Sensitive and Specific Detection of Estrogens Featuring Doped Silicon Nanowire Arrays

Abstract

Estrogens and estrogen-mimicking compounds in the aquatic environment are known to cause negative impacts to both ecosystems and human health. In this initial proof-of-principle study, we developed a novel vertically oriented silicon nanowire (vSiNW) array-based biosensor for low-cost, highly sensitive and selective detection of estrogens. The vSiNW arrays were formed using an inexpensive and scalable metal-assisted chemical etching (MACE) process. A vSiNW array-based p−n junction diode (vSiNW-diode) transducer design for the biosensor was used and functionalized via 3aminopropyltriethoxysilane (APTES)-based silane chemistry to bond estrogen receptor-alpha (ER-α) to the surface of the vSiNWs. Following receptor conjugation, the biosensors were exposed to increasing concentrations of estradiol (E2), resulting in a well-calibrated sensor response (R 2 ≥ 0.84, 1−100 ng/mL concentration range). Fluorescence measurements quantified the distribution of estrogen receptors across the vSiNW array compared to planar Si, indicating an average of 7 times higher receptor presence on the vSiNW array surface. We tested the biosensor's target selectivity by comparing it to another estrogen (estrone [E1]) and an androgen (testosterone), where we measured a high positive electrical biosensor response after E1 exposure and a minimal response after testosterone. The regeneration capacity of the biosensor was tested following three successive rinses with phosphate buffer solution (PBS) between hormone exposure. Traditional horizontally oriented Si NW field effect transistor (hSiNW-FET)-based biosensors report electrical current changes at the nanoampere (nA) level that require bulky and expensive measurement equipment making them unsuitable for field measurements, whereas the reported vSiNW-diode biosensor exhibits current changes in the microampere (μA) range, demonstrating up to 100-fold electrical signal amplification, thus enabling sensor signal measurement using inexpensive electronics. The highly sensitive and specific vSiNW-diode biosensor developed here will enable the creation of low-cost, portable, fielddeployable biosensors that can detect estrogenic compounds in waterways in real-time.

Ordered Mesoporous Electrodes for Sensing Applications

“…The sensing platform included a second MTF electrode capped with a control aptamer, which did not react with the target, to provide a baseline and correction to drifts due to interferences. 163 Finally, field-effect transistor (FET) biosensors based on nanomaterials such as silicon nanowires 164 and graphene 165 have the potential of rapid and label-free detection of a wide range of biomarkers. Indeed, FET biosensors detect changes in the charge distribution at the surface of the transistor when biomolecules bind to the biorecognition elements on the gate electrode or the transistor channel.…”

“…Finally, field-effect transistor (FET) biosensors based on nanomaterials such as silicon nanowires and graphene have the potential of rapid and label-free detection of a wide range of biomarkers. Indeed, FET biosensors detect changes in the charge distribution at the surface of the transistor when biomolecules bind to the biorecognition elements on the gate electrode or the transistor channel .…”

Self-Sustained Quasi-1D Silicon Nanostructures for Thermoelectric Applications

“…An additional leverage to control Si NSs is their agglomeration. Si NS bundling is of paramount relevance in many applications, from antireflective layers in photovoltaic cells to sensors , and from electronics to thermoelectric devices. , Concerning thermoelectrics, tip agglomeration introduces additional electrical contact resistances that are noxious to the device efficiency . Factors affecting tip bundling were then analyzed to either reduce or enhance its extent.…”

Sensing High 17β-Estradiol Concentrations Using a Planar Microwave Sensor Integrated with a Microfluidic Channel

“…However, these techniques are time-consuming and complex, involving sample pretreatment, expensive equipment, and well-trained personnel. Recently, sensors have been designed using aptamer-based analytical methods for the detection of E2, such as electrochemical, colorimetric, fluorescent, photoelectrochemical aptasensors, and vertically oriented silicon nanowire (vSiNW) [14][15][16][17][18][19][20][21][22][23]. These sensors detect the concentration of E2 by determining E2 binding using a DNA aptamer bonded to a gold nanoparticle, 3-aminopropyltriethoxysilane (APTES), gold thin film, RhoB, and TiO 2 -BiVO 4 , and then measuring the current (I), wavelength (λ), absorbance (A), and fluorescence intensity (F).…”