Sensitivity is the main concern at the development of rapid test by lateral flow immunoassays. On the other hand, low limits of detection are often required at medical diagnostics and other field of analysis. To overcome this drawback, several enhancement protocols have been described. In this paper, we have selected different silver enhancement methods and one dual gold conjugation, and we critically compared the amplification produced when applied to a gold-nanoparticle based lateral flow immunoassay for the detection of prostate specific antigen (PSA). The highest amplification was obtained by using an immersion method based on a solution of silver nitrate and hydroquinone/citrate buffer in proportion 1:1. Under these conditions, the system is capable of detecting PSA within 20 min at levels as low as 0.1 ng/mL, with a 3-fold sensitivity improvement.

Introduction Purple Urine Bag Syndrome (PUBS) is a rare disorder seen in elderly persons, wherein the urinary bag and the tubing turn in to purple colour. It is usually seen in patients who are on urinary catheters for a long time. It consists of a change in the colour of the urine that turns purple in a very specific context. Case report We report the case of a paediatric female patient with Berdon Syndrome with symptoms consistent with urinary tract infection and purple urine discolouration. Urine test revealed leukocyturia and bacteriuria. Discussion Several risk factors have been proposed regarding this syndrome. Among them the commonest are female gender, advanced age, kind of diet (increased dietary tryptophan), alkaline urine and diverse situations that leads to urinary retentions which allows bacteria to work on their substrate for a longer time. Although it is a process that is not associated with gravity, recognizing it is important as treatment is simple and can minimize patient and family distress.