Label-free biomarker detection from whole blood

Abstract

Label-free nanosensors can detect disease markers to provide point-of-care diagnosis that is low-cost, rapid, specific and sensitive.1-13 However, detecting these biomarkers in physiological fluid samples is difficult because of problems like biofouling and nonspecific binding, and the resulting need to use purified buffers greatly reduces the clinical relevance of these sensors. Here, we overcome this limitation by using distinct components within the sensor to perform purification and detection. A microfluidic purification chip captures multiple biomarkers simultaneously from blood samples and releases them, after washing, into purified buffer for sensing by a silicon nanoribbon detector. This two-stage approach isolates the detector from the complex environment of whole blood, and reduces its minimum required sensitivity by effectively pre-concentrating the biomarkers. We show specific and quantitative detection of two model cancer antigens from a 10 uL sample of whole blood in less than 20 minutes. This study marks the first use of label-free nanosensors with physiologic solutions, positioning this technology for rapid translation to clinical settings.

Sensing at the Surface of Graphene Field‐Effect Transistors

“…I). [74][75][76][77]80] At the end of this review, we will discuss in details that recent progresses on operating GFETs at high frequencies suggested that Debye screening can be overcome: [46] 1.…”

“…Possible routes to circumvent the Debye screening effect include short antibody design, porous polymer incorporation, and ex situ measurement in low ionic strength buffers (see Section 2.5). [74][75][76][77]80] These approaches, however, also impose limitations on the biodetection and it is highly desirable to develop a straightforward methods to overcome the Debye screening: [46] 1. without any special design or engineering of the receptor molecules and the sensor environments, and 2. in physiological conditions to facilitate in-situ, real-time biosensing. Theoretically, improved sensitivity is expected at high frequencies using a measuring strategy that overcomes the ionic screening effect.…”

Optimal signal-to-noise ratio for silicon nanowire biochemical sensors

“…1(b). The NW surfaces were functionalized with a monolayer of APTES (3-aminopropyltriethoxysilane) using the protocol described earlier, 11 which increases device stability and reduces gate leakage current in solution. A fluidic well was then glued on top of each chip for the sensing experiments, with a platinum wire used as the solution gate electrode.…”

Irreversible chemical afm-fishing for the detection of low-copied proteins

“…Таким образом, разработка новых подходов для регистрации белка с концентрационной чувствительностью (DL) на уровне DL<10 -12 М [28,33,34] является актуальным направлением в области протеомного анализа и медицинской диагностики.…”

“…Как видно, имеется существенное расхождение результатов экспериментов с данными расчётов по вышеуказанным моделям, описывающим вылавливание белка на поверхность чипа. Известны и другие примеры [33,47,48], в которых сообщается о достижении DL=2,8´10 -14 М для белка PSA при использовании нанопроводного детектора. Время регистрации белка на поверхности наноразмерного чипа при этом составило менее 20 мин.…”