Multi-layered plasma-polymerized chips for SPR-based detection

Design and screening of a novel neuropilin-1 targeted penetrating peptide for anti-angiogenic therapy in glioma

AIMS

This study aimed to design and screen a dual functional fusion peptide that could penetrate the blood-brain barrier and target neuropilin 1 (NRP1) overexpressed in vascular endothelial cells for the anti-angiogenesis of glioma treatment.

MAIN METHODS

At the cellular level, the in vitro anti-angiogenic activity of six NRP1 targeting peptides was screened by testing the ability to inhibit the proliferation and tube formation of HUVECs. Then, the in vitro anti-angiogenic activity of two fusion peptides containing different linkers was screened by testing the ability to inhibit HUVECs proliferation, tube formation and migration. The effect of fusion peptide on VEGFR2 related signal pathway was confirmed by Western-blotting. Surface plasmon resonance technology was used to detect the affinity of the fusion peptide to NRP1. The ability of FITC-labeled peptides to penetrate cells was confirmed by cell uptake assay. By establishing an orthotopic glioma model, we evaluated the ability of FITC-labeled peptides to penetrate the blood-brain barrier and their anti-glioma growth activity in vivo.

KEY FINDINGS

We found that NRP1 targeting peptide RP7 and linker cysteine were the most suitable key components in the fusion peptide. We also found that the fusion peptide Tat-C-RP7 we constructed had the strongest ability to penetrate the blood-brain barrier and anti-angiogenic activity in vitro and in vivo.

SIGNIFICANCE

At present, NRP1 targeting peptide as a drug delivery tool and molecular probe seems to have received more attention. We constructed a fusion peptide Tat-C-RP7 with strong anti-angiogenic activity for the treatment of glioma.

In situ generated nanozyme-initiated cascade reaction for amplified surface plasmon resonance sensing

A novel nanozyme-amplified surface plasmon resonance (SPR) sensor was successfully developed based on target-induced in situ generation of AuNPs and a AuNP-guided cascade amplification reaction, with Hg²⁺ as the target analyte.

Novel epoxy-silica nanoparticles to develop non-enzymatic colorimetric probe for analytical immuno/bioassays

We have developed a novel method to develop epoxy silica nanoparticles (EfSiNP) in a single pot. High surface coverage of epoxy functional groups between 150 and 57000 molecules per particles (∼10¹³-10¹⁶ molecules/mL of 200 nm EfSiNPs) was achieved for different preparation conditions. We then created a red colored probe by conjugating Fuchsin dye to the epoxy functionalities of EfSINPs. Anti-mouse IgG was co-immobilized with Fuchsin and their ratios were optimized for achieving optimum ratios by testing those in functional assays. Dye to antibody ratios were in good negative correlation with a coefficient of -1.00 measured at a confidence level of over 99%. We employed the developed non-enzymatic colorimetric immunonanoprobe for detecting mouse IgG in a direct immunoassay format. We achieved a sensitivity of 427 pg/mL with the assay.

Dynamic Dispersal of Surface Layer Biofilm Induced by Nanosized TiO2 Based on Surface Plasmon Resonance and Waveguide

Pollutant degradation is present mainly in the surface layer of biofilms, and the surface layer is the most vulnerable to impairment by toxic pollutants. In this work, the effects of nanosized TiO₂ (n-TiO₂) on the average thicknesses of Bacillus subtilis biofilm and on bacterial attachment on different surfaces were investigated. The binding mechanism of n-TiO₂ to the cell surface was also probed. The results revealed that n-TiO₂ caused biofilm dispersal and the thicknesses decreased by 2.0 to 2.6 μm after several hours of exposure. The attachment abilities of bacteria with extracellular polymeric substances (EPS) on hydrophilic surfaces were significantly reduced by 31% and 81% under 10 and 100 mg/liter of n-TiO₂, respectively, whereas those of bacteria without EPS were significantly reduced by 43% and 87%, respectively. The attachment abilities of bacteria with and without EPS on hydrophobic surfaces were significantly reduced by 50% and 56%, respectively, under 100 mg/liter of n-TiO₂ The results demonstrated that biofilm dispersal can be attributed to the changes in the cell surface structure and the reduction of microbial attachment ability.IMPORTANCE Nanoparticles can penetrate into the outer layer of biofilm in a relatively short period and can bind onto EPS and bacterial surfaces. The current work probed the effects of nanosized TiO₂ (n-TiO₂) on biofilm thickness, bacterial migration, and surface properties of the cell in the early stage using the surface plasmon resonance waveguide mode. The results demonstrated that n-TiO₂ decreased the adhesive ability of both cell and EPS and induced bacterial migration and biofilm detachment in several hours. The decreased adhesive ability of microbes and EPS worked against microbial aggregation, reducing the effluent quality in the biological wastewater treatment process.

Controlling wettability of PECVD-deposited dual organosilicon/carboxylic acid films to influence DNA hybridisation assay efficiency

Plasma oxidation of Zeonor and deposition of TEOS/AA thin film showing dual layer effect on the surface.

Facile Functionalization of Polymer Surfaces in Aqueous and Polar Organic Solvents via 3-Mercaptopropylsilatrane

Surface modification of a polymer substrate with a mercapto functionality is crucial in many applications such as flexible circuitry and point-of-care biosensors. We present here a novel bifunctional molecular adhesive, 3-mercaptopropylsilatrane (MPS), as an interface between polymer and metal surfaces. Under ambient conditions, surface modification of polymer surfaces with a mercapto functionality can be achieved with low concentration (0.46 mM) of MPS in aqueous solvent (50% ethanol) in a short time (<30 min). Three popular polymers for optical sensors, polycarbonate, polyethylene terephthalate, and poly(methyl methacrylate), were employed as substrates, and MPS films formed on these substrates were examined and compared with that on a glass substrate. The films were characterized by UV-vis spectroscopy, water contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy. MPS was also used as a bifunctional linker for the construction of a gold nanoparticle (AuNP) sub-monolayer on these polymer surfaces. Under optimized preparation conditions, the absorbance and full width at half-maximum of the plasmon band are comparable to those of a AuNP-modified glass substrate. Hence, MPS may have a potential to be a key component in polymer substrate-based localized surface plasmon resonance sensors. A self-catalytic surface reaction mechanism is also proposed to account for the results. As compared to a glass surface with a high number of silanol groups, the successful formation of an MPS film on polymer surfaces with relatively few reactive sites is probably due to the lateral polymerization of MPS starting from a condensed MPS molecule on a reactive site of a polymer surface.

Plasma-Fabricated Surface Plasmon Resonance Chip for Biosensing

This work reports the fabrication of a biosensing chip surface designed for plasmonic detection, and features a layer of noble metal nanoparticles encapsulated as a sandwich within amine-functionalized polysiloxane layers formed by plasma-enhanced chemical vapour deposition. The collective surface plasmon resonance (CSPR) phenomenon characteristic of a dense particle layer is demonstrated for encapsulated gold nanoparticles of different diameters. Biomolecular immobilization is carried out through the amine functional groups that are part of the encapsulating layer. The detection of biomolecular binding events at the sensor surface is demonstrated both by a shift in resonance wavelength at constant angle of incidence using SPR-enhanced spectroscopic ellipsometry and by detecting the angular shift in resonance in a commercial SPR instrument (Biacore®). Taken with other results, this work shows how a complete SPR chip can be assembled by a rapid sequence of operations in a single plasma chamber.

Scalable low-cost fabrication of disposable paper sensors for DNA detection

Controlled integration of features that enhance the analytical performance of a sensor chip is a challenging task in the development of paper sensors. A critical issue in the fabrication of low-cost biosensor chips is the activation of the device surface in a reliable and controllable manner compatible with large-scale production. Here, we report stable, well-adherent, and repeatable site-selective deposition of bioreactive amine functionalities and biorepellant polyethylene glycol-like (PEG) functionalities on paper sensors by aerosol-assisted, atmospheric-pressure, plasma-enhanced chemical vapor deposition. This approach requires only 20 s of deposition time, compared to previous reports on cellulose functionalization, which takes hours. A detailed analysis of the near-edge X-ray absorption fine structure (NEXAFS) and its sensitivity to the local electronic structure of the carbon and nitrogen functionalities. σ*, π*, and Rydberg transitions in C and N K-edges are presented. Application of the plasma-processed paper sensors in DNA detection is also demonstrated.