Technical guides and protocols for lateral flow assays.
The Sensitivity Barrier Standard lateral flow assays often hit a sensitivity wall at the nanogram level. For early disease detection (e.g., HIV p24, Troponin I), you need picogram (pg/mL) sensitivity. Enhancement Strategies Using Due Bio High-Sensitivity Nitrocellulose with a slower wicking rate allows more time for antigen-antibody interaction. Combined with signal enhancement techniques like silver … Read more
Introduction: The CRISPR Diagnostics Revolution Since the discovery of Cas12a (Cpf1) collateral cleavage activity, molecular diagnostics has shifted from lab-bound PCR to field-deployable DETECTR and HOLMES assays. This comprehensive guide covers everything you need to know about setting up a high-sensitivity CRISPR-Cas12a lateral flow system. Chapter 1: Mechanism of Action Unlike Cas9, which targets DNA … Read more
Why Strips Curl Assembling lateral flow cards in uncontrolled humidity leads to membrane curling and adhesive failure. Nitrocellulose expands when wet. Ideal Conditions We manufacture Due Bio strips in a Class 100,000 cleanroom maintained at
The Spacing Rule To prevent optical cross-talk or “carry-over” between Test Line 1 and Test Line 2, we recommend a minimum spacing of 3mm. This allows the reading window to resolve distinct bands. Flow Dynamics In multiplex assays, the downstream line (T2) always sees less analyte than the upstream line (T1). Due Bio can provide … Read more
Breaking the Cell Wall Detecting viruses or bacteria in plant leaves (e.g., TMV, Xylella) requires breaking robust cellulose walls. Standard buffers often fail. High-Salt & Detergent We recommend a lysis buffer containing PVP (Polyvinylpyrrolidone) to bind plant polyphenols, along with a non-ionic detergent. Due Bio’s “Ag-Grade” sample pads are pre-buffered to neutralize acidic plant saps … Read more
The 40nm Standard For most lateral flow assays, 40nm gold is the industry standard. It offers the best balance between color intensity (optical density) and steric stability against aggregation. When to Use 20nm? Smaller 20nm particles have a higher surface-area-to-volume ratio, allowing for higher antibody loading density. This can be advantageous for competitive assays where … Read more
The Optical Interface When moving from visual readouts to digital quantification, the membrane surface texture becomes critical. Rough membranes scatter light, creating “optical noise” for reflectance readers. Surface Smoothness Due Bio Universal Strips are cast with a controlled air-side surface roughness (Ra < 2μm). This minimizes background scatter, allowing handheld readers (like those from Axxin ... Read more
The “Stringy” Sample Saliva is patient-friendly but technically difficult due to mucins causing viscosity (stringiness). This halts flow on the strip. Mucolytic Sample Pads Our Universal Strips can be paired with our proprietary “Mucin-Busting” sample pad pretreatment, which breaks down glycoprotein networks instantly, allowing saliva to flow like water.
Why Fluorescence? Europium nanobeads offer 100x higher sensitivity than colloidal gold due to Time-Resolved Fluorescence (TRF) which eliminates background noise. Membrane Autofluorescence Standard nitrocellulose glows under UV light, killing your signal. Due Bio offers a special “Low-Fluorescence” grade membrane specifically cast for TRF readers.
False Negatives at Peak Infection In acute phases (e.g., COVID-19 or CRP spikes), excess antigen can saturate antibodies, causing the Test line to fade. This “Hook Effect” is dangerous. Three-Line Architecture We recommend adding a third “Hook Line” or using Due Bio’s high-capacity sample pads to sequester excess antigen, extending the linear range of your … Read more