Sensor chips are at the heart of the SPR-instrument. No wonder that there are so many designs. In addition, each of the basic sensor chips can be modified to suit the need of the moment. So delve in the applications and protocols to find your answers.

New reactive polymer for protein immobilisation on sensor surfaces
Kyprianou, Dimitris et al, Biosensors and Bioelectronics, 24: 1365-1371, (2009); Goto publication.

This article describes the synthesis of a 3D-polymer with free thioacetal groups which can react with primary amines without prior activation. In addition, the 3D-plymer contains thiol derivative groups (disulphide groups or thioethers) that promote self-assembling on a metal transducer surface like the gold surface of Sensor chip AU.

Peptide Self-Assembled Monolayers for Label-Free and Unamplified Surface Plasmon Resonance Biosensing in Crude Cell Lysate
Bolduc, Olivier R. et al, Analytical Chemistry, (2009); Goto publication.

Peptide Self-Assembled Monolayers for Label-Free and Unamplified Surface Plasmon Resonance Biosensing in Crude Cell Lysate . Short peptides, composed of polar or ionic amino acids, derived with a short organic thiol, significantly reduce nonspecific adsorption of proteins in complex biological matrices such as serum and crude cell lysate.

Recent advances in self-assembled monolayers based biomolecular electronic devices
Arya, Sunil K. et al, Biosensors and Bioelectronics, 24: 2810-2817, (2009); Goto publication.

Self-assembled monolayers (SAMs) have aroused much interest due to their potential applications in biosensors, biomolecular electronics and nanotechnology. SAMs can be formed by chemisorption of organic molecules containing groups like thiols, disulphides, amines, acids or silanes. This publication is focused on applications of organosulphur compounds (thiols) based SAMs to biomolecular electronic devices.

Yang, Q. et al, Langmuir., (2010)

Anti-nonspecific Protein Adsorption Properties of Biomimetic Glycocalyx-like Glycopolymer Layers: Effects of Glycopolymer Chain Density and Protein Size. In many cases, biomaterials surfaces are desired to be resistant to protein adsorption. A system fulfilling this task in nature is the so-called glycocalyx. There is a growing interest to mimic this glycocalyx layer to have a tool to overcome the problems with uncontrolled protein adsorption on biomaterials. In this work a glycocalyx-like layer is artificially imitated by surface-initiated atom transfer radical polymerization (ATRP) of a glycomonomer, d-gluconamidoethyl methacrylate, from a mixed self-assembled monolayer of an ATRP initiator-immobilized hydroxyl-terminated thiol and a methyl-terminated thiol as diluent.

Kausaite-Minkstimiene, A. et al, Analytical Chemistry, 82: 6401-6408, (2010); Goto publication.

A comparative study of four different antibody immobilization techniques that are suitable for modification of surface plasmon resonance (SPR) chip (SPR-chip) is reported. The evaluated SPR-chip modification techniques were (i) random immobilization of intact anti-HGH (intact-anti-HGH) via selfassembled monolayer (SAM) based on 11-mercaptoundecanoic acid (MUA); (ii) random immobilization of intactanti-HGH within carboxymethyl dextran (CMD) hydrogel by direct covalent amine coupling technique; (iii) oriented coupling of intact-anti-HGH via Fc-fragment to protein-G layer assembled on SAM consisting of MUA (MUA/pG); (iv) oriented immobilization of fragmented anti-HGH antibodies (frag-anti-HGH) via their native thiol-groups directly coupled to the gold.

Rodriguez Emmenegger, C. et al, Langmuir, 25: 6328-6333, (2009); Goto publication.

Interaction of Blood Plasma with Antifouling Surfaces. Nonspecific adsorbtion of proteins is a crucial problem in the detection of analytes in complex biological media by affinity sensors operating with label-free detection. The gold surface of SPR sensors was modified with three types of promising antifouling coatings. Self-assembled monolayers (SAMs) of alkanethiolates terminated with diethylene glycol and carboxylic groups, poly(ethylene glycol) (PEG) grafted onto the SAMs, and zwitterionic polymer brusches of poly(carboxybetaine methacrylate), poly(sulfobetaie methacrylate), and poly(phosphorylcholine methacrylate).

Ferrari, Enrico et al, Journal of Nanobiotechnology, 8: 9, (2010); Goto publication.

A new immobilization system which utilizes two monomeric polypeptides which self-assemble to produce non-covalent yet nearly irreversible complex which is stable in strong detergents, chaotropic agents, as well as in acids and alkali. The system is based on the core region of the tetra-helical bundle known as the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex.