Fig 1: LSPR response for an IgG/anti-IgG model system in the opto-microfluidic platform. (a) Typical sensorgram corresponding to the detection of 1ng/mL of IgG antibody in PBS. The vertical dashed lines highlight each step of the protocol described in the text. (b) Absorption spectra of the functionalized gold nanospikes upon exposure to IgG antibody at varying concentrations. The antigen–antibody binding occurring on the surface of the Au nanospikes increases the local RI, causing the red shift of the LSPR peak position (see the black arrow). (c) LSPR response at different IgG antibody concentrations. Each data point corresponds to averaged data from triplicate experiments, with the error bars denoting the standard deviation. (d) Specificity test against BSA (100μg/mL), IL-6 (10μg/mL), CRP (1μg/mL) and a mixture of these analytes at 1μg/mL. All these samples produce negligible wavelength shifts falling under the experimental error. However, when 1ng/mL of anti-IgG is added to the mixture, the wavelength shift is similar to that measured in the PBS with 1ng/mL of anti-IgG.
Fig 2: Results of the realized CRP biosensor platform. (A) Measured reduction currents during read-out for different exemplary CRP concentrations in undiluted human blood serum. (B) Calibration curve obtained by plotting the measured reduction currents after 20 s vs. CRP concentration. Mean values and standard deviations are shown (n = 3). The red dashed line shows the best fit using a nonlinear sigmoidal model. The gray dashed line depicts the current value at 0 ng/mL CRP in undiluted serum.
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