Spatially selective surface platforms for binding fibrinogen prepared by particle lithography with organosilanes

Abstract

One contribution of 10 to a Theme Issue 'Molecular-, nano-and micro-devices for real-time in vivo sensing'. We introduce an approach based on particle lithography to prepare spatially selective surface platforms of organosilanes that are suitable for nanoscale studies of protein binding. Particle lithography was applied for patterning fibrinogen, a plasma protein that has a major role in the clotting cascade for blood coagulation and wound healing. Surface nanopatterns of mercaptosilanes were designed as sites for the attachment of fibrinogen within a protein-resistant matrix of 2-[methoxy( polyethyleneoxy)propyl] trichlorosilane (PEG-silane). Preparing site-selective surfaces was problematic in our studies, because of the self-reactive properties of PEG-organosilanes. Certain organosilanes presenting hydroxyl head groups will cross react to form mixed surface multi-layers. We developed a clever strategy with particle lithography using masks of silica mesospheres to protect small, discrete regions of the surface from cross reactions. Images acquired with atomic force microscopy (AFM) disclose that fibrinogen attached primarily to the surface areas presenting thiol head groups, which were surrounded by PEG-silane. The activity for binding anti-fibrinogen was further evaluated using ex situ AFM studies, confirming that after immobilization the fibrinogen nanopatterns retained capacity for binding immunoglobulin G. Studies with AFM provide advantages of achieving nanoscale resolution for detecting surface changes during steps of biochemical surface reactions, without requiring chemical modification of proteins or fluorescent labels.

Nanometric Protein-Patch Arrays on Glass and Polydimethylsiloxane for Cell Adhesion Studies

“…A different promising approach for nanopatterning is the use of self-assembled masks, for example, those made of colloidal beads, − for vapor deposition of organo-aminosilane molecules that are subsequently functionalized with the desired protein. The evaporation mask can be made via phase separation of polymers, from ordered anodic alumina membranes, or via colloidal-bead lithography − (see ref for a review).…”

Picoliter Well Array Chip-Based Digital Recombinase Polymerase Amplification for Absolute Quantification of Nucleic Acids

“…To covalently couple methoxy-PEG-silane (2-[methoxy(polyethyleneoxy)propyl]-trimethoxysilane; J&K Scientific, Beijing, China) to the PWA chip surface, the bare chips were treated in an oxygen plasma for 30 s to clean the surfaces (Mercator Control Systems, Inc., Santa Ana, CA, USA). Then, they were placed in 1 g of methoxy-PEG-silane dissolved in 100 mL of anhydrous toluene with 1% triethylamine as a catalyst overnight at room temperature [68,69]. Before the application of the PWA chip, the physically adsorbed methoxy-PEG-silane moieties were removed by rinsing the chip in ethanol and DI water, sequentially.…”

Rational Fabrication of Nano-to-Microsphere Polycrystalline Opals Using Slope Self-Assembly

“…Self-assembly has continuously attracted interest as a bottom-up nanofabrication technique capable of producing structures with unique properties without the need for manual intervention to guide precise structure formation. , In particular, colloidal self-assembly has been extensively studied and used to fabricate 2D and 3D crystalline arrays of spheres, with diameters ranging from nanometers to tens of microns . These structures, often referred to as opals, have been used, either as-fabricated or as a template, in a wide range of applications including optical coatings and optoelectronics, − micro thermo-fluidic systems, − electrochemical systems, − sensors, , molecular printing, − and lithography masks , (Figure ). In these applications, the properties of the resulting structures are dependent on the characteristics of the opal crystal, including its order, porosity, and particle size .…”

“…Self-assembled opals have been used as-fabricated or as templates for porous materials in a wide range of applications including (a) optical coatings, − (b) coatings to enhance boiling heat transfer, , (c) high power density electrodes, − (d) molecular and ionic sensors, , (e) molecular printing, − and (f) lithography masks. , Depending on the application, the opal properties, such as the colloid size, need to be carefully chosen to optimize the device-level performance.…”