Three-dimensional protein microarrays fabricated on reactive microsphere modified COC substrates

Fabrication of three-dimensional (3D) surface structures for the high density immobilization of biomolecules is an effective way to prepare highly sensitive biochips. In this work, a strategy to attach polymeric microspheres on a cyclic olefin copolymer (COC) substrate for the preparation of a 3D protein chip was developed. The COC surface was firstly functionalized by the photograft technique with epoxy groups, which were subsequently converted to amine groups. Then monodisperse poly(styrene-alt-maleic anhydride) (PSM) copolymer microspheres were prepared by self-stabilized precipitation polymerization and deposited as a single layer on a modified COC surface to form a 3D surface texture. The surface roughness of the COC support undergoes a significant increase from 1.4 nm to 37.1 nm after deposition of PSM microspheres with a size of 460 nm, and the modified COC still maintains a transmittance of more than 63% at the fluorescence excitation wavelengths (555 nm and 647 nm). The immobilization efficiency of immunoglobulin G (IgG) on the 3D surface reached 75.6% and the immobilization density was calculated to be 0.255 μg cm^-2, at a probe protein concentration of 200 μg mL^-1. The 3D protein microarray can be rapidly blocked by gaseous ethylenediamine within 10 minutes due to the high reactivity of anhydride groups in PSM microspheres. Immunoassay results show that the 3D protein microarray achieved specific identification of the target protein with a linear detection range from 6.25 ng mL^-1 to 250 ng mL^-1 (R² > 0.99) and a limit of detection of 8.87 ng mL^-1. This strategy offers a novel way to develop high performance polymer-based 3D protein chips.

Facile Surface Functionalization of Cyclic Olefin Copolymer Film with Anhydride Groups for Protein Microarray Fabrication

Immobilization of protein at high efficiency is a challenge for fabricating polymer-based protein chips. Here, a simple but effective approach was developed to fabricate a cyclic olefin copolymer (COC)-based protein microarray with a high immobilization density. In this strategy, poly(maleic anhydride-co-vinyl acetate) (poly(MAH-co-VAc)) brushes were facilely attached on the COC surface via UV-induced graft copolymerization. The introduction of poly(MAH-co-VAc) brushes resulted in an obvious increase in the surface roughness of COC. The functionalized COC showed little reduction in transparency compared with pristine COC, indicating that the photografting treatment did not alter its optical property. The graft density of the anhydride groups on the modified COC could be tuned from 0.46 to 3.2 μmol/cm². The immobilization efficiency of immunoglobulin G (IgG) on functionalized COC reached 88% due to the high reactivity between anhydride groups and amine groups of IgGs. An immunoassay experiment demonstrated that the microarray showed high sensitivity to the target analyte.

Highly Transparent Cyclic Olefin Copolymer Film with a Nanotextured Surface Prepared by One-Step Photografting for High-Density DNA Immobilization

Compared with conventional glass slides and two-dimensional (2D) planar microarrays, polymer-based support materials and three-dimensional (3D) surface structures have attracted increasing attention in the field of biochips because of their good processability in microfabrication and low cost in mass production, as well as their improved sensitivity and specificity for the detection of biomolecules. In the present study, UV-induced emulsion graft polymerization was carried out on a cyclic olefin copolymer (COC) surface to generate 3D nanotextures composed of loosely stacked nanoparticles with a diameter of approximately 50 nm. The introduction of a hierarchical nanostructure on a COC surface only resulted in a 5% decrease in its transparency at a wavelength of 550 nm but significantly increased the surface area, which markedly improved immobilization density and efficiency of an oligonucleotide probe compared with the functional group and polymer brush-modified substrates. The highest immobilization efficiency of the probes reached 93%, and a limit of detection of 75 pM could be obtained. The hybridization experiment demonstrated that the 3D gene chip exhibited excellent sensitivity for target DNA detection and single-nucleotide polymorphism discrimination. This one-step approach to the construction of nanotextured surfaces on the COC has promising applications in the fields of biochips and immunoassays.

Mild and Selective C-H Activation of COC Microfluidic Channels Allowing Covalent Multifunctional Coatings

Plastics, such as cyclic olefin copolymer (COC), are becoming an increasingly popular material for microfluidics. COC is used, in part, because of its (bio)-chemical resistance. However, its inertness and hydrophobicity can be a major downside for many bioapplications. In this paper, we show the first example of a surface-bound selective C-H activation of COC into alcohol C-OH moieties under mild aqueous conditions at room temperature. The nucleophilic COC-OH surface allows for subsequent covalent attachments, such as of a H-terminated silane. The resulting hybrid material (COC-Si-H) was then modified via a photolithographic hydrosilylation in the presence of ω-functionalized 1-alkenes to form a new highly stable, solvent-resistant hybrid surface.

Atmospheric Solid Analysis Probe-Ion Mobility Mass Spectrometry: An Original Approach to Characterize Grafting on Cyclic Olefin Copolymer Surfaces

A cyclic olefin copolymer (COC) was grafted with aryl layers from aryldiazonium salts, and then we combined infrared spectrometry, atomic force microscopy (AFM), and ion mobility mass spectrometry with atmospheric solid analysis probe ionization (ASAP-IM-MS) to characterize the aryl layers. ASAP is a recent atmospheric ionization method dedicated to the direct analysis of solid samples. We demonstrated that ASAP-IM-MS is complementary to other techniques for characterizing bromine and sulfur derivatives of COC on surfaces. ASAP-IM-MS was useful for optimizing experimental grafting conditions and to elucidate hypotheses around aryl layer formation during the grafting process. Thus, ASAP-IM-MS is a good candidate tool to characterize covalent grafting on COC surfaces.

Anaerobic ammonium oxidation (ANAMMOX) sludge immobilized by waterborne polyurethane and its nitrogen removal performance-a lab scale study

ANAMMOX granules immobilized by WPU exhibited the best entrapment support, superb bioactivity, high nitrogen removal rate and highest mechanical stability.