Radiosynthesis and pre-clinical evaluation of [68Ga] labeled antimicrobial peptide fragment GF-17 as a potential infection imaging PET radiotracer.

The antimicrobial peptide fragment GF-17 was synthesized in-house and conjugated with DOTA and measured molecular mass of DOTA-GF-17 conjugate was 2489 Da. The peptide conjugate was purified and labeled with [68Ga]. The best radiolabeling efficiency (95.0%) of [68Ga]DOTA-GF-17 was achieved at pH 4 with peptide conjugate amount of 20.0 nmol with 30 min of heating at 95 °C. The product remained stable for up to 3 h. The plasma protein binding and lipophilicity for [68Ga]DOTA-GF-17 were 80.98% and -3.12 respectively. The uptake studies with [68Ga]DOTA- GF-17 in S.aureus and P.aeruginosa bacterial strains demonstrated binding of 69.08% and 43.69% respectively. The animal bio-distribution and PET imaging studies were in agreement showing similar pattern for organs' tracer distribution and renal excretion. The tracer had rapid blood clearance and uptake in bone marrow and muscles was very low. The highest uptake of [68Ga]DOTA-GF-17 was observed at 45 min and 120 min in S.aureus and P.aeruginosa infections respectively. [68Ga]DOTA-GF-17 could be a promising PET tracer and holds a great scope for taking the product further to perform extensive PET studies in animal infection (using gram negative/positive strains) models to prove the diagnostic utility of this novel PET tracer for futuristic clinical applications.

Strip-based immunochromatographic assay using specific egg yolk antibodies for rapid detection of morphine in urine samples.

Using specific egg yolk antibodies (IgY), a strip-based immunochromatographic assay was developed for rapid detection of morphine in urine samples. IgY type antibody against morphine was generated by immunizing chickens with well-characterized monoacetyl morphine-protein conjugate. The antibody was labeled with gold nanoparticles and used as an immunoprobe in the dipstick format for the visual detection of morphine in urine samples. The dipstick was developed using three membranes: an application pad made of glass fiber membrane to hold the tracer, a signal generation test line on nitrocellulose membrane (detection zone) and a cellulose membrane used as an absorption pad. Analytes of interest (morphine and its analogues) added to the sample well, dissolved the labeled antibody (tracer), and the antigen-antibody complex formed was transported by the flow caused by capillary action to the test line. The color signal of test line in proportion to the morphine concentration in urine samples was measured using a detector. The developed dipstick assay format was optimized, showing the average IC(50) values of morphine as low as 9.45 ng/mL, the detection range of 1-1000 ng/mL and the lowest detection limit 2.5 ng/mL under optimal conditions of analysis. The correlation between the developed dipstick and ELISA was 0.948 in the analysis of urine samples spiked with morphine. The developed dipstick could be a highly sensitive and convenient tool for rapid detection of opiate drugs in samples with high degree of stability.