Indomethacin prevents TGF-ß-induced epithelial-to-mesenchymal transition in pancreatic cancer cells; evidence by Raman spectroscopy.

Pancreatic ductal adenocarcinoma (PDAC) has a very low survival rate due to the late detection and poor response to chemotherapy. Epithelial-to-mesenchymal transition (EMT) is considered an important step in tumor progression with regard to invasion and metastasis, and Transforming Growth Factor-beta (TGF-ß) signaling has been shown to play an important role in EMT. Therefore, we aimed to investigate whether indomethacin, an anti-inflammatory and analgesic drug, has any effect on TGF-ß-induced EMT in pancreatic cancer cell line and analyze the changes in their molecular structures by Raman spectroscopy and other molecular techniques. Indomethacin treated Panc-1 cells were analyzed with Raman spectroscopy, quantitative polymerase chain reaction and immunofluorescence techniques after the induction of EMT with TGF-ß. The exposure of Panc-1 cells to TGF-ß resulted in characteristic morphological alterations of EMT, and indomethacin inhibits TGF-ß-induced EMT through up-regulation of E-cadherin and down-regulation of N-cadherin and Snail expressions. Raman spectroscopy supported by principal component analysis (PCA) confirmed the effects of both TGF-ß and indomethacin. Raman spectra were further analyzed using the PCA-assisted vector machine algorithm and it was seen that the data could be classified with 97.6% accuracy. Our results suggest that indomethacin may have a significant effect on PDAC metastasis, and Raman spectroscopy was able to probe EMT-related changes and the efficacy of indomethacin in a short time and without the need for specific reagents compared to other molecular techniques.

Physically Unclonable Surfaces via Dewetting of Polymer Thin Films.

From anti-counterfeiting to biotechnology applications, there is a strong demand for encoded surfaces with multiple security layers that are prepared by stochastic processes and are adaptable to deterministic fabrication approaches. Here, we present dewetting instabilities in nanoscopic (thickness <100 nm) polymer films as a form of physically unclonable function (PUF). The inherent randomness involved in the dewetting process presents a highly suitable platform for fabricating unclonable surfaces. The thermal annealing-induced dewetting of poly(2-vinyl pyridine) (P2VP) on polystyrene-grafted substrates enables fabrication of randomly positioned functional features that are separated at a microscopic length scale, a requirement set by optical authentication systems. At a first level, PUFs can be simply and readily verified via reflection of visible light. Area-specific electrostatic interactions between P2VP and citrate-stabilized gold nanoparticles allow for fabrication of plasmonic PUFs. The strong surface-enhanced Raman scattering by plasmonic nanoparticles together with incorporation of taggants facilitates a molecular vibration-based security layer. The patterning of P2VP films presents opportunities for fabricating hybrid security labels, which can be resolved through both stochastic and deterministic pathways. The adaptability to a broad range of nanoscale materials, simplicity, versatility, compatibility with conventional fabrication approaches, and high levels of stability offer key opportunities in encoding applications.

Chemical Funneling of Colloidal Gold Nanoparticles on Printed Arrays of End-Grafted Polymers for Plasmonic Applications.

Spatially defined assembly of colloidal metallic nanoparticles is necessary for fabrication of plasmonic devices. In this study, we demonstrate high-resolution additive jet printing of end-functional polymers to serve as templates for directed self-assembly of nanoparticles into architectures with substantial plasmonic activity. The intriguing aspect of this work is the ability to form patterns of end-grafted poly(ethylene glycol) through printing on a hydrophobic layer that consists of fluoroalkylsilanes. The simultaneous dewetting of the underlying hydrophobic layer together with grafting of the printed polymer during thermal annealing enables fabrication of spatially defined binding sites for assembly of nanoparticles. The employment of electrohydrodynamic jet printing and aqueous inks together with reduction of the feature size during thermal annealing are critically important in achieving high chemical contrast patterns as small as ∼250 nm. Gold nanospheres of varying diameters selectively bind and assemble into nanostructures with reduced interparticle distances on the hydrophilic patterns of poly(ethylene glycol) surrounded with a hydrophobic background. The resulting plasmonic arrays exhibit intense and pattern-specific signals in surface-enhanced Raman scattering (SERS) spectroscopy. The localized seed-mediated growth of metallic nanostructures over the patterned gold nanospheres presents further routes for expanding the composition of the plasmonic arrays. A representative application in SERS-based surface encoding is demonstrated through large-area patterning of plasmonic structures and multiplex deposition of taggant molecules, all enabled by printing.

Synthesis of Ag and TiO2 modified polycaprolactone electrospun nanofibers (PCL/TiO2-Ag NFs) as a multifunctional material for SERS, photocatalysis and antibacterial applications.

In this study, we reported the design and the fabrication of Ag and TiO2 modified polycaprolactone (PCL) electrospun nanofiber (NF) mats. The as-prepared NF mats were fabricated by one-step electrospinning and it was exploited for three different purposes (i) reusable SERS substrate for quantitative analysis to trace organic pollutants, (ii) photocatalyst for degradation of organic pollutants and (iii) antibacterial agent for killing of bacteria. Three different nanofiber mats, PCL, PCL-TiO2, PCL/TiO2-Ag NFs. were fabricated and further investigated. The morphologies and structures of the as-prepared nanofiber mats were carried out using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FT-IR) techniques. PCL/TiO2-Ag NFs served as a highly effective SERS platform with a detection limit of 10 nM for the detection of methylene blue dye (MB). A remarkable feature of the presented platform is the ability to reuse the PCL/TiO2-Ag NFs for SERS analysis of MB; availing from its capability for self-cleaning under UV light. By employing PCL/TiO2-Ag NFs nanocatalyst, complete photocatalytic degradation of the probe analytes MB and ibuprofen (Ibu) under UV irradiation was accomplished not more than 180 min. Moreover, PCL/TiO2-Ag NF mats showed a highly promising bactericidal feature against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria, which immensely emerged due to the presence of Ag NPs. This new trending nanofiber is assumed to lead a bunch of changes in the field of photocatalytic, SERS and antibacterial studies.

Fabrication of Plasmonically Active Substrates Using Engineered Silver Nanostructures for SERS Applications.

Demanding applications in sensing, metasurfaces, catalysis, and biotechnology require fabrication of plasmonically active substrates. Herein, we demonstrate a bottom-up, versatile, and scalable approach that relies on direct growth of silver nanostructures from seed particles that were immobilized on polymer brush-grafted substrates. Our approach is based on (i) the uniform and tunable assembly of citrate-stabilized gold nanoparticles on poly(ethylene glycol) brushes to serve as seeds and (ii) the use of hydroquinone as a reducing agent, which is extremely selective to the presence of seed particles, confining the growth of silver nanostructures on the surface of the substrate. The diameter of the seed particles, concentration, as well as ratio of reactants and duration of the growth process are investigated for large-area growth of silver nanostructures with high surface coverage and plasmonic activity. The resulting silver nanostructures exhibit high levels of surface-enhanced Raman scattering activity at two different laser lines and allow detection of molecules at concentrations as low as 10 pM. The plasmonic properties of the silver nanostructures are further studied using ultrafast pump-probe spectroscopy. Spatially defined silver nanostructures are fabricated through the seed particles that are patterned via soft lithography, showing the capabilities of the presented approach in device applications.