Biosensor with UV spectrophotometric detection

We have previously investigated the application of cellulose dialysis tubing (dialysis membrane) as a biosensor scaffold medium for the forthcoming detection with the UV spectrophotometer.  This was achieved by using small volumes of biological materials, through drying the samples on the dialysis membrane surface.  The outcomes proved the feasibility of this approach as a novel quantitative detection scheme of the bovine serum albumin (BSA) protein.  However, standard deviations seemed to be high, which revealed the necessity of optimization.  Here it is shown that the standard deviations diminish significantly, when dialysis membrane tubing is eliminated and sample is dried directly on the quartz cuvette of the spectrophotometer, in addition to performing the analysis by baseline correction of the data.  These tests were performed also with the BSA protein, for comparability with the previous work that utilized dialysis membrane as the sample application surface.  The detection limit of the current measurements was found to be 5 micromolar, corresponding to approximately 165 nanogram of protein in 0.5 microliter of the sample.  The presented approach is appropriate for the detection of the presence of protein in minute amounts of samples.  It is advantageous also due to the availability of the instrument in almost all laboratories and the presence of portable designs of the instrument as well.  In the future, applicability of the technique is aimed to be tested for DNA detection, to see the possibility of obtaining results with trace amounts of DNA, without using any sample enrichment procedures such as polymerase chain reaction.