CRP determination based on a novel magnetic biosensor.

The c-reactive protein (CRP) is a very significant human blood marker for inflammatory processes and is routinely determined for many clinical purposes. The widespread and well established detection method for this approximately 115 kDa hepatic protein is the high-sensitivity ELISA assay (hsCRP-ELISA) in blood serum. New approaches in medical CRP diagnosis (e.g. for CVD, inflammatory bowel disease) require rapid quantification in native matrices. A novel CRP determination method based on magnetic detection is described and tested for human blood serum, saliva and urine. The detection principle is based on two different anti-CRP antibodies (monoclonal, IgG) for CRP trapment and labelling. The linear detection range of this immunosensor ranged from 25 ng/ml to 2.5 microg/ml and is therefore much more sensitive than typical hsCRP-ELISA-assays.

Magnetic bead technology in viral RNA and DNA extraction from plasma minipools.

BACKGROUND: Nucleic acid testing (NAT) of pooled plasma samples from individual blood donations for viral nucleic acids has become widely established. Full automation of such sample processing can overcome many of the problems associated with methods used so far. STUDY DESIGN AND METHODS: In this study an automated extraction method for viral nucleic acids (parvovirus [PAV] B19 DNA, hepatitis B virus [HBV] DNA, and hepatitis A virus [HAV] RNA), starting directly from the minipool sample (n = 96, 9.6 mL), was evaluated. A magnetic separation module I (chemagic, Polymer Laboratories) in combination with the chemagic viral DNA and RNA kit special based on the use of magnetic beads was used for this purpose. More than 144 pools spiked with defined concentrations of reference material and an additional 102 pools negative for the analyte were extracted and amplified. The isolated viral nucleic acids were detected by polymerase chain reaction (PCR). RESULTS: The assays were highly specific and obtained a 95 percent detection limit of 875 IU per mL of pooled single donation for PAV B19, 260 IU per mL for HAV, and 1274 IU per mL for HBV, respectively. The crossing points showed variation coefficients from 1.49 to 2.76 percent. The turnaround time for the whole process was 3 hours. Testing of subpools to determine an infected single donation would be possible with the same general extraction method. A total of 102 unspiked minipools (96 x 100 microL per donation) were analyzed and none tested positive. CONCLUSION: The automated magnetic bead-based extraction in combination with real-time PCR detection can be used to routinely screen blood donations for viremic donors to further increase the safety of blood products. Minipools as well as subpools can be directly processed.