Polymer brushes for immobilizing molecules to a surface and having water-soluble or water-dispersible segments therein and probes bonded thereto

Abstract

Sensors for determining the presence and concentration of bio-molecules in a biological sample are provided in the form of polymer brushes, which comprise a substrate having a surface that is modified with a water-dispersible or water-soluble polymer segment having functional groups that bind probes. The method of synthesis of such sensors preferably includes use of controlled free radical polymerization techniques, and in particular the use of an iniferter initiator, which allows for controlled architecture polymers to modify the surface of the substrate. In this manner functional groups in the polymer chain are removed from the surface, which allows for solution chemistry to be more realistically reproduced with the benefits of a solid bound probe.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a continuation of, and claims priority from, U.S. application Ser. No. 09 / 911,683 (filed Jul. 24, 2001), which is a continuation of, and claims priority from, U.S. application Ser. No. 09 / 609,461 (filed Jul. 3, 2000), which is a continuation-in-part of U.S. application Ser. Nos. 09 / 347,606, 09 / 347,607, 09 / 347,608 and 09 / 347,609 (all of which were filed on Jul. 2, 1999 and which are now abandoned) and which claims the benefit of priority therefrom as well as from U.S. Provisional Application Nos. 60 / 146,936 (filed Jul. 31, 1999) and 60 / 177,879 (filed Jan. 24, 2000). All of these related applications are incorporated by reference herein.BACKGROUND [0002] This invention relates to a polymer brush that features a polymer layer on a substrate surface, the polymer layer being composed of a number of polymer chains each of which include a water-soluble or water-dispersible segment having two termini, one terminus being free ...

AI Technical Summary

Benefits of technology

[0012] This invention provides the advantage of careful control of the identity, surface grafting density or spacing, and molecular architecture of the functionalized polymer chains. Accordingly, use of this invention provides the ability to prepare a functionalized surface that, in terms relative to the accessibility of surface-bound functional groups to probe molecules, and probe molecules to biological sample components, approximates that of an aqueous solution. At the same time, the probes are tethered to the surface, thereby facilitating analysis following contact with a biological sample.

[0013] This invention provides functionalities that bind probes, which are not attached to a flat surface. This means that solution chemistry is more closely simulated, surface effects are reduced, and as a result the sensors of this invention provide increased sensitivity, increased signal, increased signal to noise ratios and increased dynamic range.

[0015] Overall sensitivity of the sensor is also improved, it is believed, due to the spacing of the functional groups that bind the probes from the surface of the substrate. In other words, increased sensitivity has been observed, which is believed to result from the fact that the functional groups that bind the probes are now attached to a polymer chain thereby distancing the probes (and hence the related biochemistry) from the surface of the substrate, reducing, if not completely eliminating, surface effects.

Problems solved by technology

Attaching probe molecules to surfaces is often difficult because the surfaces lack functional groups that are uniquely reactive in an aqueous system or are readily accessible to the probe molecules as a result of factors such as surface crowding or steric hindrance.

This problem becomes particularly acute as the number of functional groups per unit area of surface increases.

Here, too, factors such as steric hindrance may hamper accessibility.

Molecular crowding (i.e., density) becomes a critical issue as well, particularly in systems where fluorescence quenching can be an issue.

The resulting brushes, however, were not water-soluble or water-dispersible and thus were not suitable for applications involving aqueous samples such as biological samples.

Additionally, Husseman et al. fail to address the importance of controlling the grafting density of, or spacing between, the polymer chains attached to the substrate surface, in order to optimize both the number of probes which may be attached for a given application, as well the efficiency of those probes, once attached, to interact with the target molecules.

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