Polymer Brushes on Silica Nanostructures Prepared by Aminopropylsilatrane Click Chemistry: Superior Antifouling and Biofunctionality

Abstract

In nanobiotechnology, the importance of controlling interactions between biological molecules and surfaces is paramount. In recent years, many devices based on nanostructured silicon materials have been presented, such as nanopores and nanochannels. However, there is still a clear lack of simple, reliable, and efficient protocols for preventing and controlling biomolecule adsorption in such structures. In this work, we show a simple method for passivation or selective biofunctionalization of silica, without the need for polymerization reactions or vapor-phase deposition. The surface is simply exposed stepwise to three different chemicals over the course of ∼1 h. First, the use of aminopropylsilatrane is used to create a monolayer of amines, yielding more uniform layers than conventional silanization protocols. Second, a cross-linker layer and click chemistry are used to make the surface reactive toward thiols. In the third step, thick and dense poly(ethylene glycol) brushes are prepared by a grafting-to approach. The modified surfaces are shown to be superior to existing options for silica modification, exhibiting ultralow fouling (a few ng/cm2) after exposure to crude serum. In addition, by including a fraction of biotinylated polymer end groups, the surface can be functionalized further. We show that avidin can be detected label-free from a serum solution with a selectivity (compared to nonspecific binding) of more than 98% without the need for a reference channel. Furthermore, we show that our method can passivate the interior of 150 nm × 100 nm nanochannels in silica, showing complete elimination of adsorption of a sticky fluorescent protein. Additionally, our method is shown to be compatible with modifications of solid-state nanopores in 20 nm thin silicon nitride membranes and reduces the noise in the ion current. We consider these findings highly important for the broad field of nanobiotechnology, and we believe that our method will be very useful for a great variety of surface-based sensors and analytical devices.

Smart Biointerfaces via Click Chemistry-Enabled Nanopatterning of Multiple Bioligands and DNA Force Sensors

“…23,24 Such polymers are widely used in the surface functionalization of materials for drug delivery and preventing the nonspecific binding of proteins and cells on surfaces. 25,26 These polymers can be readily affixed to surfaces through grafting-to, grafting-from techniques and via commercially available random block copolymers such as PLL-g-PEG or PAcrAm-g-PEG. 27−31 While high polymer density can be achieved through any of these strategies, the latter facilitates rapid and easy polymer deposition from aqueous solutions.…”

“…When densely assembled on surfaces, a specific class of inert, hydrophilic polymers can diminish surface energy and restrict nonspecific protein adsorption. Poly­(ethylene glycol) (PEG) and poly­(2-methyl-2-oxazoline) (PMOXA), organized in a brush-like configuration, serve as archetypal examples. , Such polymers are widely used in the surface functionalization of materials for drug delivery and preventing the nonspecific binding of proteins and cells on surfaces. , …”

Mechanochemical Coupling of Alkylsilanes to Nanoparticles for Solvent-Free and Rapid Fabrication of Superhydrophobic Materials

“…The self-cleaning property observed in lotus leaves is a prime example of this phenomenon . Over the last decade, superhydrophobic coatings have gained increasing attention due to their numerous potentials in a wide range of settings, including self-cleaning surfaces, − antifouling coatings, − and oil-water separation membranes. , The self-cleaning property of the superhydrophobic surfaces is particularly useful in applications such as solar panels and windows where the accumulation of dirt and dust can reduce their efficiency. , In antifouling applications, superhydrophobic coatings can prevent and reduce marine organisms’ attachment and biofilm growth on underwater equipment like ship hulls, which, if left untreated, can increase drag and accelerate corrosion. , Most importantly, superhydrophobic antifouling coatings can play a crucial role in reducing the initial attachment and proliferation of pathogenic bacteria on food processing equipment, medical devices, and other high-touch surfaces, thereby effectively minimizing contamination and infection, leading to significant public health and economic benefits. − …”

Nanostructured Effect on Antifouling Conducting Polymers through Interfacial Adhesive Interaction and Protein Adsorption

“…The promising antifouling materials can form a hydration layer due to the local positive and negative ion pairs on the molecular design of zwitterions, which are more effective than hydrogen bonding. However, several factors regulate the wetting ability on the interface, such as grafting density and surface roughness factor. , In this study, a surface with a regular nanopattern might induce a hydrophobic interaction on a hydrophilic CP coating by investigating the adhesive interaction. After the CP interface with periodic patterns was created, QNM mode in a liquid environment and QCM-D measurement were used to characterize the patterned surface.…”