BACKGROUND

Several nucleic acid-based diagnostic tests can be implemented by hybridizing probes to a nucleic acid sample, circularizing probes that hybridize to a target sequence, amplifying the circularized probes using rolling-circle amplification (RCA), and quantifying the number of RCA products.

In such methods, the RCA products can be quantified in a variety of different ways. For example, RCA products can, in theory, be quantified by labeling the RCA products, depositing the sample onto the surface of a glass slide, and counting the number of labeled products on the slide. However, simply placing a solution containing labeled RCA products on a glass slide, allowing the labeled RCA products to diffuse to the surface and then counting the number of labeled RCA products that have attached to the slide take several hours and not all of the labeled RCA products reach the slide and are counted. These problems can be largely solved by filtering the RCA products through a filter and then counting the number of labeled RCA products that have been captured by the filter. However, implementing such a method in a robust way can be challenging in some instances because many fluorescent labels can rapidly degrade when they are in contact with air. Further, RCA products can move around if the filter is wet. These challenges can make it difficult to implement such methods in a high throughput way, particularly when the sample has to be physically moved (e.g., inverted or rotated), the analysis cannot always be performed immediately, or a sample needs to be re-analyzed.

This disclosure is believed to provide a solution to these problems.

SUMMARY

This disclosure provides, among other things, a method for processing a membrane comprising rolling circle amplification (RCA) products. In some embodiments, this method may comprise: (a) obtaining a porous capillary membrane that comprises fluorescently labeled RCA products that are in or on the membrane; (b) depositing a curable polymer onto the membrane; and (c) curing the curable polymer to encapsulate the RCA products in a solid. In some embodiments, the curable polymer may be a silicone and may be transparent in its solid form. A kit for performing the method and a composition made by the method are also provided.

Encapsulating the RCA products in a solid (as opposed to using a liquid or no liquid), is believed to “fix” the RCA products, i.e., hold the RCA products in place, on the filter and also prevent the fluorescently labeled RCA products from being oxidized (i.e., degraded) by outside air. Thus, by encapsulating the RCA products in a solid, a filter comprising labeled RCA products can be rapidly moved in multiple directions (e.g., inverted, rotated or transported) and/or stored for an extended period of time (e.g., for weeks, months or even years). The present method may therefore facilitate the analysis of RCA products in a workflow that involves rapid multi-directional movement of the filter prior to analysis (e.g., by a robot) or in a workflow in which the RCA products cannot always be quantified immediately. In addition, the present method may be used in a workflow in which a filter may need to be re-analyzed after an extended period of time.

These and other potential features and advantages may become apparent in view of the following description.

