DNA Aptamer Functionalized Hydrogels for Interferometric Fiber-Optic Based Continuous Monitoring of Potassium Ions

Abstract

In the present paper, we describe a potassium sensor based on DNA-aptamer functionalized hydrogel, that is capable of continuous label-free potassium ion (K+) monitoring with potential for in situ application. A hydrogel attached to the end of an optical fiber is designed with di-oligonucleotides grafted to the polymer network that may serve as network junctions in addition to the covalent crosslinks. Specific affinity toward K+ is based on exploiting a particular aptamer that exhibits conformational transition from single-stranded DNA to G-quadruplex formed by the di-oligonucleotide in the presence of K+. Integration of this aptamer into the hydrogel transforms the K+ specific conformational transition to a K+ concentration dependent deswelling of the hydrogel. High-resolution interferometry monitors changes in extent of swelling at 1 Hz and 2 nm resolution for the hydrogel matrix of 50 µm. The developed hydrogel-based biosensor displayed high selectivity for K+ ions in the concentration range up to 10 mM, in the presence of physiological concentrations of Na+. Additionally, the concentration dependent and selective K+ detection demonstrated in the artificial blood buffer environment, both at room and physiological temperatures, suggests substantial potential for practical applications such as monitoring of potassium ion concentration in blood levels in intensive care medicine.

Application of Optical Hydrogels in Environmental Sensing

“…In some studies, hydrogels with specific stimulus responsiveness were wrapped at the end of the fiber to form the interference structure. When the stimulation conditions were reached, the expansion or contraction of the hydrogel changed the wavelength of light in the fiber, [204][205][206][207] enabling target detection (Figure 17a). For example, ambient humidity could be measured by the interference structure of optical fibers wrapped with a strongly hygroscopic hydroxypropyl methylcellulose hydrogel.…”

“…For example, ambient humidity could be measured by the interference structure of optical fibers wrapped with a strongly hygroscopic hydroxypropyl methylcellulose hydrogel. [204] Additionally, fibers coated with DNA aptamermodified [205] or glucose recognition agentdoped [206,207] hydrogels enabled the detection of more complex targets, such as K + and glucose. In another method, hydrogel films with specific stimuli-responsiveness covered the surface of a metal sensor with a glass substrate to [197] c) Hydrogel microspheres immobilized with recombinant E. coli are used to detect heavy metals in water, each microsphere is wrapped in a tough semi-permeable hydrogel shell to prevent leakage of engineered bacteria.…”

Recent advances in aptamer-based biosensors for potassium detection

“…This ability to regulate the K + -specific aptamer enables the aptasensor to have higher sensitivity and adaptability in a variety of practical applications. 57–60…”

“…This ability to regulate the K + -specific aptamer enables the aptasensor to have higher sensitivity and adaptability in a variety of practical applications. [57][58][59][60] Unfortunately, a full-length review article on aptamer-based biosensors for K + detection has not been reported yet. This review offers an extensive overview of the latest developments in aptamer-based biosensors for K + detection over the past decade.…”

Biomolecule-Based Optical Metamaterials: Design and Applications

“…Pure hydrogels are composed exclusively of DNA molecules and bind through, among others, Watson-Crick base-pair interactions, enzymatic ligation, and enzymatic polymerization [ 200 ]. Some of their most recent applications are their use in capillary assays for the optical detection of short cDNA from the SARS-CoV-2 virus [ 201 ], as potassium ion monitoring sensors with potential for in situ applications [ 202 ], such as hydrogel sensors integrated with quantum dot-linked transcription factors for quantitative detection of progesterone [ 203 ], among others.…”