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Spherical structures built from uni- and multilamellar lipid bilayers (LUV and MLV) are nowadays considered not just as nanocarriers of various kinds of therapeutics, but also as the vehicles that, when coupled with gold (Au) nanoparticles (NPs), can also serve as a tool for imaging and discriminating healthy and diseased tissues. Since the presence of Au NPs or their aggregates may affect the properties of the drug delivery vehicle, we investigated how the shape and position of Au NP aggregates adsorbed on the surface of MLV affect the arrangement and conformation of lipid molecules. By preparing MLVs constituted from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of uncoated Au NP aggregates found i) both within liposome core and on the surface of the outer lipid bilayer, or ii) adsorbed on the outer lipid bilayer surface only, we demonstrated the maintenance of lipid bilayer integrity by microscopic techniques (cryo-TEM, and AFM). The employment of SERS and FTIR-ATR techniques enabled us not only to elucidate the lipid interaction pattern and their orientation in regards to Au NP aggregates but also unequivocally confirmed the impact of Au NP aggregates on the persistence/breaking of van der Waals interactions between hydrocarbon chains of DPPC. [ABSTRACT FROM AUTHOR]

Aptamers are functional small single-strand oligonucleotides (DNA) that show high affinity to their target molecules such as proteins or small analytes through the formation of specific secondary structures. In the present paper, we study the interaction of one aptamer with its target protein, the manganese superoxide dismutase (MnSOD), under specific conditions of surface chemical grafting. For this purpose, we exploit two different chemical strategies to graft the aptamers onto pegylated gold nanoparticles: the carbodiimide chemistry (EDC/NHS method) and the thiol covalent bond (S–Au bond). We also study the influence of the presence of a spacer of 15 thymine bases at the aptamer extremity. The aptamer interactions with the MnSOD were characterized by UV-Vis absorption on a large range of MnSOD concentrations (from 10−12 up to 10−5 M). We observe that the interaction is strongly dependent on the MnSOD concentration and also on the aptamer structure at the surface of the gold nanoparticles. We demonstrate that the highest affinity is obtained for the aptamer with the 15 thymine bases spacer and grafted with the carbodiimide method. We assume that the grafting method has a strong influence on the accessibility and the conformation of the aptamer at the nanoparticle surface and thus on its possibility to interact with the MnSOD. [ABSTRACT FROM AUTHOR]

Abstract: Improvement of product quality is required more than ever for mass production of micro formed parts. The process of micro multi-point forming with cushion has been simulated in this paper by finite element model which incorporates a constitutive relation with consideration of size effect. The effect of the cushion material, cushion thickness and coefficient of friction on the surface quality of the deformed sheet has been investigated. It has been found that a proper selection of the cushion material and optimum cushion thickness can significantly improve the surface quality. In addition, this paper also discusses the influence of the cushion material and coefficient of friction on the sheet thickness distribution. Better surface quality and thickness distribution can be obtained with good lubricating condition. [Copyright &y& Elsevier]

• New hybrid bio nanosystem: Ability to bind glucose. • Stabilization and biomolecular interaction monitoring applications. • New colorimetric assay for the simple detection of glucose for specific applications, e.g. cancer treatment. • New analytical platform for understanding the molecular basis of physiological and pathological events. Galectins (Gal) are a family of dimeric lectins, composed by two galactoside-binding sites implicated in the regulation of cancer progression and immune responses. In this study, we report for the first time the synthesis and the physical-chemical characterization of galectin-1-complex-gold COOH-terminated polyethlenglicole (PEG)-coated NPs (Gal-1 IN PEG-AuNPs) and their ability to recognize glucose in an aqueous solution with a concentration varying from 10 mM to 100 pM. The chemical protocol consistsof three steps: (i) complexation between galectin-1Gal-1 and tetrachloroauric acid (HAuCl 4) to form gold-protein grains; (ii) staking process of COOH-terminated polyethlenglicole molecules (PEG) onto Gal-1-Au complex and (iii) reduction of hybrid metal ions to obtain a colloidal stable solution. During the complexation, the spectral signatures related to the Gal-1 orientation on the gold surface have been found to change due to its protonation state. The effective glucose monitoring was detected by UV–vis, Raman spectroscopy and Transmission Electron Microscopy (TEM). Overall, we observed that the interaction is strongly dependent on the Gal-1 conformation at the surface of gold nanoparticles. [ABSTRACT FROM AUTHOR]

A label-free surface-enhanced Raman scattering (SERS) was designed for sensitive detection of interleukin-6 (IL-6). The sensing element composed of anti-IL-6 antibodies adsorbed on the surface of spherical gold nanoparticles (AuNPs) as SERS-active surface. The principle of detection was probing antibody conformational changes using its intrinsic SERS fingerprint after binding to IL-6. Comparison of SERS spectra of antibody before and after binding to IL-6 showed that secondary structure of antibody does not change upon binding to IL-6. Vibrational information from disulfide bonds ν (S S) in antibody structure indicated some changes of geometry around S S bridges as a consequence of the immunocomplex formation. Transmission electron microscopy (TEM) and UV–Vis spectroscopy were used to confirm AuNPs conjugation with antibody as well as IL-6 binding to antibody on the surface of AuNPs. The SERS-based immunoassay showed a wide linear range (2.0–1000 pg mL−1) and a high sensitivity with a limit of detection (LOD) as low as 0.91 pg mL−1 (0.04 pM) without using any extrinsic Raman label. UV–Vis spectroscopy was employed as a conventional method for IL-6 detection based on observation of any change in the position of localized surface plasmon resonance (LSPR) band of AuNPs-antibody conjugates with LOD of 10 ng mL−1. [Display omitted] • A label-free SERS immunoassay biosensor was developed for detection of Interleukin 6. • Antibody against Interleukin 6 was immobilized on the surface of gold nanoparticles. • Interleukin 6 binding to antibody induced conformational changes of antibody. • IL-6 was realized using the vibrational information from disulfide bonds ν (S S) in antibody structure. • The designed platform showed pico-scale LOD. [ABSTRACT FROM AUTHOR]

Based on high sensitivity, specific fingerprinting spectra and real-time detection, surface-enhanced Raman spectroscopy (SERS) is a powerful tool for the observation, the detection and the identification of chemical or biological species at low concentrations. One of the key elements for the SERS detection is the choice of SERS substrate. This latter one can be either a home-made one or either commercially purchased. For researchers who don't have facilities to fabricate SERS substrates, the commercial ones are a necessary and optimal choice. Thus, a comprehensive evaluation of their reproducibility is urgently needed and carried out in this paper. The blank spectra as well as the SERS spectra of three probes molecules (4-mercaptobenzoic acid (4-MBA), 1, 2-bis (4-pyridyl) ethylene (BPE) and methylene blue (MB)) were analysed for two excitation wavelengths (532 and 785 nm). The most suitable detection condition was determined for each substrate. Under the optimum conditions, the SERS mapping were carried to measure the relative standard deviations (RSDs) to further evaluate the reproducibility of the substrates. The results demonstrated that the Enspectrc, Q-SERSTM and Hamamatsu substrates were the more suitable for reproducible SERS measurements. [ABSTRACT FROM AUTHOR]