities. Despite the prominent achievements in the field, the desire of designing de novo protein-nanoparticle (NP) complexes and constructing dynamic NP systems remains highly challenging. In previous works, l-rhamnulose-1-phosphate aldolase (C98RhuA) tetramers were self-assembled into two-dimensional (2D) lattices via disulfide bond interactions. These interactions provided 2D lattices with high structural quality and a sophisticated assembly mode. In this study, we devised a rational design for RhuA building blocks to fabricate 2D functionalized protein lattices. More importantly, the lattices were used to direct the precise assembly of NPs into highly ordered and diverse nanoarchitectures. These structures can be employed as an excellent tool to adequately verify the self-assembly mode and structural quality of the designed RhuA crystals. The subsequent redesign of RhuA building blocks enabled us to predictably produce a novel protein lattice whose conformational dynamics can be controllably regulated. Thus, a dynamic system of AuNP lattices was achieved. Transmission electron microscopy and small-angle X-ray scattering indicated the presence of these diverse NP lattices. This contribution enables the fabrication of future NP structures in a more programmable manner with more expected properties for potential applications in nanoelectronics and other fields.

Dual Functional Modification of Alkaline Amino Acids Induces the Self-Assembly of Cylinder-Like Tobacco Mosaic Virus Coat Proteins into Gear-Like Architectures.

Herein, the assembly of 3D uniform gear-like architectures is demonstrated with a tobacco mosaic virus (TMV) disk as a building block. In this context, the intrinsic behavior of the TMV disk that promotes its assembly into nanotubes is altered by a synergistic effect of dual functional modifications at the 53rd arginine mutation and the introduction of lysine groups in the periphery at 1st and 158th positions of the TMV disk, which results in the formation of 3D gear-like superstructures. Therein, the 53rd arginine moiety significantly strengthens the linkage between TMV disks in the alkaline environment through hydrogen bond interactions. The charge of lysine-modified lateral surfaces is partially neutralized in the alkaline solution, which induces the TMV disk to form a gear-like architecture to maintain its structural stability by exploiting the electrostatic repulsion between neighboring TMV disks. This study not only provides explicit evidence regarding the molecular-level understanding of how the modification of site-specific amino acid affects the assembly of resultant superstructures but also encourages the fabrication of functional protein-based nanoarchitectures.

Toward Precise Manipulation of DNA-Protein Hybrid Nanoarchitectures.

Nucleic acids and proteins are the two primary building materials of living organisms. Over the past decade, artificial DNA-protein hybrid structures have been pursued for a wide range of applications. DNA nanotechnology, in particular, has dramatically expanded nanoscale molecule engineering and contributed to the spatial arrangement of protein components. Strategies for designing site-specific coupling of DNA oligomers to proteins are needed in order to allow for precise control over stoichiometry and position. Efforts have also been focused on coassembly of protein-DNA complexes by engineering their fundamental molecular recognition interactions. This Concept focuses on the precise manipulation of DNA-protein nanoarchitectures. Particular attention is paid to site-selectivity within DNA-protein conjugates, regulation of protein orientation using DNA scaffolds, and coassembly principles upon unique structural motifs. Current challenges and future directions are also discussed in the design and application of DNA-protein nanoarchitectures.

Overcoming resistance to cisplatin by inhibition of glutathione S-transferases (GSTs) with ethacraplatin micelles in vitro and in vivo.

Platinum-based DNA-adducting agents are used extensively in the clinic for cancer chemotherapy. However, the anti-tumor efficacy of these drugs is severely limited by cisplatin resistance, and this can lead to the failure of chemotherapy. One of cisplatin resistance mechanisms is associated with overexpression of glutathione S-transferases (GSTs), which would accelerate the deactivation of cisplatin and decrease its antitumor efficiency. Nanoscale micelles encapsulating ethacraplatin, a conjugate of cisplatin and ethacrynic acid (an effective GSTs inhibitor), can enhance the accumulation of active cisplatin in cancer cells by inhibiting the activity of GSTs and circumventing deactivation of cisplatin. In vitro and in vivo results provide strong evidence that GSTs inhibitor-modified cisplatin prodrug combined with nanoparticle encapsulation favor high effective platinum accumulation, significantly enhanced antitumor efficacy against cisplatin-resistant cancer and decreased system toxicity. It is believed that these ethacraplatin-loaded micelles have the ability of overcoming resistance of cancers toward cisplatin and will improve the prospects for chemotherapy of cisplatin-resistant cancers in the near future.