Electrochemical aptamer-based (E-AB) sensors are widely used in a myriad of point-of-care applications. Their rapid response, accuracy, and selectivity towards its specific target make them the new promising biorecognition elements. To date, most of the E-AB sensors uses deoxyribonucleic acid (DNA) aptamers as biological recognition element. Despite this dominance, ribonucleic acid (RNA) aptamers exhibit exquisite characteristics resulting from the presence of a 2’-OH group and non-Watson-Crick base pairing. These peculiarities allow any RNA aptamer to fold in more complex 3-D structures than their DNA counterparts, and consequently, exhibit better binding ability to small molecules. Unfortunately, RNA aptamers elements are more prone to degradation by nucleases. For this reason, RNA-based sensors are scarce. The aim of this work is to create a robust method to protect RNA E-AB sensors from nuclease-rich environments. A collagen hydrogel scaffold was used to protect the photolithographically-patterned E-AB sensor fetal bovine serum (FBS). Experimental conditions showed a 2 mg/mL hydrogel with 2 mm<sup>2</sup> pore size control the signal reduction by enzymatic degradation processes. By combining the concentration as mentioned earlier and an approximate thickness of 4 mm, results showed a 24% signal reduction attributed to the physical interaction between the hydrogel matrix and the aminoglycoside antibiotics-RNA E-AB sensor. This sensor was used to the quantification of the aminoglycoside antibiotic tobramycin (Tob) in 100% undiluted FBS serum and incubated in this matrix for approximately 60 min. RNA sensors showed no electrochemical signal degradation after this incubation period. The sensor response was fit into a Langmuir-type binding isotherm by plotting the average percentage of signal change vs. Tob concentration. The obtained binding affinity value for this RNA sensor embedded to a 4mm thick 2 mg/mL collagen was Kd = 0.12344. This effort demonstrated its usefulness protecting RNA E-AB sensors.

Integration of collagen hydrogel scaffold to enhance performance of RNA Electrochemical-Aptamer Based (E-AB) sensors

253rd National Meeting (2017)

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