RESUMEN
Emerging ion transport dynamics with memory effects at nanoscale solution-substrate interfaces offers a unique opportunity to overcome the bottlenecks in traditional computational architectures, trade-offs in selectivity and throughput in separation, and electrochemical energy conversions. Negative differential resistance (NDR), a decrease in conductance with increasing potential, constitutes a new function from the perspective of time-dependent instead of steady-state nanoscale electrokinetic ion transport but remains unexplored in ionotronics to develop higher-order complexity and advanced capabilities. Herein, NDR is introduced in hysteretic and rectified ion transport through single conical nanopipettes (NPs) as ionic memristors. Deterministic and chaotic behaviors are controlled via an electric field as the sole stimulus. The NDR arises fundamentally from the availability and redistribution of the ionic charges during the hysteretic and rectified transport at asymmetric nanointerfaces. The elucidated mechanism is generalizable, and the drastically simplified operations enable tunable state-switching dynamics with higher-order complexity besides the first-order synaptic functions in multiple excitatory and inhibitory states.
RESUMEN
Quantification of circulating microRNAs (miRNAs) or viral RNAs is of great significance because of their broad relevance to human health. Currently, quantitative reverse transcription polymerase chain reaction (qRT-PCR), as well as microarray and gene sequencing, are considered mainstream techniques for miRNA identification and quantitation and the gold standard for SARS-CoV2 detection in the COVID-19 pandemic. However, these laboratory techniques are challenged by the low levels and wide dynamic range (from aM to nM) of miRNAs in a physiological sample, as well as the difficulty in the implementation in point-of-care settings. Here, we describe a one-step label-free electrochemical sensing technique by assembling self-folded multi-stem DNA-redox probe structure on gold microelectrodes and introducing a reductant, tris(2-carboxyethyl) phosphine hydrochloride (TCEP), in the detection buffer solution to achieve ultrasensitive detection with a detection limit of 0.1 fM that can be further improved if needed.
Asunto(s)
Técnicas Biosensibles , COVID-19 , Nanopartículas del Metal , MicroARNs , Humanos , MicroARNs/análisis , Microelectrodos , ARN Viral , Pandemias , Límite de Detección , SARS-CoV-2 , Técnicas Electroquímicas/métodos , Sondas de ADN , Técnicas Biosensibles/métodos , Nanopartículas del Metal/químicaRESUMEN
Living kidney donation from donors <18 yr of age is uncommon. The majority of donations from adolescents took place several decades ago providing a unique opportunity to study true long-term consequences of donation. We compared survival, renal outcomes, and rates of hypertension and diabetes among 42 adolescent donors and matched older controls. Adolescent donors were matched with donors 18-30 yr on the following: gender, relation to the recipient, BMI at donation, eGFR at donation, and year of donation. After a mean follow-up of 31.8 ± 8.0 yr, 94.9% of adolescent donors were alive vs. 93.8% of controls. There was no significant difference in having eGFR (MDRD) <60 mL/min/1.73 m(2) (26.1% vs. 40.9%), hypertension (35.9% vs. 39.4%), diabetes (5.1% vs. 12.5%), or proteinuria (15.4% vs. 14.1%): adolescent donors vs. controls for all comparisons. These data suggest that adolescent donors are not at a higher risk of shortened survival, hypertension, diabetes, or proteinuria. Nevertheless, they probably should donate only when other options are exhausted as they have to live with a single kidney for decades and longer follow-up is needed.