Lateral flow assay production
Lateral flow assays are widely used and the standard for rapid visual detection tests for point-of-care diagnostics. Increasing complexity, the integration of nanotechnologies and the determination of several analytes within one test require optimized and precise production techniques.
Non-contact dot or line printing
The piezoelectric, drop on demand dispensing of nanoliter droplet volumes provides full flexibility for the array layout in the developmental stage and a robust performance for mass production.
Lateral flow assays (LFAs) are widely used for rapid diagnostic testing and initial screening. A one-step and low-cost analysis of an analyte in a sample solution, such as pathogens, biomarkers and chemical contaminants, makes it a powerful point-of-care device without the need of trained personnel. Read how to optimize, develop and to produce LFA applying BioFluidix technology.
Nanomaterials have been widely reported in lateral flow biosensors, offering new sensing strategies based on optical or electrical detection techniques. Looking for other advantageous nanomaterials, we propose for the first time the use of iridium oxide (IV) nanoparticles in lateral flow assays for the detection of human immunoglobulin as a model protein.
Lateral flow paper-based biosensors merge as powerful tools in point-of-care diagnostics since they are cheap, portable, robust, selective, fast and easy to use. However, the sensitivity of this type of biosensors is not always as high as required, often not permitting a clear quantification. To improve the colorimetric response of standard lateral flow strips (LFs), we have applied a new enhancement strategy that increases the sensitivity of LFs based on the use of cellulose nanofibers (CNF). CNF penetrate inside the pores of LFs nitrocellulose paper, compacting the pore size only in the test line, particularly near the surface of the strip. This modification retains the bioreceptors (antibodies) close to the surface of the strips, and thus further increasing the density of selectively attached gold nanoparticles (AuNPs) in the top part of the membrane, in the test line area, only when the sample is positive.
Lateral flow strips (LFSs) are widely used for clinical diagnostics. The restricted flow control of the current designs is one challenge to the development of quantitative and highly sensitive LFSs. Here, we present a flow control for LFSs using centrifugal microfluidics. In contrast to previously presented implementations of lateral flow membranes into centrifugal microfluidic cartridges, we direct the flow radially outwards through the membrane. We control the flow using only the centrifugal force, thus it is independent of membrane wetting properties and permeability. The flow rate can be decreased and increased, enabling control of incubation times for a wide variety of samples.
The contamination in groundwater due to the presence of uranium is nowadays a subject of concern due to the severe health problems associated with renal failure, genotoxicity and cancer. [...] For the first time, we propose a portable, fast, inexpensive and sensitive paper-based biosensor able to detect in situ U(VI) in water samples: U(VI) selective gold nanoparticle-based lateral flow strips. Antibody-coated gold nanoparticles are used as labels in the proposed lateral flow system because of their biocompatibility; in addition, these nanoparticles provide high sensitivity due to their intense plasmonic effect.
The assay is intended for the detection of a model protein in human serum, that is, human immunoglobulin G, with the aim to demonstrate a virtually universal protein detection platform. Once the sample is added in the strip, the analyte is selectively captured by antibody-decorated silica beads (Ab-SiO2) onto the conjugate pad and the sample flows by capillarity throughout the strip until reaching the test line, where a sandwich-like immunocomplex takes place due to the presence of antibody-functionalized QDs (Ab-QDs) onto the test line.
A hydrophobic wax barrier (so-called a “wax gate”) combined with the use of surfactants was developed as a valving mechanism in paper-based microfluidic systems to enable the control of delays in reagent addition in the device. This mechanism allowed the delay of reagent delivery and assisted multistep analysis on microfluidic paper-based analytical device (μPADs).