Method and device for detection of bioavailable drug concentration

1. An electrochemical sensor comprising:

at least one electrode and a coating that surrounds the electrode, the coating comprising a structural component, a water immiscible solvent, a resistance decreasing component, and an ion exchange component,

wherein the coating selectively partitions an electrochemically active drug from a fluid or vapor sample whereby an electrochemical signal within the coating can be measured using the electrode;

wherein the coating comprises one or more of sodium tetrakis[3,5bis(trifluoromethyl) phenyl] borate (NaTFPhB) and potassium tetrakis[pentafluorophenyl] borate (KTPFPhB) as the ion exchange component; and

wherein the electrochemical sensor is a voltammetric sensor.

2. The electrochemical sensor according to claim 1 , wherein the structural component comprises a polymer selected from the group of polyvinylchloride (PVC), silicone rubber, polyurethane, (meth)acrylate polymer, polypyrrole, polythiophene, polyoctylthiophene, polyanaline, polyvinyl pyrrolidone, agarose, hydrogel, sol-gel materials, or combinations thereof.

3. The electrochemical sensor according to claim 1 , wherein the water immiscible solvent comprises 2-nitrophenyl octyl ether (o-NPOE), dioctyl sebacate (DOS), bis(2-ethylhexyl) sebacate, benzyl 2-nitrophenyl ether, bis(1-butylpentyl) adipate, bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) phthalate, 1-chloronaphthalene, chloroparaffin, 1-octanol, 1-decanol, dibutyl phthalate, dibutyl sebacate, dibutyl-dilaurate, dodecyl 2-nitrophenyl ether, or combinations thereof.

4. The electrochemical sensor according to claim 1 , wherein the resistance decreasing component is an organic salt that is not soluble in water and comprises a lipophilic cation and a lipophilic anion.

5. The electrochemical sensor according to claim 4 , wherein the lipophilic cation is selected from the group consisting of tetradodecylammonium, tetraphenylphosphonium, bis(triphenylphosphoranylidine) ammonium, dimethyldioctadecyl ammonium, hexadecyltrioctadecylammonium, methyltrioctadecylammonium, tetrahexadecylammonium, tetraoctadecylammonium, tetraoctylammonium, tridodecylmethylammonium, tris[(perfluorooctyl)propyl]ammonium, and combinations thereof.

6. The electrochemical sensor according to claim 4 , wherein the lipophilic anion is selected from the group consisting of tetraphenylborate, tetrakis(pentafluorophenyl) borate, tetrakis(4-chlorophenyl) borate, tetrakis [3,5,bis(trifluoromethyl) phenyl] borate, tetrakis(4-fluorophenyl) borate, dinonylnaphthalene sulphonate, tetrakis [3,5-bis(perfluorohexyl)phenyl]borate, tetrakis(p-tolyl)borate, tetrakis(m-tolyl)borate, tetrakis(2,4-dimethyl)borate, tetrakis(3,5-dimethylphenyl)borate, closo-dodecacarborane, undecachlorinated carborane (UCC), hexabrominated carborane (HBC), undecaiodinated carborane (UIC), undecabromocarborane, and combinations thereof.

7. The electrochemical sensor according to claim 4 , wherein the organic salt is tetradodecylammonium tetrakis(pentafluorophenyl) borate (TDDATPFPhB), bis(triphenylphosphoranylidene)ammonium tetrakis [3,5,bis (trifluoromethyl)phenyl]borate (BTPPATFPhB), tetradodecylammonium tetrakis(4-chlorophenyl)borate, tris[(perfluorooctyl)propyl]ammonium tetrakis [3,5-bis(perfluorohexyl)phenyl]borate, tetraheptylammonium tetraphenylborate, tetradodecylammonium dinonylnaphthalene sulphonate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetrakis(penta-fluorophenyl)borate, tetraphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetra-m-tolylborate, bis(triphenylphosphoranylidene)ammonium tetraphenylborate, bis(triphenyl-phosphoranylidene)ammonium tetrakis(penta-fluorophenyl)borate, bis(triphenyl-phosphoranylidene)ammonium tetrakis(4-chlorophenyl)borate, bis(triphenylphosphoranylidene) ammonium tetrakis[3,5,bis(trifluoromethyl)phenyl]borate, bis(triphenylphosphoranylidene) ammonium tetrakis(4-fluorophenyl)borate, hexadecyltri octadecylammonium tetraphenylborate, tetraoctadecylammonium tetraphenylborate, tetraoctadecylammonium tetrakis(4-chlorophenyl)borate, tetraoctadecylammonium tetraphenylborate, tetraoctadecylammonium tetrakis(4-chlorophenyl)borate, tetraoctadecylammonium tetrakis(4-fluorophenyl)borate, tetraoctylammonium tetraphenylborate, tetraoctylammonium tetrakis(pentafluorophenyl)borate, tetraoctylammonium tetrakis (4-chlorophenyl)borate, tetraoctylammonium tetrakis [3,5, bis(trifluoromethyl)phenyl]borate, tetraoctylammonium tetrakis (4-fluorophenyl)borate, tridodecylmethylammonium tetraphenylborate, tridodecylmethylammonium tetrakis(pentafluorophenyl)borate, tridodecylmethylammonium tetrakis(4-chlorophenyl)borate, tridodecylmethylammonium tetrakis [3,5,bis(trifluoromethyl)phenyl]borate, tridodecylmethylammonium tetrakis(4-fluorophenyl)borate, tridodecylmethylammonium dinonylnaphthalene sulphonate, dodecyltrimethyl ammonium dinonylnaphthalene sulphonate, tetrabutylammonium tetraphenylborate, tetrabutylammonium tetrakis(pentafluorophenyl)borate, tetrabutylammonium tetrakis(4-chlorophenyl)borate, tetrabutylammonium tetrakis(4-fluorophenyl)borate, tetrabutylammonium tetrakis [3,5,bis(trifluoromethyl)phenyl]borate, tetraphenylphosphonium tetraphenylborate, trimethylammonium undecabromocarborane (TMAUBC), and combinations thereof and combinations thereof.

8. The electrochemical sensor according to claim 1 comprising PVC as the structural component; at least one of 2-nitrophenyl octyl ether (o-NPOE), dioctyl sebacate (DOS), and 1-octanol as the water immiscible solvent; and tetradodecylammonium tetrakis(pentafluorophenyl) borate (TDDATPFPhB) or bis(triphenylphosphoranilidine) ammonium tetrakis [3,5,bis (trifluoromethyl) phenyl] borate (BTPPATFPhB) as the resistance decreasing component.

9. The electrochemical sensor according to claim 8 wherein: PVC is present in an amount of about 20 to 30 wt. percent, o-NPOE, DOS, or 1-octanol is present in an amount of about 45 to 55 wt. percent, TDDATPFPhB or BTPPATFPhB is present in an amount of about 20 to 25 wt. percent, and NaTFPhB or KTPFPhB is present in an amount of about 2 to about 4 wt. percent.

10. The electrochemical sensor according to claim 1 further comprising a biocompatibility enhancing component selected from the group consisting of nitric-oxide releasing sol-gel materials, N-(6-aminohexyl)aminopropyltrimethoxysilane, and balanced isobutyltrimethoxysilane diazeniumdiolate.

11. The electrochemical sensor according to claim 1 , wherein the lower limit of detection of the bioavailable drug in blood or serum is less than the target steady state concentration of the drug in blood or serum.

12. The electrochemical sensor according to claim 1 , wherein the drug is propofol and the sensor can detect propofol concentrations at 0.03 μM or greater.

13. The electrochemical sensor according to claim 1 , wherein the drug is propofol and the limit of detection in blood or serum is about 1 to about 2 orders of magnitude below a therapeutic range for propofol.