Manipulating and Monitoring On-Surface Biological Reactions by Light-Triggered Local pH Alterations

Abstract

Significant research efforts have been dedicated to the integration of biological species with electronic elements to yield smart bioelectronic devices. The integration of DNA, proteins, and whole living cells and tissues with electronic devices has been developed into numerous intriguing applications. In particular, the quantitative detection of biological species and monitoring of biological processes are both critical to numerous areas of medical and life sciences. Nevertheless, most current approaches merely focus on the "monitoring" of chemical processes taking place on the sensing surfaces, and little efforts have been invested in the conception of sensitive devices that can simultaneously "control" and "monitor" chemical and biological reactions by the application of on-surface reversible stimuli. Here, we demonstrate the light-controlled fine modulation of surface pH by the use of photoactive molecularly modified nanomaterials. Through the use of nanowire-based FET devices, we showed the capability of modulating the on-surface pH, by intensity-controlled light stimulus. This allowed us simultaneously and locally to control and monitor pH-sensitive biological reactions on the nanodevices surfaces, such as the local activation and inhibition of proteolytic enzymatic processes, as well as dissociation of antigen-antibody binding interactions. The demonstrated capability of locally modulating the on-surface effective pH, by a light stimuli, may be further applied in the local control of on-surface DNA hybridization/dehybridization processes, activation or inhibition of living cells processes, local switching of cellular function, local photoactivation of neuronal networks with single cell resolution and so forth.

Ultrafast high-capacity capture and release of uranium by a light-switchable nanotextured surface

“…1c, with 3-aminopropyldimethylethoxysilane (APDMES), followed by a derivative of 8-hydroxypyrene-1,3,6trisulfonic acid (HPTS), 8-acetoxy-pyrene-1,3,6-trisulfonyl chloride. 29,49 Frequently applied as a light-triggered source of protons in various studies, 29,48,49,51,[57][58][59] HPTS has a pK a of $7.3 at the ground state and is exceptionally more acidic when photoexcited, with pK a as low as $0.4. Previous uorescence experiments veried that the photoactivated pH decrease is conned to the surface, depending on the light intensity of the source.…”

“…These materials have been widely studied in several applications, [46][47][48][49][50] including the light-triggered pH drop caused by photoactivation of photoacid molecules applied in silicon nanowire-based eld-effect transistor (SiNW-FET) devices for the on-surface modulation of protein affinity to an antibody. 51 The resulting controlled on-surface pH drop immediately transforms the highly receptive binding surface into a highly reective antibinding surface, due to the dissociation of antibody-antigen pairs. This light-triggered step transforms the SiNPs' capturing surface into a fast-releasing unit, thus exploiting the best advantages from these two worlds.…”

Photoacids in biochemical applications

“…The generation of the active pepsin was controlled and monitored with a single multifunctional device. Therefore, local modulation and monitoring of surface pH by the use of a reversible photoacid was successfully achieved, offering the development of multifunctional bio-FETs [37].…”

Light-Modulated Cationic and Anionic Transport Across Protein Biopolymers

“…[21][22] This type of photoacid was also used to light-trigger several pH-responsive dynamic systems. [23][24] The second type of photoacids (or better to say photoacid generators) are molecules undergoing photoisomerization, meaning that upon light irradiation they change their chemical structure leading to a proton release. The most notable example for such photoacid, which was also used in all of the literature studies that used a photoisomerized photoacid, [9,13,15,19] is the spiropyranmerocyanine system.…”