Hierarchical-Multiplex DNA Patterns Mediated by Polymer Brush Nanocone Arrays That Possess Potential Application for Specific DNA Sensing

Advances in design of polymer brush functionalized inorganic nanomaterials and their applications in biomedical arena

Grafting of polymer brush (assembly of polymer chains tethered to the substrate by one end) is emerging as one of the most viable approach to alter the surface of inorganic nanomaterials. Inorganic nanomaterials despite their intrinsic functional superiority, their applications remain restricted due to their incompatibility with organic or biological moieties vis-à-vis agglomeration issues. To overcome such a shortcoming, polymer brush modified surfaces of inorganic nanomaterials have lately proved to be of immense potential. For example, polymer brush-modified inorganic nanomaterials can act as efficient substrates/platforms in biomedical applications, ranging from drug-delivery to protein-array due to their integrated advantages such as amphiphilicity, stimuli responsiveness, enhanced biocompatibility, and so on. In this review, the current state of the art related to polymer brush-modified inorganic nanomaterials focusing, not only, on their synthetic strategies and applications in biomedical field but also the architectural influence of polymer brushes on the responsiveness properties of modified nanomaterials have comprehensively been discussed and its associated future perspective is also presented. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Strategy based on multiplexed brush architectures for regulating the spatiotemporal immobilization of biomolecules

Functional surfaces that enable both spatial and temporal control of biomolecules immobilization have attracted enormous attention for various fields including smart biointerface materials, high-throughput bioarrays, and fundamental research in the biosciences. Here, a flexible and promising method was presented for regulating the spatiotemporal arrangement of multiple biomolecules by constructing the topographically and chemically diverse polymer brushes patterned surfaces. A series of polymer brushes patterned surfaces, including antifouling brushes patterned surface, epoxy-presenting brushes patterned surface without and with antifouling background layer, were fabricated to control the spatial distribution of protein and cell adhesion through specific and nonspecific means. The fluorescence measurements demonstrated the effectiveness of spatially regulating the density of surface-immobilized protein through controlling the areal thickness of the poly (glycidyl methacrylate) (PGMA) brush patterns, leading to various complex patterns featuring well-defined biomolecule concentration gradients. Furthermore, a multiplexed surface bearing epoxy groups and azido groups with various areal densities was fabricated for regulating the spatiotemporal arrangement of different proteins, enabling binary biomolecules patterns with higher degrees of functionality and complexity. The presented strategy for the spatiotemporal control of biomolecules immobilization would boost the development of dynamic and multifunctional biosystems.

Evolution and applications of polymer brush hypersurface photolithography

Hypersurface photolithography creates arbitrary polymer brush patterns with independent control over feature diameter, height, and spacing between features, while controlling composition along a polymer chain and between features.

Underwater Superoleophobic Surface Based on Silica Hierarchical Cylinder Arrays with a Low Aspect Ratio

A superantiwetting surface based on low-aspect-ratio hierarchical cylinder arrays (HCAs) was successfully obtained on a silica substrate by colloidal lithography with photolithography. Colloidal lithography is a technique involving transfer of a pattern to a substrate by etching or exposure to a radiation source through a mask composed of a packed colloidal crystal, while photolithography is utilized by which a pattern is transferred photographically to a photoresist-coated substrate, and the substrate is subsequently etched. The surface provides an alternative approach to apply aligned micro-nano integrated structures with a relatively low aspect ratio in superantiwetting. The obtained HCAs successfully integrated micro- and nanoscale structures into one system, and the physical structure of the HCAs can be tuned by modulating the fabrication approach. Using a postmodification process, the underwater-oil wetting behavior of cylinder-array based surfaces can be easily modulated from the superoleophobic state (an oil contact angle (OCA) of 161°) to oleophilic state (an OCA of 19°). Moreover, the underwater-oil wettability can be reversibly transformed from the superoleophobic state (an OCA of approximately 153°) into the oleophilic state (an OCA of approximately 31°) by grafting stimuli-responsive polymer (PNIPAAm) brushes onto this specific hierarchical structure. Due to the temperature-responsive property, modifying the surface with PNIPAAm provides a possibility to control the oil wettability (repellent or sticky) by temperature, which will benefit the use of HCAs in oil-water separation and other application fields.

Development of Sphere-Polymer Brush Hierarchical Nanostructure Substrates for Fabricating Microarrays with High Performance

In this work, a sphere-polymer brush hierarchical nanostructure-modified glass slide has been developed for fabricating high-performance microarrays. The substrate consists of a uniform 160 nm silica particle-self-assembled monolayer on a glass slide with a postcoated poly(glycidyl methacrylate) (PGMA) brush layer (termed PGMA@3D(160) substrate), which can provide three-dimensional (3D) polymer brushes containing abundant epoxy groups for directly immobilizing various biomolecules. As a typical example, the interactions of three monosaccharides (4-aminophenyl β-d-galactopyranoside, 4-aminophenyl β-d-glucopyranoside, and 4-aminophenyl α-d-mannopyranoside) with two lectins (biotinylated ricinus communis agglutinin 120 and biotinylated concanavalin A from Canavalia ensiformis) have been assessed by PGMA@3D(160) substrate-based carbohydrate microarrays. The carbohydrate microarrays show good selectivity, strong multivalent interaction, and low limit of detection (LOD) in the picomolar range without any signal amplification. Furthermore, the proposed sphere-polymer brush hierarchical nanostructure substrates can be easily extended to fabricate other types of microarrays for DNA and protein detection. PGMA@3D(160) substrate-based microarrays exhibit higher reaction efficiencies and lower LODs (by at least 1 order of magnitude) in comparison to those of two-dimensional microarrays, which are fabricated on planar epoxy substrates, making it a promising platform for bioanalytical and biomedical applications.

A Programmable DNA Double-Write Material: Synergy of Photolithography and Self-Assembly Nanofabrication

We demonstrate a DNA double-write process that uses UV to pattern a uniquely designed DNA write material, which produces two distinct binding identities for hybridizing two different complementary DNA sequences. The process requires no modification to the DNA by chemical reagents and allows programmed DNA self-assembly and further UV patterning in the UV exposed and nonexposed areas. Multilayered DNA patterning with hybridization of fluorescently labeled complementary DNA sequences, biotin probe/fluorescent streptavidin complexes, and DNA patterns with 500 nm line widths were all demonstrated.

Poly(glycidyl methacrylate-co-2-hydroxyethyl methacrylate) Brushes as Peptide/Protein Microarray Substrate for Improving Protein Binding and Functionality

We developed a three-dimensional (3D) polymer-brush substrate for protein and peptide microarray fabrication, and this substrate was facilely prepared by copolymerization of glycidyl methacrylate (GMA) and 2-hydroxyethyl methacrylate (HEMA) monomers via surface-initiated atom transfer radical polymerization (SI-ATRP) on a glass slide. The performance of obtained poly(glycidyl methacrylate-co-2-hydroxyethyl methacrylate) (P(GMA-HEMA)) brush substrate was assessed by binding of human IgG with rabbit antihuman IgG antibodies on a protein microarray and by the determination of matrix metalloproteinase (MMP) activities on a peptide microarray. The P(GMA-HEMA) brush substrate exhibited higher immobilization capacities for proteins and peptides than those of a two-dimensional (2D) planar epoxy slide. Furthermore, the sensitivity of the P(GMA-HEMA) brush-based microarray on rabbit antihuman IgG antibody detection was much higher than that of its 2D counterpart. The enzyme activities of MMPs were determined specifically with a low detection limit of 6.0 pg mL(-1) for MMP-2 and 5.7 pg mL(-1) for MMP-9. By taking advantage of the biocompatibility of PHEMA, the P(GMA-HEMA) brush-based peptide microarray was also employed to evaluate the secretion of MMP-2 and MMP-9 by cells cultured off the chip or directly on the chip, and satisfactory results were obtained.