Methods and devices for detection and measurement of analytes
Sensors for target entities having functionalized thereon, at least one aptamer specific to the target entity, and methods of making and using the same are described for use in glycated protein monitoring and/or biomarkers.
1. A method for forming a sensor for one or more analytes, comprising:
a) adsorbing binary components comprised of 3-mercaptopropionic acid (MPA) and (1-mercapto-11-undecyl)tri(ethylene glycol) (PEG3) on a substrate;
b) reductively desorbing MPA from the substrate of step a);
c) forming a dithiobis-N-succinimidyl propionate (DTSP) layer on the substrate of step b);
d) immobilizing at least one type of aptamer on the substrate of step c); and,
e) removing unbound aptamer from the PEG3 on the substrate of step d), thus leaving aptamer attached to the DTSP layer of the substrate.
2. The method of claim 1 ,
wherein, in step a) the substrate is a gold surface substrate in an ethanol solution;
wherein, in step b) the MPA is desorbed from the substrate of step a) in a 0.5 M KOH solution, wherein the adsorbed MPA in a phase-separated binary self-assembled monolayer (SAM) of MPA and PEG3 is selectively reduced by applying a potential of −1.2 V for 30 min to the solution; and,
wherein, in step c) the DTSP is formed by immersing the substrate of step b) having the PEG3 layer thereon, in a 1 mM DTSP solution to form the DTSP layer thereon.
3. The method of claim 1 , wherein the analyte comprises a glycated form of a protein in blood.
4. The method of claim 3 , comprising determining a fraction of a specific glycated protein from a total serum protein level.
5. The method of claim 1 , wherein the analyte comprises one or more of: human hemoglobin, albumin, including human serum albumin (HSA), immunoglobulin G (IgG), immunoglobulin M (IgM), fibrinogen, and/or fragments thereof, the analyte being in glycated or non-glycated forms.
6. The method of claim 1 , wherein the analytes comprise at least a first analyte having a different half-life from at least a second analyte, and the method further comprises quantifying the first and second analytes to provide a retrospective judgment regarding levels of the first and second analytes over one or more time periods.
7. The method of claim 1 , wherein the analytes comprise at least a first analyte, at least a second analyte, and at least a third analyte, each of the first, second, and third analytes having different half-lives; the method further comprising: quantifying the first, second, and third analytes to provide a retrospective judgment regarding levels of the first, second, and third analytes over one or more time periods.
8. The method of claim 7 , wherein the first analyte is comprised of hemoglobin, the second analyte is comprised of IgM, and the third analyte is comprised of albumin; wherein one or more of the first analyte, the second analyte or the third analyte is present in a glycated form or a non-glycated form.
9. The method of claim 1 , the method further comprising: contacting the sensor with a blood sample; determining an amount of a glycated form of the analyte in the blood; and correlating the amount of the analyte present in the blood sample in the glycated form to a control level for a given time frame.
10. The method of claim 9 , wherein the amount of the glycated form of the protein is determined using surface plasmon resonance (SPR).