L-Homocysteine has been an amino acid intermediate of interest for over 20 years due to its implication in various adverse health conditions, including cardiovascular disease. Here, we report the first in vitro selection and application of high affinity aptamers for the target L-homocysteine. Two novel aptamer sequences were selected following 8 rounds of selection that displayed high affinity binding and selectivity to homocysteine compared to other amino acids. One of the selected aptamers, Hcy 8 (K D ¼ 600 AE 300 nM), was used to develop a gold-nanoparticle biosensor capable of sensitive and selective homocysteine detection in human serum, with a limit of detection of 0.5 mM and a linear range of 0.5-3.0 mM. This biosensor allows rapid detection of free homocysteine in human serum samples at low cost, with little preparation time and could be adapted to be part of a point-of-care screening method.

BackgroundTraditional PCR methods for forensic STR genotyping require approximately 2.5 to 4 hours to complete, contributing a significant portion of the time required to process forensic DNA samples. The purpose of this study was to develop and validate a fast PCR protocol that enabled amplification of the 16 loci targeted by the AmpFℓSTR® Identifiler® primer set, allowing decreased cycling times.MethodsFast PCR conditions were achieved by substituting the traditional Taq polymerase for SpeedSTAR™ HS DNA polymerase which is designed for fast PCR, by upgrading to a thermal cycler with faster temperature ramping rates and by modifying cycling parameters (less time at each temperature) and adopting a two-step PCR approach.ResultsThe total time required for the optimized protocol is 26 min. A total of 147 forensically relevant DNA samples were amplified using the fast PCR protocol for Identifiler. Heterozygote peak height ratios were not affected by fast PCR conditions, and full profiles were generated for single-source DNA amounts between 0.125 ng and 2.0 ng. Individual loci in profiles produced with the fast PCR protocol exhibited average n-4 stutter percentages ranging from 2.5 ± 0.9% (THO1) to 9.9 ± 2.7% (D2S1338). No increase in non-adenylation or other amplification artefacts was observed. Minor contributor alleles in two-person DNA mixtures were reliably discerned. Low level cross-reactivity (monomorphic peaks) was observed with some domestic animal DNA.ConclusionsThe fast PCR protocol presented offers a feasible alternative to current amplification methods and could aid in reducing the overall time in STR profile production or could be incorporated into a fast STR genotyping procedure for time-sensitive situations.

“Smart” materials are an emerging category of multifunctional materials with physical or chemical properties that can be controllably altered in response to an external stimulus. By combining the standard properties of the advanced material with the unique ability to recognize and adapt in response to a change in their environment, these materials are finding applications in areas such as sensing and drug delivery. While the majority of these materials are responsive to physical or chemical changes, a particularly exciting area of research seeks to develop smart materials that are sensitive to specific molecular or biomolecular stimuli. These systems require the integration of a molecular recognition probe specific to the target molecule of interest. The ease of synthesis and labeling, low cost, and stability of DNA aptamers make them uniquely suited to effectively serve as molecular recognition probes in novel smart material systems. This review will highlight current work in the area of aptamer-based smart materials and prospects for their future applications.

The results indicate that comparable concentration results are obtained from DBS and whole blood samples within the same laboratory, indicating that changing between the two matrices is viable. The comparable results of DBS samples analyzed at two laboratories using different analytical methodologies demonstrate that the technique is robust and transferable.

Aptamers are short, single-stranded nucleic acids that fold into well-defined three dimensional (3D) structures that allow for binding to a target molecule with affinities and specificities that can rival or in some cases exceed those of antibodies. The compatibility of aptamers with nanostructures such as thin films, in combination with their affinity, selectivity, and conformational changes upon target interaction, could set the foundation for the development of novel smart materials. In this study, the development of a biocompatible aptamer-polyelectrolyte film system was investigated using a layer-by-layer approach. Using fluorescence microscopy, we demonstrated the ability of the sulforhodamine B aptamer to bind its cognate target while sequestered in a chitosan-hyaluronan film matrix. Studies using Ultraviolet-visible (UV-Vis) spectrophotometry also suggest that deposition conditions such as rinsing time and volume play a strong role in the internal film interactions and growth mechanisms of chitosan-hyaluronan films. The continued study and development of aptamer-functionalized thin films provides endless new opportunities for novel smart materials and has the potential to revolutionize the field of controlled release.