A Photoinduced Nanoparticle Separation in Microchannels via pH-Sensitive Surface Traps

Abstract

A microfluidic surface trap was developed for capturing pH-sensitive nanoparticles via a photoinitiated proton-releasing reaction of o-nitrobenzaldehyde (o-NBA) that reduces the solution pH in microchannels. The surface trap and nanoparticles were both modified with a pH-responsive polymer—poly(N-isorpopylacylamide-co-propylacrylic acid), P(NIPAAm-co-PAA). The o-NBA-coated microchannel walls demonstrated rapid proton release upon UV light irradiation, allowing the buffered solution pH in the microchannel to decrease from 7.4 to 4.5 in 60 seconds. The low solution pH switched the polymer-modified surfaces to be more hydrophobic, which enabled the capture of the pH-sensitive nanobeads onto the trap. When a photo-mask was utilized to limit the UV irradiation to a specific channel region, we were able to restrict the particle separation to only the exposed region. By controlling UV irradiation, this technique enables not only prompt pH changes within the channel, but also the capture of target molecules at specific channel locations.

Benzoic‐Imine‐Based Physiological‐pH‐Responsive Materials for Biomedical Applications

“…prepared a surface that showed antibacterial and antithrombotic performance by PEGylation of a quaternized chitosan (QCS) cationic surface through the benzoic imine linkage . It has been demonstrated that stimuli‐responsive surfaces can provide adaptive and specific environments for cells, thereby facilitating tissue growth and regeneration . A surface that contained benzoic imine bonds exhibited a switchable cell‐adhesion property, because the pH‐responsive window lay within the pH interval, thereby offering viability for most cell lines.…”

How Can One Controllably Use of Natural ΔpH in Polyelectrolyte Multilayers?

“…By Ebara et al [98] a photoinitiated proton releasing reaction of onitrobenzaldehyde (oNBA) was suggested to have (13 of 15) 1600282 wileyonlinelibrary.com pH responsive material separation. By Ebara et al [98] a photoinitiated proton releasing reaction of onitrobenzaldehyde (oNBA) was suggested to have (13 of 15) 1600282 wileyonlinelibrary.com pH responsive material separation.…”

Photo-induced Control of Smart Polymer Systems via pH Jump Reaction

“…NBA was integrated into polydimethylsiloxane (PDMS) microchannels by presorbing NBA within the PDMS channel surface regions [18]. NBA was dissolved in acetone and flowed into the channel for less than one minute.…”

“…The channels were modified with P(NIPAAm-co-PAAc) followed by coating with NBA. The suspension of beads in PBS (pH 7.4) was injected into the channel and incubated at 37 o C, and then exposed to UV lamp through a mask for one minute [18].…”

“…The NBA-coated channel was shown to capture the pH-sensitive nanobeads onto the channel walls where pH-sensitive polymer was also grafted. Spatial control of bead traps in the channel was achieved by irradiating UV light to a limited region of the channel through a mask (Fig.3) [18]. By controlling UV irradiation, this technique enables not only prompt pH changes within the channel, but also the capture of target molecules at specific locations within the channel.…”