Highly sensitive detection of cytochrome c in the NSCLC serum using a hydrophobic paper based–gold nanourchin substrate

Abstract

Cytochrome c (Cyt c) is a biomarker of early apoptosis that plays a critical role in the diagnosis and therapy of non-small cell lung cancer (NSCLC). In this work, we proposed a novel surface-enhanced Raman scattering (SERS)-based biosensor to implement the ultrasensitive detection of Cyt c in the serum of NSCLC patients. The SERS-supporting substrates based on hydrophobic filter paper were composed of gold nanourchins (GNUs) surface-functionalized with the Cyt c aptamer and the cyanine 5-labeled complementary DNA. In the existence of Cyt c, it could specifically bind to its aptamer, which leads to the detachment of complementary strands modified with Cy5 and the great weakness of SERS signal. The finite-difference time domain (FDTD) simulation showed that the excellent SERS performance of GNUs aggregation was strongly dependent on a large number of “hot spots” at the tips and between the nanogaps of aggregated GNUs. Alkyl ketene dimer (AKD) was used to make the filter paper modify its property from hydrophilic to hydrophobic, which consequently increased the density of GNUs and extended the retention time of the analyte. SERS biosensors based on hydrophobic paper exhibited prominent reproducibility and selectivity. The detection limit of Cyt c in PBS was 1.148 pg/mL, while the detection limit in human serum was 1.79 pg/mL. Moreover, the analysis of the serum samples of healthy subjects and NSCLC patients confirmed the feasibility of its clinical application. The results were consistent with enzyme-linked immunosorbent assay results. This method can be a powerful strategy for quantitative detection of extracellular Cyt c, and it is expected that the SERS-based biosensors could be applied in the practical clinical diagnoses of NSCLC.

Template-Free Synthesized Gold Nanobowls Composed with Graphene Oxide for Ultrasensitive SERS Platforms

“…The SERS performance of AuNBs is better compared to that of AuNUs, which are considered to be very good SERS supports, , making them excellent candidates for SERS applications. The large influence of the shape of the gold nanoparticles on the SERS intensity confirms that the electromagnetic factor is the most important for the SERS enhancement, though the enhancement depends clearly on the type of GO material on which gold nanoparticles are deposited.…”

Challenges and opportunities for SERS in the infrared: materials and methods

“…Colloidal nanoparticles can be delivered in situ, 89 incubated into cells or injected through tissues, 90,91 utilized for measurements in transmission conguration, 92 and immobilized on planar supports to produce arrays. [93][94][95] However, the elucidation of the mechanisms that enable anisotropic growth in colloidal sols is still subject of animated debate and research, in that several factors limit the realistic formulation of a punctual and unambiguous unied theory. While the growing accessibility of computational methods such as molecular dynamics simulations has recently aided in the exploration of otherwise inaccessible nanoscale phenomena, the real-time atomic-scale imaging and chemical mapping instrumentation that would be requisite to observe such processes directly and in their native environment is not widely accessible yet (e.g., cryogenic transmission electron microscopy, cryo-TEM), or existent.…”

“…[98][99][100] The event that breaks the symmetry of the initial isotropic gold seed is not generally attributed to CTAB. 94 For pentatwinned nanorods, this event is identied with the stochastic formation of twinning planes in the growing seed, 101 while for single-crystal nanorods, which are obtained in the presence of silver, the general belief is that silver itself is responsible for symmetry breaking. [102][103][104][105] Because symmetry breaking is an inherently stochastic process, more families of nanorods inevitably coexist in the same colloidal sol ("popcorn" mechanism), 106 thus affecting its homogeneity.…”

Cytochrome c in cancer therapy and prognosis

“…In another electrochemical biosensor, cyt c fitting into specific recognition nanocavities lowers the electrical current established between an electrolyte solution and a gold electrode [ 23 ]. In other approaches, the specific binding of cyt c to an aptamer [ 24 , 25 ] has been used for detection based on differential pulse voltammetry [ 26 ], surface-enhanced Raman scattering (SERS) [ 27 ], and fluorescence [ 28 ]. In the differential pulse voltammetry biosensor, the cyt c aptamer is immobilized on the surface of a glassy carbon electrode containing carbon nanofibers.…”

“…In the SERS biosensor, the cyt c aptamer is hybridized with a fluorescently labeled oligonucleotide attached to a gold nanoparticle immobilized on a filter paper surface. Cyt c binding to the aptamer induces its dissociation from the oligonucleotide, decreasing the intensity of the SERS signal, due to increased distance to the gold nanoparticle [ 27 ] ( Figure 2 C). In the fluorescence-based biosensor, the aptamer is adsorbed on the surface of a graphitic carbon nitride nanosheet, whose fluorescence is quenched.…”