br Materials methods br Results and discussion The
Materials & methods
Results and discussion The comparison of BFI methods (Table 1) shows that Phosphatesmo failed to detect seminal fluid in all samples. This observation is concordant with other studies that investigated water-exposed seminal fluid stains , . The Phosphatesmo test is used to detect gc1 synthesis phosphatase (AP) in seminal fluid stains. AP is known to be water-soluble and therefore Phosphatesmo reaction was negative after water exposition. The PSA and RSID tests exhibited a similar sensitivity. PSA detection was possible in cotton cloths up to seven days and in synthetic cloths until day 3. Detection of semenogelin by the RSID test was possible for both fabrics until the third day of immersion. After presumptive testing, the residues of the stains were applied for automated DNA/RNA co-extraction. Subsequent quantification showed that nearly 100% of the RNA samples resulted in values under the detection limit (below blank) of the QuantiFluor® RNA System. Application of RNA profiling failed to detect seminal fluid in all samples. However, DNA was detectable in water-immersed samples. Overall, DNA concentrations of synthetic fiber were slightly higher than those of cotton. Yields ranged between 4.83ng/μl (day 1, synthetic fiber) and 0.02ng/μl (day 7, cotton fiber) and decreased with increasing irrigation time. Albeit the DNA reduction, amounts were still high enough to produce full and reportable profiles for all samples.
Conclusion Surprisingly, RNA-based molecular identification of seminal fluid failed in water-immersed samples. Nevertheless, conventional presumptive tests, PSA and RSID, were able to detect seminal fluid up to 3days on synthetic cloths and PSA even up to 7days on cotton cloths. While BFI appeared to be challenging, DNA typing was successful. Reportable profiles were obtained for all samples independent of fabric type or water immersion time. As analysis of water-immersed clothing in sexual assault cases seems promising, we recommend routine sampling for forensic case work.
Conflict of interest
Introduction The potential applications of nanomaterials in biology and medicine , ,  have been a hot topic of research during the last two decades. Among these, gold nanoparticles are important, as they exhibit the best compatibility with bio molecules , . Gold nanoparticles can be recognized by their intense color and their distinct surface plasmon resonance (SPR) bands , . Thus contemporary research has been strongly focussed on the development of synthetic protocols for gold nanoparticle preparation. Parallel to this, the chemistry related to their surface modification has also received considerable attention , , , , , , , . Often amine  and thiol bearing  groups have been used for surface modification of GNPs. Protein conjugated GNPs have been used in drug/DNA delivery , cell imaging  and bio staining. In the past, some groups have used surfactants for surface modification of GNPs , , , , , , , , , . However, this kind of surfactant-based modification or capping has some adverse consequences. Among surfactants, the cationic surfactant cetyltrimethylammonium bromide (CTAB) is popular for capping GNPs as it is known to be a good structure – directing agent for GNPs . However, there are quite a few reports of the cytotoxicity of CTAB , especially CTAB that remains unreacted after GNP functionalization . In view of the reported toxicity of some cationic and anionic surfactants, we were interested to see if GNPs functionalized by non-ionic surfactants may be a viable non-toxic alternative for biological studies employing GNPs. Among non-ionic surfactants, one popular surfactant is polyoxyethylene isooctyl phenyl ether (Triton X-100) . Another category of non-ionic surfactants are the polyoxyethylene sorbitan esters of fatty acids i.e. the polysorbates or the Tween surfactants . Polysorbates are an important class of non-ionic surfactants that are widely used in pharmaceuticals due to their low toxicity , . It has been previously reported that Tween-80 and Tween 20  can be used to prepare stable GNPs , .