Single domain antibodies in the development of immunosensors for diagnostics.

Scientific advances in nanotechnology and nanoscience have enabled stability optimization and signal amplification in immunoassays by taking advantage of unique properties of nanomaterials. Biosensors based on antibodies and their fragments, also called immunosensors, are compact tools capable of providing refined antigen detection capacity. Different immunoassays that utilize these molecules for biorecognition have been used as diagnostic tools. In this regard, camelid single domain antibodies fulfill several requirements, such as nanometric size, high affinity, specificity, solubility, stability, biotechnological versatility, and low cost of production, constituting an important source for the development of immunodiagnostic devices. In this review, the main technological advances involving this specific class of molecules, as well as their major biotechnological applications will be addressed, with emphasis on their use as biosensors applied to diagnostics in human health.

Antimicrobial susceptibility assays in paper-based portable culture devices.

To detect antibiotic-resistant bacteria in areas remote from microbiology laboratories, we designed portable culture devices performing an analogue of the Kirby-Bauer disk diffusion test inside patterned papers embedded in tape. We quantified the antibiotic susceptibility of several strains of Escherichia coli and Salmonella typhimurium by measuring blue-colored zones of inhibited growth.

A comparison of the effects of PCR inhibition in quantitative PCR and forensic STR analysis.

In this paper we compare the effects of three representative PCR inhibitors using quantitative PCR (qPCR) and multiplex STR amplification in order to determine the effect of inhibitor concentration on allele dropout and to develop better ways to interpret forensic DNA data. We have used humic acid, collagen and calcium phosphate at different concentrations to evaluate the profiles of alleles inhibited in these amplifications. These data were correlated with previously obtained results from quantitative PCR including melt curve effects, efficiency changes and cycle threshold (Ct) values. Overall, the data show that there are two competing processes that result from PCR inhibition. The first process is a general loss of larger alleles. This appears to occur with all inhibitors. The second process is more sequence specific and occurs when the inhibitor binds DNA, altering the cycle threshold and the melt curve. This sequence-specific inhibition results in patterns of allele loss that occur in addition to the overall loss of larger alleles. The data demonstrate the applicability of utilizing real-time PCR results to predict the presence of certain types of PCR inhibition in STR analysis.