PicoGreen
Definition
SYBR Green I-related fluorescent dye that intercalates specifically into double-stranded DNA, used for sensitive fluorometric quantitation in plate-reader or Qubit formats.
- Related to
- SYBR Green I dye family
- Target
- Double-stranded DNA specifically
- Mechanism
- Fluorescent intercalation
- Common platforms
- Plate reader or Qubit format
Common questions
Why is PicoGreen's specificity for double-stranded DNA important in forensic quantification?+
Forensic extracts often contain single-stranded DNA fragments, degraded DNA, or RNA alongside intact double-stranded DNA. A dye that reacts only with double-stranded DNA gives a quantity estimate that better reflects the amplifiable target DNA available for STR or other PCR-based typing, rather than overestimating total nucleic acid present.
How does fluorometric quantitation with PicoGreen compare to older UV absorbance methods?+
UV absorbance at 260 nm measures all nucleic acids and many contaminants indiscriminately, which can overestimate the usable DNA amount. PicoGreen's specific binding to double-stranded DNA gives a more accurate and more sensitive measurement, which matters for the low-yield samples common in casework.
Related terms
- A260/A280 Ratio
- Absorbance ratio at 260 nm and 280 nm used to assess nucleic acid purity. Values of 1.7-1.9 indicate pure DNA; lower values...
- Cq (Cycle Threshold)
- The PCR cycle at which fluorescence crosses a defined threshold; inversely proportional to starting template concentration and used to calculate DNA quantity...
- Degradation Index (DI)
- The ratio of large-amplicon to small-amplicon Cq values in Quantifiler Trio or equivalent kits; a DI above ~3 indicates significant fragmentation of...
- InnoQuant HY
- Human-specific qPCR quantitation kit with internal PCR control, providing autosomal and Y quantitation plus degradation index; widely used in Japanese and East...
- Plexor HY
- Promega qPCR quantitation kit using isoguanosine/isocytidine quenching chemistry, providing autosomal and Y-chromosome quantitation with degradation index.
- QuantiBlot
- Human-specific slot-blot quantitation kit (Applied Biosystems) using a probe directed at the D17Z1 alpha-satellite repeat on chromosome 17.
- Quantifiler Trio
- Applied Biosystems qPCR kit reporting autosomal total DNA (small + large amplicon targets) and a Y-chromosome target, with a computed Degradation Index...