Aptamer-based colorimetric and lateral flow assay approaches for the detection of toxic metal ions, thallium(i) and lead(ii).

Thallium(i) and lead(ii) ions are heavy metals and extremely toxic. These metals are environmental pollutants, posing a severe risk to the environment and human health. In this study, two approaches were examined using aptamer and nanomaterial-based conjugates for thallium and lead detection. The first approach utilized an in-solution adsorption-desorption approach to develop colorimetric aptasensors for the detection of thallium(i) and lead(ii) using gold or silver nanoparticles. The second approach was the development of lateral flow assays, and their performance was tested with thallium (limit of detection is 7.4 µM) and lead ion (limit of detection is 6.6 nM) spiked into real samples. The approaches assessed are rapid, inexpensive, and time efficient with the potential to become the basis for future biosensor devices.

An Integrated System for Fetal Scalp Visualization, Blood Collection and Analysis.

KEY MESSAGE: The new NB scope aids in better visualization of the scalp and blood collection and analysis at bed side. OBJECTIVE: Caesarean section rates and inherent complications are on the rise all over the world. One way to avoid a caesarean is to measure fetal scalp blood lactate levels. The methods available to visualize fetal scalp, obtain the blood sample and perform the blood test are separate, cumbersome and expensive, needing a certain level of expertise. We propose a device that incorporates all the steps of obtaining a fetal scalp blood lactate into one sleek, easy to use device. METHODS: The initial design, 3-D print and was tried on mannequin. After ethics committee approval, the prototype was experimented on patients in labour with singleton live fetus in cephalic presentation with no evidence of distress. RESULTS: There were (n = 9) patients recruited. There were (n = 5) primigravida and (n = 4) multigravida all of whom were in active labour. Parity did not seem to influence ease of instrumentation. Of the (n = 9) mothers (n = 2) had meconium-stained liquor and the rest (n = 7) had clear liquor, meconium-stained liquor did not affect visualization. The mean time taken to collect the sample was 184.11(± 33.04) seconds. CONCLUSION: The Neeraj-Bhaskar (NB) scope is an easy to use, affordable device that can be used time and again to decide on cases where emergency caesarean section can be avoided due to fetal distress.

Correction to: Comparison of turn-on and ratiometric fluorescent G-quadruplex aptasensor approaches for the detection of ATP.

Regrettably, before online publication the figure of Scheme 2 has been pasted twice as Scheme 1.

Comparison of turn-on and ratiometric fluorescent G-quadruplex aptasensor approaches for the detection of ATP.

Two fluorescent aptasensor methods were developed for the detection of ATP in biochemical systems. The first method consisted of a label-free fluorescent "turn-on" approach using a guanine-rich ATP aptamer sequence and the DNA-binding agent berberine complex. In the presence of ATP, the ATP preferentially binds with its aptamer and conformationally changes into a G-quadruplex structure. The association of berberine with the G-quadruplex results in the enhancement of the fluorescence signal of the former. The detection limit of ATP was found to be 3.5 µM. Fluorescence, circular dichroism and melting temperature (Tm) experiments were carried out to confirm the binding specificity and structural changes. The second method employs the ratiometric fluorescent approach based on the Forster resonance energy transfer (FRET) for the detection of ATP using berberine along with a quencher (AuNRs, AgNPs) and a fluorophore (red quantum dots (RQDs), carbon dots (CDs)) labeled at 5' and 3' termini of the ATP-binding aptamer sequence. Upon addition of ATP and berberine, ATP specifically binds with its aptamer leading to the formation of G-quadruplex, and similarly, berberine also binds to the G-quadruplex. This leads to an enhancement of fluorescence of berberine while that of RQD and CDs were significantly quenched via FRET. The respective detection limits calculated were 3.6 µM and 3.8 µM, indicating these fluorescent aptasensor methods may be used for a wide variety of small molecules. Graphical abstract.

Label-free aptasensors based on fluorescent screening assays for the detection of Salmonella typhimurium.

We report two label-free fluorescent aptasensor methods for the detection of S. typhimurium. In the first method, we have used a ''turn off'' approach in which the aptamer is first intercalated with SYBR Green I (SG), leading to a greatly enhanced fluorescence signal. The addition of S. typhimurium (approximately 1530-96938 CFU/mL), which specifically binds with its aptamer and releases SG, leads to a linear decrease in fluorescence intensity. The lowest detection limit achieved with this approach was in the range of 733 CFU/mL. In the second method, a ''turn on'' approach was designed for S. typhimurium through the Förster resonance energy transfer (FRET) between Rhodamine B (RB) and gold nanoparticles (AuNPs). When the aptamer and AuNPs were mixed with RB, the fluorescence of RB was significantly quenched via FRET. The aptamer adsorbs to the AuNP surface to protect them from salt-induced aggregation, which leads to the fluorescence quenching of RB in presence of AuNPs. Upon the addition of S. typhimurium, S. typhimurium specifically binds with its aptamer and loses the capability to stabilize AuNPs. Thus, the salt easily induces the aggregation of AuNPs, resulting in the fluorescence recovery of the quenched RB. S. typhimurium concentrations ranging from 1530 to 96938 CFU/mL with the detection limit of 464 CFU/mL was achieved with this methodology. Given these data, some insights into the molecular interactions between the aptamer and the bacterial target are provided. These aptasensor methods also may be adapted for the detection of a wide variety of targets.

Engineering challenges and the future prospects of transcatheter mitral valve replacement technologies: a comprehensive review of case studies.

INTRODUCTION: Catheter based Interventional procedures have become an indispensable treatment option for patients contraindicated for surgical heart valve replacement . The broad spectrum of disease that affect the mitral valve have increased the need for a transcatheter mitral valve replacement (TMVR) device. As complex as the mitral valve anatomy is, so are challenges in the development of a TMVR device. Areas covered: This review article analyses the challenges in the development of the TMVR device from an engineering perspective of material and device design. The major sections in this paper discusses the engineering challenges in the development of TMVR device, material & design considerations, surface coating, present and future of TMVR, delivery catheter specifications and commercial prospects of the TMVR. This article highlights the current status in the development of each of the devices based on the outcome clinical trials and case studies. The literature analysis was carried out using the keywords search. Expert commentary: This section concludes with the need for collaborative efforts from the medical and engineering expertise for the successful development of TMVR device. Overcoming the anatomical challenges with engineering innovations would create new frontier in TMVR technologies.

Enhancing professionalism among engineering students through involvements in technical societies.

A student chapter can be considered to be a miniature enterprise; however without the latter's major financial risks. Involvement in the student chapter of a professional society like IEEE at undergraduate level plays a pivotal role in the overall professional development of the student by keeping the students informed about the various career possibilities. A student chapter shapes the hitherto naive students into industry ready professionals and to suitable candidates for some of the best grad schools worldwide. This assertion has been discussed in-depth taking the example of IEEE EMBS Student Branch chapter of VIT University. It has been described how the entire process, - starting from inception of an idea to its materialization in to an activity, has shaped the volunteers and participants into better professionals.

Interaction of DNA minor groove binder Hoechst 33258 with bovine serum albumin.

Hoechst 33258 belongs to bisbenzimidazole class of molecules having anticancer properties for their ability to inhibit topoisomerase and many other cellular processes. The aim of the present study is to understand the nature of Hoechst 33258-bovine serum albumin (BSA) binding interactions by using absorption, fluorescence and circular dichrorism (CD) measurements under simulative physiological conditions. The absorption spectra of BSA indicated the binding of Hoechst 33258 with BSA. The analysis of fluorescence data indicated the presence of both dynamic and static quenching mechanism in the binding. The associative binding constant and number of binding sites were found to be K=2.08=10(7) M(-1) and n=1.36 respectively. Biexponential fluorescence lifetime distribution of Hoechst 33258 in the presence of BSA has altered viz. tau(1) was increased significantly from 0.3 ns (60%) to 1.2 ns (13%) whereas a marginal increase in tau(2) from 3.6 ns (40%) to 4.0 ns (87%). Fluorescence anisotropy value of Hoechst 33258 has increased from 0.14 to 0.34 upon the addition of BSA. Thermodynamic parameters were also calculated using Van't Hoff plot by conducting fluorescence titration at four different temperatures, DeltaH=+102.785 kJ mol(-1), DeltaS=+490.18 kJ mol(-1), DeltaG=-491.708 kJ mol(-1). The CD spectrum of BSA revealed that the binding of Hoechst 33258 to BSA causes loss in the secondary structure but increases the thermal stability of the protein. The results indicated that hydrophobic interactions were the predominant intermolecular forces in stabilizing BSA-Hoechst 33258 complex. The possible implications of these results will be on designing better therapeutic minor groove binding drug molecules.