As new point-of-care testing (POCT) technologies proliferate, clinical lab managers and device developers will benefit from updated information and resources that are available for building new devices. An excellent resource for POCT designers is the Diagnostic Device Materials Guide, a collection of samples and data on 18 grades of fiber-based materials for diagnostic applications developed and manufactured by I.W. Tremont. Based in the US, I.W. Tremont has specialized in designing and manufacturing filtration and separation products since 1979. The company also provides expert support and product development services for advanced POCT designers. The latest edition of the Guide, which is available for free, includes samples and data on fiber-based materials with notable performance characteristics, and a detailed usage guide on implementation of D-23®, a novel plasma separation product that is relevant to development of POCT devices.
Advantages of hands-on development and responsive support
Lateral flow assays (LFA) employ a combination of complex actions and technologies, involving microfluidics, chemistry and biology. Biological fluid samples are transported by capillary action (or wicking) through the device by interacting with a series of microporous pads comprised of fiber-based filtration membranes. The pads manage basic sample handling tasks—everything from capturing and safely storing samples to processing them by conjugating bioactive particles, often in the form of antigens and antibodies, that allow specific assay results to be developed.
Glass microfiber and cellulose are commonly used for the pad materials as they are readily available and offer an affordable solution for manipulating and storing blood and other biological fluids. However, basing a precisely controlled microfluidic action on a fiber-based material raises concerns that are addressed by specific purpose-built material design elements. It helps to have a deep understanding of materials, such as basic physical specifications as well as complex chemical composition. Manufacturers, such as I.W. Tremont, can lend unique insight into these materials. It also helps to have immediate access to material samples for trial and error experimentation, a problem resolved by the samples found in the Diagnostic Device Materials Guide book. Not to be overlooked, knowledgeable support from experts in the field is invaluable for providing advice and guidance on using these specialized products.
For device developers, nothing can replace hands-on evaluation. Many resources for fiber-based filtration membrane materials exist, as do specialists who offer their time and services to assist in development, but for many device developers, nothing replaces the ability to experiment with the products in their laboratory under their unique conditions.
Example: Separating plasma from whole blood
Separating plasma from whole blood is important for the detection of biomarkers and other important analytes, especially for applications involving rapid separation from small sample volumes (5-20 µl). The D-23® Plasma Separator material product platform is a borosilicate glass microfiber available in a biochemically coated version which is enhanced using an agglutinating chemistry. This unique material yields high-quality plasma more rapidly and in greater volume than similar materials with little or no hemolysis. It is manufactured with high level lot-to-lot consistency in facilities that comply with FDA quality guidelines and may be supplied as rolls, reels, sheets, and semi-finished converted configurations in both coated and uncoated grades.
The material was developed by I.W. Tremont, a company experienced in designing and manufacturing filtration and separation products that offers practical support to device developers for selecting the optimal blood separator to accommodate their needs. The D-23® product line has been successfully commercialized in patented devices with 510K approval.
Example: Dried Blood Spot paper with excellent direct elution properties
Dried blood spot (DBS) analysis, a well-known procedure, is being used in an increasing number of applications due to advances in immunology, proteomics, and PCR. A newly improved high purity cotton-based cellulose filter paper, originally designed for the Guthrie test, has been optimized for direct elution, an emerging technology that is replacing the standard practice of punching a small disc of from the sample card and eluting sample in a solvent. The new material, CFP-DBS-v1, exhibits uniform density and formulation, making it eminently suitable for collecting protein biomarkers. Consisting of high-purity alpha cotton linter formed into a blotter paper, the product has a slightly thinner caliper which yields lower backpressure for reliable direct elution recoveries. The material holds embossing with or without heat set and converts well for incorporation into diagnostic devices. CFP-DBS-v1 is also available from I.W. Tremont.
For additional information on the D-23® and CFP-DBS-v1 materials, as well as samples with which device designers can experiment, request a free copy of the Diagnostic Device Materials Guide.