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Agricultural biosensing can aid decisions about crop health and maintenance, because crops release root exudates that can inform about their status. l-Serine has been found to be indicative of nitrogen uptake in wheat and canola. The development of a biosensor for l-serine could allow farmers to monitor crop nutrient demands more precisely. The development of robust l-serine-binding DNA aptamers is described. Because small molecules can be challenging targets for Systematic Evolution of Ligands by EXponential enrichment (SELEX), three separate DNA libraries were used for SELEX experiments. A l-homocysteine aptamer was randomized to create a starting library for a l-serine selection (randomized SELEX). The final selection rounds of the l-homocysteine selection were also used as a starting library for l-serine (redirected SELEX). Finally, an original DNA library was used (original SELEX). All three SELEX experiments produced l-serine-binding aptamers with micromolar affinity, with Red.1 aptamer having a K d of 7.9 ± 3.6 μM. Truncation improved the binding affinity to 5.2 ± 2.7 μM, and from this sequence, a Spiegelmer with improved nuclease resistance was created with a K d of 2.0 ± 0.8 μM. This l-serine-binding Spiegelmer has the affinity and stability to be incorporated into aptamer-based biosensors for agricultural applications.

This perspective examines the detection of rhizosphere biomarkers, namely, root exudates and microbial metabolites, using molecular recognition elements, such as molecularly imprinted polymers, antibodies, and aptamers. Tracking these compounds in the rhizosphere could provide valuable insight into the status of the crop and soil in a highly localized way. The outlook and potential impact of the combination of molecular recognition and other innovations, such as nanotechnology and precision agriculture, and the comparison to advances in personalized medicine are considered.

"Smart" materials are polymer systems that are able to change their physical or chemical properties in response to external stimuli in their environment. By adding a specific molecular recognition probe to a polymer, hybrid materials can be developed that retain the properties of the advanced polymer and gain the ability to respond to a specific molecular target. Aptamers are single-stranded oligonucleotides that are well-suited to serve as molecular recognition probes due to the specificity and affinity of their target recognition as well as their stability and ease of synthesis and labeling. In particular, their negatively charged backbone makes for their facile incorporation into polyelectrolyte-based materials. This article will provide a brief review of the currently reported biosensor and delivery platforms that have been reported employing aptamer-polyelectrolyte materials, as well as a detailed description of the methods used to synthesize and study films and microcapsules containing small-molecule aptamer probes., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Nucleic acid aptamers are novel molecular recognition tools that offer many advantages compared to their antibody and peptide-based counterparts. However, challenges associated with in vitro selection, characterization, and validation have limited their wide-spread use in the fields of diagnostics and therapeutics. Here, we extracted detailed information about aptamer selection experiments housed in the Aptamer Base, spanning over two decades, to perform the first parameter analysis of conditions used to identify and isolate aptamers de novo. We used information from 492 published SELEX experiments and studied the relationships between the nucleic acid library, target choice, selection methods, experimental conditions, and the affinity of the resulting aptamer candidates. Our findings highlight that the choice of target and selection template made the largest and most significant impact on the success of a de novo aptamer selection. Our results further emphasize the need for improved documentation and more thorough experimentation of SELEX criteria to determine their correlation with SELEX success.

"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.

Background: A 30-minute rule was established to limit red blood cell (RBC) exposure to uncontrolled temperatures during storage and transportation. Also, RBC units issued for transfusion should not remain at room temperature (RT) for more than 4 hours (4-hour rule). This study was aimed at determining if single or multiple RT exposures affect RBC quality and/or promote bacterial growth., Study Design and Methods: Growth and RT exposure experiments were performed in RBCs inoculated with Serratia liquefaciens and Serratia marcescens. RBCs were exposed once to RT for 5 hours (S. liquefaciens) or five times to RT for 30 minutes (S. marcescens) with periodic sampling for bacterial counts. Noncontaminated units were exposed to RT once (5 hr) or five times (30 min each) and sampled to measure in vitro quality variables. RBC core temperature was monitored using mock units with temperature loggers. Growth and RT exposure experiments were repeated three and at least six times, respectively. Statistical analysis was done using mixed-model analysis., Results: RBC core temperature ranged from 7.3 to 11.6°C during 30-minute RT exposures and the time to reach 10°C varied from 22 to 55 minutes during 5-hour RT exposures. RBC quality was preserved after single or multiple RT exposures. Increased growth of S. liquefaciens was only observed after 2 hours of continuous RT exposure. S. marcescens concentration increased significantly in multiple-exposed units compared to the controls but did not reach clinically important levels., Conclusion: Single or multiple RT exposures did not affect RBC quality but slightly promoted bacterial growth in contaminated units. The clinical significance of these results remains unclear and needs further investigation., (© 2012 American Association of Blood Banks.)

Background: To evaluate the usefulness of hypertonic saline solutions (HTS) as an alternative to mannitol in neurosurgery., Methods: Thirty patients subjected to craniotomy for supratentorial cerebral tumors were randomly divided in to three Groups: M: had mannitol 0.5 g.kg-1 as bolus at the start of skin incision, and postoperatively 0.5 g.kg-1 daily three times a day for 3 days (72 hrs); HM: had mannitol 0.25 g.kg-1 as bolus at the start of skin incision plus 3% HTS, 20 ml.h-1 intraoperatively and mannitol 0.25 g.kg-1 daily three times a day for 3 days plus HTS in the concentration of 3% in the first day and 2% and 1% the second and the third day after surgery; H: had 3% HTS 3.5 ml kg-1 as bolus at the start of skin incision plus 3% HTS, 20 ml hr-1 intraoperatively and 3% HTS, 20 ml h-1 on the first day and 2% and 1% the second and the third day after surgery. FR, MAP, ICP, CVP and diuresis were continuously monitored intraoperatively and postoperatively for 72 hrs. ICP was monitored intraoperatively until dural opening and in the postoperative period for 72 hrs at least., Results: Diuresis was increased in the first and second Group (M and HM) more than in the H Group especially in the postoperative period, but this change was not a significative one (35.31 ml.kg-1.h-1+/-4.57 and 36.56+/-3.92 vs 3.23 ml.kg-1.h-1). Mean serum Na+ values declined in the postoperative period, in Groups M and MH and remained stable in the postoperative period in the Group H (137.6+/-7 mEq.l-1 and 136.5+/-6.5 mEq.l-1 vs 139.2+/-5 mEq.l-1). Serum osmolality increased significantly in the postoperative period in group H and remained unchanged in the same period in Group M and MH. Potassium values declined significantly during the whole period in all groups but remained in a normal clinical range. CVP values decreased in Groups M and MH in the postoperative period, and increased although not significantly in the postoperative period in the Group H patients. Ht values declined significantly in all groups without differences among the groups although the reduction was greater in group H., Conclusions: HTS can safely be used in humans they obtain a reduction of ICP without reducing CVP, serum osmolality and Na+ serum values. Our data underline the possibility of their use as an alternative to mannitol in the treatment of patients scheduled for intracranial surgery, especially when multiple doses are needed.