scope:

This document gives examples of how methods of surface chemical analysis in the scope of ISO TC 201 are useful to characterize the nature of substrates used to produce biosensing devices. Successful characterization will give the opportunity for a better understanding of aspects of surface chemistries and reactions at each step of production influencing the overall performance of the final device, for example a microarray. The steps of preparation are the activation of the substrate by immobilization of linker molecules and the functionalization of the activated substrate with biomolecules required for specific biosensing, the so-called probes.

Herein, a focus is set on silane-based functionalization of glass slides, a critical production step for subsequent immobilization of probe molecules. Those probes are used for sensing of biological recognition events. The silanization process has been selected because it is one of the most popular in biosensor production today.

This document gives an overview of methods, strategies and guidance to identify possible sources of problems related to substrates, device production steps (cleaning, activation and chemical modification) and shelf-life (storage conditions and ageing). It is particularly relevant for surface chemical analysts characterizing glass-based biosensors, as well as developers or quality managers in the biosensing device production community. Based on quantitative and qualitative surface chemical analysis, strategies for identifying the cause of poor performance during device manufacturing can be developed and implemented. This document shows how far the light may shine today and possible starting points for more specific activities of ISO/TC 201 in the future, which end in standardized procedures for measurements.

No specific protocols on processing are discussed in this document. To learn more about protocols the reader is referred to specialized literature, see for example References [1] to [9].