Optical Evidence for the Assembly of Sensors Based on Reduced Graphene Oxide and Polydiphenylamine for the Detection of Epidermal Growth Factor Receptor

Using Raman scattering and FTIR spectroscopy, new optical evidence for the assembly of sensors based on reduced graphene oxide (RGO) and polydiphenylamine (PDPA) for the electrochemical detection of the epidermal growth factor receptor (EGFR) are reported. The assembly process of the RGO sheets electrochemical functionalized with PDPA involves the chemical adsorption of 1,4-phenylene diisothiocyanate (PDITC), followed by an incubation with protein G in phosphate buffer (PB) solution and after that the interaction with EGFR antibodies solution. Taking into account the changes reported by Raman scattering and FTIR spectroscopy, a chemical mechanism of the assembling process for this sensor is proposed. The preliminary testing of the electrochemical activity of the sensors based on RGO and PDPA was reported by cyclic voltammetry.

Did Tim Paint a Vermeer?

Tim’s Vermeer is a recent documentary feature film following engineer and self-described non-artist Tim Jenison’s extensive efforts to “paint a Vermeer” by means of a novel optical telescope and mirror-comparator procedure. His efforts were inspired by the controversial claim that some Western painters as early as 1420 secretly built optical devices and traced passages in projected images during the execution of some of their works, thereby achieving a novel and compelling “optical look.” The authors examine the proposed telescope optics in historical perspective, the particular visual evidence adduced in support of the comparator hypothesis, and the difficulty and efficacy of the mirror-comparator procedure as revealed by an independent artist/copyist’s attempts to replicate the procedure. Specifically, the authors find that the luminance gradient along the rear wall in the duplicate painting is far from being rare, difficult, or even “impossible” to achieve as proponents claimed; in fact, such gradients appear in numerous Old Master paintings that show no ancillary evidence of having been executed with optics. There is indeed a slight bowing of a single contour in the Vermeer original, which one would normally expect to be straight; however, the optical explanation for this bowing implies that numerous other lines would be similarly bowed, but in fact all are straight. The proposed method does not explain some of the most compelling “optical” evidence in Vermeer’s works such as the small disk-shaped highlights, which appear like the blur spots that arise in an out-of-focus projected image. Likewise, the comparator-based explanations for the presence of pinprick holes at central vanishing points and the presence of underdrawings and pentimenti in several of Vermeer’s works have more plausible non-optical explanations. Finally, an independent experimental attempt to replicate the procedure fails overall to provide support for the telescope claim. In light of these considerations and evidence, the authors conclude that it is extremely unlikely that Vermeer used the proposed mirror-comparator procedure.