Biosensor and Method

Abstract

Surface plasmon resonance (SPR) sensor biointerface with a rigid thiol linker layer and/or interaction layer ligand loading with reversible collapse and/or iron oxide nanoparticle sensor response amplification.

1 . (canceled) 
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . A method of immobilizing affinity-ligands to a hydrogel, comprising:
 (a) providing a hydrogel with coupling groups for affinity-ligands and with cross-linking groups;   (b) cross-linking said hydrogel using said cross-linking groups;   (c) introducing affinity-ligands to said cross-linked hydrogel from step (b); and   (d) reversing said cross-linking of step (b) after step (c).   
     
     
         12 . A method according to  claim 11 , wherein said coupling group and cross-linking groups are active carbonates, formed by activation of the hydrogel with N,N′-carbonyl diimidazole, or other carbonylating reagent. 
     
     
         13 . The method of  claim 11 , wherein said coupling group is selected from the group consisting of N-hydroxysuccinimide esters, reactive imidazole derivatives, epoxy, aldehyde, solfonyl chlorides, divinylsulfone, halogens, maleimide, dusulfides, thiols, and mixtures thereof. 
     
     
         14 . The method of  claim 11 , wherein the cross-linking groups are diols and are cross-linked by complex formation when exposed to molecules possessing two or more boronic acid residues. 
     
     
         15 . The method of  claim 11 , wherein the cross-linkable groups are positively and negatively charged and form ion pairs that result in cross-linking of the matrix. 
     
     
         16 . The method of  claim 15 , wherein said positively and negatively charged groups are introduced by linking of histidine to the hydrogel and where a cross-linked state is attained at pH<6.2 and a non-cross-linked state at pH>6.2. 
     
     
         17 . The method of  claim 11 , wherein reversible cross-linking is made to occur through affinity interactions between two or more molecules linked to the hydrogel, where these cross-linkages are metal chelating linkages wherein both the metal ion receptor and poly-histidine tag are linked to the matrix and where the presence of the appropriate metal ion causes complex formation, and hence, cross-linking of the hydrogel. 
     
     
         18 . The method of  claim 11 , wherein reversible cross-linking is made to occur through affinity interactions between one or more molecules linked to the hydrogel, where these cross-linkages are imidodiacetic acid and a poly-histidine tag that are both linked to the matrix and are complexed by exposure to Ni 2+  and where cross-linking is reversed by addition of any competitive metal chelating agent such as ethylenediamine tetraacetic acid or changing the pH of the local environment. 
     
     
         19 . The method of  claim 11 , wherein the ligand to be immobilized is mechanically entrapped by exposure to the activated cross-linked hydrogel and where said trapped ligand reacts with the coupling groups of the hydrogel resulting in linkage of the ligand to the hydrogel. 
     
     
         20 . The method of  claim 11 , wherein cross-linking of the hydrogel is reversed after linkage of the ligand by changing the pH of the environment. 
     
     
         21 . The method of  claim 11 , wherein cross-linking of the hydrogel is reversed after linkage of the ligand by changing the ionic strength of the solution in contact with the hydrogel. 
     
     
         22 . The method of  claim 11 , wherein cross-linking of the hydrogel is reversed after linkage of the ligand by adding an inhibitor.