Bioconjugation and stabilisation of biomolecules in biosensors

Abstract

Suitable bioconjugation strategies and stabilisation of biomolecules on electrodes is essential for the development of novel and commercially viable biosensors. In the present review, the functional groups that comprise the selectable targets for practical bioconjugation methods are discussed. We focus on describing the most common immobilisation techniques used in biosensor construction, which are classified into irreversible and reversible methods. Concerning the stability of proteins, the two main types of stability may be defined as (i) storage or shelf stability, and (ii) operational stability. Both types of stability are explained, as well as the introduction of an electrophoretic technique for predicting protein–polymer interactions. In addition, solution and dry stabilisation as well as stabilisation using the covalent immobilisation of proteins are discussed including possible factors that influence stability. Finally, the integration of nanomaterials, such as magnetic particles, with protein immobilisation is discussed in relation to protein stability studies.

Inkjet Printed Nanopatterned Aptamer‐Based Sensors for Improved Optical Detection of Foodborne Pathogens

“…The core polystyrene beads (430 nm) were decorated with gold nanoparticles with average size of 20 nm; later, the surface was modified by self‐assembling of branched polyethyleneimine (B‐PEI) to incorporate a positive net charge providing available amine groups for further aptamer conjugation. In order to achieve specificity, a truncated aptameric DNA sequence (a‐aptamer) highly specific for E. coli O157:H7 was conjugated to the fabricated particles, taking advantage of the polymeric (B‐PEI) surface with available linker points for well‐oriented conjugation . In order to mimic the peptide bonding naturally occurring during antibody conjugation, a carboxyl‐linker was functionalized to the DNA sequence and conjugated to the label particle by NHS/EDC covalent chemistry.…”

“…In order to achieve specificity, a truncated aptameric DNA sequence (a-aptamer) [26] highly specific for E. coli O157:H7 was conjugated to the fabricated particles, taking advantage of the polymeric (B-PEI) surface with available linker points for well-oriented conjugation. [32] In order to mimic the peptide bonding naturally occurring during antibody conjugation, a carboxyl-linker was functionalized to the DNA sequence and conjugated to the label particle by NHS/EDC covalent chemistry. The proper assembling was confirmed by a redshift in the UV-vis spectrum that corresponds to the B-PEI functionalization and a slight final redshift which demonstrates for the first time, the successful conjugation of a carboxyl functionalized aptameric sequence to the surface of modified AuNPs (Figure 4a) in agreement with the TEM image that presents the microstructure of the self-assembled PEI-Au-Ps particles with the controlled growth of GNPs on the core material surface ( Figure 4b).…”

Hybrid Silicon Nanowire Devices and Their Functional Diversity

“…[147] Changes in the environment properties such as pH, ionic strength, temperature, or polarity of the solvent could reverse the binding process. Molecules can be directly adsorbed on the SiNW surface through hydrogen bonding, van der Waals forces, or hydrophobic interactions, but this might not be the optimal strategy, since the long-term stability will be compromised.…”

Antibody-Electroactive Probe Conjugates Based Electrochemical Immunosensors

“…The other important issue related to immunosensors is the proper immobilization of antibodies on the surface of electrodes, which affects the sensitivity and specificity of antigen determination. There are different methods of antibody immobilization on the surface of electrodes in immunosensors, including irreversible and reversible methods [18]. The covalent binding between an antibody and the solid support is one among the most widely used.…”