With the lowest concentration of 1 1 pg/mL (approximately 1.5 107 molecules/mL), there was a 0.83 cmC1 blue-shift. monitored instead of the phononic signature of the ML204 analyte, this optical platform can be replicated for other COVID variants and specific-binding-based biodetection applications. a change in luminescence ML204 (in some cases magnetic beads are attached to concentrate the sample).13?15 A modified fluorescence TNFSF8 detection method is lateral flow immunoassay, where the antibody (anti-IgM or IgG)/protein or rNA/DNA interaction is detected in a hand-held device.16 The results from the detection system presented in this work are compared with other detection techniques in Table 2. Table 1 Switch in Fermi Level and Doping with SARS-CoV-2 Spike Protein Concentrations two prominent routes: (a) charge transfer due to the relative positions of the Fermi level of graphene and the highest occupied molecular orbital (HOMO) (for electron donors) or least expensive unoccupied molecular orbital (LUMO) (for electron acceptors) levels of the interfacing molecule, and (b) dipole instant gating, which is usually amplified by the large quantum capacitance of graphene.31 This doping modifies the electronic band, which renormalizes the 2D phonons resonance conditions (Figure ?Physique11). When the electronic band is usually pushed away from the Dirac point, the absolute value of electron energy increases, leading to the decrease of the excited quasiparticles lifetime and phonon momentum. 32 This process causes a change in the 2D mode Raman shift and its scattering phononic energies, correspondingly. It is important to note that high-quality graphene is critical for this process, because defects (lattice disorders and oxy groups) lead to the combination of intervalley phonon and defect scattering forming the D peak, thus significantly suppressing the two phonon scattering of the 2D peak. ML204 Moreover, the defect sites around the graphene lattice can attract nonspecific binding, which would impact the selectivity of the biosensors. The sensing mechanism of this graphene chemeo-phononics lends simplicity to the final device construct: (a) No electrical connections are ML204 required, eliminating the need for photo- or electron-lithographic techniques;10 (b) direct measurements; (c) no electrochemical side-reactions; and (d) requires fewer reagents. The main challenge of the technique is the relative high cost of the Raman spectrometer required for detection and the data analysis, which can be mitigated for high-volume operations. In this work, graphene is usually functionalized with a CoV-2 spike RBD antibody (amino acid sequence from Arg 319 to Phe 541; polyclonal rabbit IgG, 40592-T62; Sino Biological, Inc., China) that binds specifically to the CoV-2 spike RBD protein (amino acid sequence from Arg 319 to Phe 541; ab273065; Abcam, Inc., USA) (more information is usually provided in the Supporting Information). The vicinity of the spike protein bound to the antibody prospects to a p-doping of the p-type graphene, in turn causing a blue-shift in the 2D peak. This graphene phononic device exhibits a limit of detection (LOD) of 1 1 and 3.75 fg/mL of SARS-CoV-2 antigen spike protein in PBS and in artificial saliva, respectively. Moreover, the sensor showed selectivity due to the precision of antibodyCantigen binding. It could distinguish SARS-CoV-2 spike protein from a complex mixture of other proteins and enzymes in artificial saliva as well as another member in the betacorona computer virus family: MERS-CoV spike protein. Results and Conversation The study was carried out on graphene linens produced chemical vapor deposition (CVD) on copper foil and transferred on a Si/SiO2 300 nm wafer.33 Due to the oxy and hydroxy groups around the silicon oxide surface, the graphene-on-SiO2 becomes ML204 a p-type semimetal.34 To immobilize the antibody on graphene, it is first interfaced with a 1-pyrenebutyric acid C interaction. Its amine-reactive group is usually then bound with the amino acid groups on the specific antibody of SARS-CoV-2 spike protein (Figure ?Physique11). The PBASE/graphene reaction is usually carried out in methanol for 1 h at room temperature. It is known that based on the HOMO and LUMO of the aromatic molecules and their electron-withdrawing or electron-donating groups, they can either p-dope or n-dope the graphenic materials, respectively.35 Previous work has shown that this ester and.