# US 2026/0086062 A1 · Immobilization strategies for enhancing sensitivity of electrochemical aptamer-based sensors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2026/0086062 A1 - Document ID: US20260086062A1 - Status: Published application - Kind: A1 - Application number: 19/349,403 - Filed: 2025-10-03 - Published: 2026-03-26 - Earliest claimed: 2021-12-13 - Assignees: The Florida International University Board of Trustees - Inventors: Yi XIAO; Yingzhu LIU; Juan CANOURA - Web page: https://patentgrep.com/patent/US20260086062A1 ## CPC - G01N 27/3276: {being a hybridisation with immobilised receptors (using a FET type sensor G01N27/4145; concerning the hybridisation C12Q1/68)} - G01N 27/3277: {being a redox reaction, e.g. detection by cyclic voltammetry (voltammetry per se G01N27/42, G01N27/48)} - G01N 33/5308: {for analytes not provided for elsewhere, e.g. nucleic acids, uric acid, worms, mites} - G01N 33/5438: {Electrodes} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract The subject invention provides methods for fabricating electrochemical aptamer-based (E-AB) sensors with enhanced sensitivity, signal-to-noise ratios, LOD, and improved stability and reproducibility. The subject invention also provides methods for aptamer immobilization on the surface of the electrode, which favors sufficient spacing between aptamers at the microscale to achieve optimal target recognition, folding, and signal transduction. The E-AB sensors of the subject invention provide superior sensing regardless of the sequence or structure of the bound aptamers or the physiochemical properties of the target. ## Claims ### Claim 1 A method for improving the sensitivity and signal-to-noise ratio of an electrochemical aptamer-based (E-AB) sensor, the method comprising: providing an electrode; incubating the electrode with an immobilizing solution comprising aptamers each in a folded, target-bound state to immobilize said aptamers on the electrode, the immobilizing solution having a low ionic strength; and removing the target to have immobilized aptamers in an unfolded state. ### Claim 2 (depends on 1) The method according to claim 1, the electrode being a solid electrode or paper-based electrode, the solid electrode being made of gold, silver, copper, platinum, palladium, an alloy, or a mixture thereof. ### Claim 3 (depends on 1) The method according to claim 1, the electrode being a gold electrode. ### Claim 4 (depends on 1) The method according to claim 1, the aptamer having structure-switching functionality. ### Claim 5 (depends on 1) The method according to claim 1, the ionic strength being from about 1 mM to about 50 mM. ### Claim 6 (depends on 1) The method according to claim 1, the aptamer being modified with a redox tag at one end and a functional group at the other end; or the aptamer comprising a chemical modification at a sugar position, a phosphate position and/or a base position; or the aptamer comprising a detectable label. ### Claim 7 (depends on 6) The method according to claim 6, the redox tag being methylene blue. ### Claim 8 (depends on 6) The method according to claim 6, the functional group being a thiol, sulfide, disulfide, amide, ester, alkenyl, alkynyl, carbonyl, aldehyde, carboxylate, carboxyl, or carbonate ester group. ### Claim 9 (depends on 6) The method according to claim 6, the chemical modification at the base position being selected from 5-position pyrimidine modifications, modifications at exocyclic amines, substitution of 4-thiouridine, and substitution of 5-bromo- or 5-iodo-uracil; or the chemical modification at the sugar position being selected from 2′-amine nucleotides (2′-NH2), 2′-fluoronucleotides (2′-F), and 2′-O-methyl (2′-OMe) nucleotides. ### Claim 10 (depends on 6) The method according to claim 6, the detectable label being a fluorescent dye. ### Claim 11 (depends on 1) The method according to claim 1, the E-AB sensor having a sensitivity for target detection as low as about 10 μM. ### Claim 12 (depends on 1) The method according to claim 1, wherein the E-AB sensor can detect a target in about 5 seconds to about 60 minutes. ### Claim 13 (depends on 1) The method according to claim 1, further comprising contacting the electrode with a solution comprising a backfiller, and the backfiller being selected from 6-mercapto-1-hexanol (MCH), dithiothreitol (DTT), 9-mercapto-1-nonanol, 2-{2-[2-(2-mercaptoethoxy)ethoxy]ethoxy}ethanol, and combinations thereof. ### Claim 14 A method for fabricating an aptamer-modified electrode, the method comprising: incubating an electrode with an immobilizing solution comprising aptamer-target complexes to immobilize aptamers in a target-bound, folded state on the electrode, the immobilizing solution having a low ionic strength; incubating the electrode with a solution comprising the target and one or more backfillers; and removing the target to obtain the aptamer-modified electrode, the aptamer-modified electrode having surface-bound aptamers in an unfolded state. ### Claim 15 (depends on 14) The method according to claim 14, the electrode being a solid electrode or paper-based electrode, the solid electrode being made of gold, silver, copper, platinum, palladium, an alloy, or a mixture thereof. ### Claim 16 (depends on 14) The method according to claim 14, the ionic strength being from about 1 mM to about 50 mM. ### Claim 17 (depends on 14) The method according to claim 14, the one or more backfillers being selected from 6-mercapto-1-hexanol (MCH), dithiothreitol (DTT), 9-mercapto-1-nonanol, 2-{2-[2-(2-mercaptoethoxy)ethoxy]ethoxy}ethanol, and combinations thereof. ### Claim 18 (depends on 14) A method for detecting a cathinone in a sample, the method comprising contacting the sample with an E-AB sensor comprising an aptamer-modified electrode fabricated according to claim 14; and detecting the cathinone in the sample by measuring a current generated upon binding of the cathinone to the aptamer. ### Claim 19 (depends on 18) The method according to claim 18, the sample being a biological sample selected from blood, plasma, urine, tears, sweat, and saliva. ### Claim 20 (depends on 18) The method according to claim 18, the cathinone being selected from 3′, 4′-methylenedioxypyrovalerone (MDPV); 4′-methyl-a-pyrrolidinohexanophenone (MPHP); naphyrone; methylone; ethylone; butylone; pentylone; mephedrone; mexedrone; buphedrone; pentedrone; hexedrone; heptedrone; a-pyrrolidinopropiophenone (a-PPP); 4′-methyl-a-pyrrolidinopropiophenone (M-a-PPP); 3′,4′-methylenedioxy-a-pyrrolidinopropiophenone (MDPPP); 1-phenyl-2-(1-pyrrolidinyl)-1-pentanone (a-PVP); a-pyrrolidinohexiophenone (a-PHP); a-pyrrolidinoheptiophenone (a-PHpP, PV8); diethylpropion; pyrovalerone; dimethylcathinone; diethylcathinone; methcathinone; ethcathinone; 3-methylmethcathinone (3-MMC); 4-methyletheathinone (4-MEC); 3-chlorometheathinone (3-CMC); 4-chlorometheathinone (4-CMC); n-ethyl-nor-pentedrone (NEP); 3,4-methylenedioxy-a-pyrrolidinobutiophenone (MDPBP); 4-methyl-a-pyrrolidinobutiophenone (MEPBP); 4-fluorometheathinone (4-FMC); n-ethyl-nor-hexedrone (Hexen); n-ethyl-nor-heptedrone; 4-ethylpentedrone; 4-methyl-NEP; and n-ethyl-nor-pentylone.