High-Throughput Optical Sensing Immunoassays on Smartphone

We present an optical sensing platform on a smartphone for high-throughput screening immunoassays. For the first time, a designed microprism array is utilized to achieve a one-time screening of 64 samples. To demonstrate the capability and the reliability of this optical sensing platform on smartphone, human interleukin 6 (IL-6) protein and six types of plant viruses are immunoassayed. The ability of quantification is shown by a sigmoidal dose–response curve fitting to analyze IL-6 protein. The accuracy in measuring the concentrations of IL-6 protein achieves 99.1%. On the other hand, to validate on-field immunoassays by our device, a total of 1030 samples are assayed using three immunoassay methods to detect six types of plant viruses. The accuracy is up to 96.2–99.9%; in addition, there is a high degree of agreement with lab instruments. The total cost for this high-throughput optical screening platform is ∼$50 USD. The reading time is only 2 s for 64 samples. The size is just as big as a portable hard drive. Our optical sensing platform on the smartphone offers a route toward in situ high-throughput screening immunoassays for viruses, pathogens, biomarkers, and toxins by decentralizing laboratory tests. With this mobile point-of-care optical platform, the spread of disease can be timely stopped within a very short turnaround time

Smartphone Optosensing Platform Using a DVD Grating to Detect Neurotoxins

We present a smartphone optosensing platform (SOP) using a digital versatile disc (DVD) diffraction grating for rapid in-field detecting neurotoxins. The smartphone holder and sample holder were 3D printed for the SOP. A DVD grating is demonstrated for the first time in a low-cost miniature spectrometer on the SOP to quantify the concentrations of neurotoxins. The SOP is capable of detecting optical absorbance spectra within the entire visible spectral range from 400 to 700 nm with the spectral resolution of 0.2521 nm/pixel. We demonstrated the performance of the DVD grating compared with a commercial transmission grating on the SOP and a conventional microplate reader. Paraoxon, as the selected neurotoxin model, is assayed by two types of cholinesterase (ChE) on our SOP, respectively. Integrating a DVD grating in the SOP allows quantification of paraoxon in the range from 5 nM to 25 μM with the detection limit of 2.9 nM. In addition to the low assessed detection limit at medically relevant concentrations, the performance of SOP with DVD gratings provides new avenues for a point-of-care toxin diagnosis with time and cost savings

Highly Efficient Visible Light Photocatalytic Reduction of CO₂ to Hydrocarbon Fuels by Cu-Nanoparticle Decorated Graphene Oxide

The production of renewable solar fuel through CO₂ photoreduction, namely artificial photosynthesis, has gained tremendous attention in recent times due to the limited availability of fossil-fuel resources and global climate change caused by rising anthropogenic CO₂ in the atmosphere. In this study, graphene oxide (GO) decorated with copper nanoparticles (Cu-NPs), hereafter referred to as Cu/GO, has been used to enhance photocatalytic CO₂ reduction under visible-light. A rapid one-pot microwave process was used to prepare the Cu/GO hybrids with various Cu contents. The attributes of metallic copper nanoparticles (∼4–5 nm in size) in the GO hybrid are shown to significantly enhance the photocatalytic activity of GO, primarily through the suppression of electron–hole pair recombination, further reduction of GO’s bandgap, and modification of its work function. X-ray photoemission spectroscopy studies indicate a charge transfer from GO to Cu. A strong interaction is observed between the metal content of the Cu/GO hybrids and the rates of formation and selectivity of the products. A factor of greater than 60 times enhancement in CO₂ to fuel catalytic efficiency has been demonstrated using Cu/GO-2 (10 wt % Cu) compared with that using pristine GO

Ta₂O₅‑Nanoparticle-Modified Graphite Felt As a High-Performance Electrode for a Vanadium Redox Flow Battery

To increase the electrocatalytic activity of graphite felt (GF) electrodes in vanadium redox flow batteries (VRFBs) toward the VO₂⁺/VO²⁺ redox couple, we prepared a stable, high catalytic activity and uniformly distributed hexagonal Ta₂O₅ nanoparticles on the surface of GF by varying the Ta₂O₅ content. Scanning electron microscopy (SEM) revealed the amount and distribution uniformity of the electrocatalyst on the surface of GF. It was found that the optimum amount and uniformly immobilized Ta₂O₅ nanoparticles on the GF surface provided the active sites, enhanced hydrophilicity, and electrolyte accessibility, thus remarkably improved electrochemical performance of GF. In particular, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that the Ta₂O₅-GF nanocomposite electrode with a weight percentage of 0.75 wt % of Ta₂O₅ to GF exhibited the best electrochemical activity and reversibility toward the VO₂⁺/VO²⁺ redox reaction, when compared with the other electrodes. The corresponding energy efficiency was enhanced by ∼9% at a current density of 80 mA cm^–2, as compared with untreated GF. Furthermore, the charge–discharge stability test with a 0.75 wt % Ta₂O₅-GF electrode at 80 mA cm^–2 showed that, after 100 cycles, there was no obvious attenuation of efficiencies signifying the best stability of Ta₂O₅ nanoparticles, which strongly adhered on the GF surface

The oncofetal expression profile of <i>Lin28B</i>.

<p><b>A</b>, RT-PCR showed that <i>Lin28B</i> was expressed in fetal brain and liver and in adult testis, brain, spinal cord and placenta. It was not detected in other adult tissues. <b>B</b>, RT-qPCR showed that <i>Lin28B</i> was markedly downregulated from fetal (closed bar) to adult (open bar) tissues except for the brain. <b>C</b>, RT-qPCR was performed using pairs of HCC (closed bar) and non-tumor (open bar) liver tissues. Overexpression of <i>Lin28B</i> (> 100×) was observed in 8 HCC samples (53.3%). NC, negative control; PC, positive control.</p

RT-qPCR quantification of the expression of <i>Lin28B</i> in peripheral blood monoculear cells.

<p><i>Lin28B</i> was expressed in 3 cases (5%) in the non-HCC controls (1 in healthy group and 2 in hepatitis group) and in 32 cases (33.3%) in the HCC group. (Bar: mean; Black dot: undetectable) (<b>A</b>). Patients with recurrent HCC had significantly higher expression levels of <i>Lin28B</i> than patients without recurrent HCC. (P<0.001). (Bar: mean; Black dot: undetectable) (<b>B</b>). Kaplan-Meier analysis showed that <i>Lin28B</i> was significantly associated with decreased recurrence-free survival (P<0.001) (<b>C</b>). Ratio of <i>Lin28B</i>/<i>GAPDH</i> mRNA higher than 10^-3 tended to associate with disease-specific survival (P=0.094) (<b>D</b>). <i>Lin28B</i> was significantly associated with decreased recurrence-free survival in AJCC stage I-II patients (P=0.003) (<b>E</b>) but not in AJCC stage IIIA-IVA patients (P=0.419) (<b>F</b>). <i>Lin28B</i> was significantly associated with decreased recurrence-free survival in AJCC stage I (P=0.030) (<b>G</b>) and stage II (P=0.030) patients (<b>H</b>).</p

Expression of Lin28B associated with stemness markers in HCC cells.

<p>Western blot analyses showed that Lin28B was overexpressed in captured EpCAM⁺ PLC/PRF/5 cells and Huh-7 cells but not in EpCAM⁺ HepG2 cells (A, upper panel). EpCAM⁺ PLC/PRF/5 cells demonstrated elevated levels of SOX2, Nanog and OCT4; EpCAM⁺ Huh-7 cells, SOX2 and OCT4; but EpCAM⁺ HepG2 cells, none (A, lower panel). Lin28B-pMSCV HepG2cells showed increased levels of OCT4, Nanog, SOX2 and EpCAM in western blot (<b>B</b>) and formed more spheres than vector control cells (P=0.032) (<b>C</b>). sh-Lin28B HepG2 cells showed decreased levels of OCT4, Nanog, SOX2 and EpCAM in western blot (<b>D</b>) and tended to form fewer spheres than vector control cells (P = 0.059) (<b>E</b>). sh-Lin28B PLC/PRF/5 cells and Huh-7 cells also decrease expression of stem cell markers (<b>F</b>). Lower amount of protein (40μg) was loaded in the MCS assay than that (100μg) loaded in the <i>Lin28B</i>-overexpression assay due to lower total cell number collected in MCS assay. Different viral systems were used in the experiments: retrovirus in <i>Lin28B</i> over-expression assay and lentivirus in <i>Lin28B</i> knock-down assay. Cell growth was slower when infected with lentivirus. MCS, magnetic cell sorting. Scale bar in C and E, 50 μm.</p