Supplementary information

MaterialData

DI-Water Bio-nanoprobesArtificial

UrineNormal Urine

Conductivity(μs/cm)

1.06~1.85 54.4~73.5 34.5 4.87~15.74

pH value 5.68~5.99 5.02~5.4 7.3 6~7

Table 1: The material parameters in different solutions and frequency range of particle trapping by p-DEP/n-DEP forces.

Standard

ResistanceImpedance Device (kΩ) LCR Meter(kΩ) Error (%)

200kΩ 202.64 199.82 1.39

300kΩ 304.29 299.72 1.50

400kΩ 401.47 399.65 0.45

500kΩ 485.41 499.53 2.91

600kΩ 609.79 599.17 1.74

700kΩ 717.80 698.89 2.63

800kΩ 778.97 799.07 2.58

900kΩ 914.24 898.90 1.68

1000kΩ 1030 998.54 3.05

1100kΩ 1110 1098.00 1.08

1200kΩ 1240 1197.00 3.47

Table 2: Comparison of impedance values observed using an LCR meter and the portable impedance device.

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Fig.1. The normalized impedance variation obtained using the immunosensor is significantly higher for T24 as compared to RT4 and highlights the specificity for Gal-1 detection and (inset) western blot results showing an overexpression of Gal-1 in T24 cell lysate which is absent in RT4 cell lysate.

Fig.2. Western blot analysis shows a dark band at 14KDa which corresponds to the molecular weight of Gal-1 protein. This shows that Gal-1 protein present in T24 cell lysate specifically takes part in immunoreaction with the Gal-1 antibody to form a stable complex. The Gal-1 expression has been shown as a percentage of the total expression level. For the immunosensor chip where the immunoreaction is conducted for 30 mins

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as opposed to 60 mins using western blot, unspecified binding should be even weaker and easy to wash away.

Fig.3. (a) SEM image of the as obtained Al2O3 nanoparticles. (b) TEM image of Al2O3

nanoparticles after surface modification with silane. (c) EDX analysis of Al2O3

nanoparticles modified with silane.

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Fig.4. A schematic to illustrate the effect of the ionic strength of the solution on the charge transfer resistance (Rct) across the interdigitated microelectrodes. In low ionic strength electrolytes like PBS, the negatively charged proteins (surface charge is related to the pH of the solution and the pI of the protein) are accumulated on the microelectrode surface and prevent further charge transfer, resulting in increased impedance after immunosensing. In urine samples which have a relatively high ionic strength, the positive ions attach to the negative charges on the protein and facilitate further charge transfer across the electrodes. The effective charge transfer resistance decreases and thus the impedance decreases after immunosensing.

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Fig.5. Process of point of care testing and ability to transfer data over the cloud (a) Impedance measurement of DI water taken as an example. (b) Results are analyzed by the portable impedance device. (b) The data can be uploaded to the patients national health account on the cloud database using a personal computer. (d) The cloud database will draw a personal chart of daily recordings and warn the user and physician if abnormal responses are observed. We believe that this system will help achieve the goal of early cancer detection.

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Fig.6: The cloud database software to which the results obtained by the impedance analyzer can be directly uploaded and accessed by medical staff using a mobile phone or personal computer.

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Fig.7. EIS spectra showing the impedance and reactance response for different steps in immunosensing of T24 cell lysate (0.03125mg/ml) over a frequency range of 20 Hz-100 KHz.

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