Label-free femtomolar cancer biomarker detection in human serum using graphene-coated surface plasmon resonance chips.

Sensitive and selective detection of cancer biomarkers is vital for the successful diagnosis of early stage cancer and follow-up treatment. Surface Plasmon Resonance (SPR) in combination with different amplification strategies is one of the analytical approaches allowing the screening of protein biomarkers in serum. Here we describe the development of a point-of-care sensor for the detection of folic acid protein (FAP) using graphene-based SPR chips. The exceptional properties of CVD graphene were exploited to construct a highly sensitive and selective SPR chip for folate biomarker sensing in serum. The specific recognition of FAP is based on the interaction between folic acid receptors integrated through π-stacking on the graphene coated SPR chip and the FAP analyte in serum. A simple post-adsorption of human serum:bovine serum albumin (HS:BSA) mixtures onto the folic acid modified sensor resulted in a highly anti-fouling interface, while keeping the sensing capabilities for folate biomarkers. This sensor allowed femtomolar (fM) detection of FAP, a detection limit well adapted and promising for quantitative clinical analysis.

Plasmonic photothermal destruction of uropathogenic E. coli with reduced graphene oxide and core/shell nanocomposites of gold nanorods/reduced graphene oxide.

The development of non-antibiotic based treatments against bacterial infections by Gram-negative uropathogenic E. coli is a complex task. New strategies to treat such infections are thus urgently needed. This report illustrates the development of pegylated reduced graphene oxide nanoparticles (rGO-PEG) and gold nanorods (Au NRs) coated with rGO-PEG (rGO-PEG-Au NRs) for the selective killing of uropathogenic E. coli UTI89. We took advantage of the excellent light absorption properties of rGO-PEG and Au NR particles in the near-infrared (NIR) region to photothermally kill Gram-negative pathogens up to 99% in 10 min by illumination of solutions containing the bacteria. The rGO-PEG-Au NRs demonstrated better photothermal efficiency towards E. coli than rGO-PEG. Targeted killing of E. coli UTI89 could be achieved with rGO-PEG-Au NRs functionalized with multimeric heptyl α-d-mannoside probes. This currently offers a unique biocompatible method for the ablation of pathogens with the opening of probably a new possibility for clinical treatments of patients with urinary infections.

Highly sensitive detection of DNA hybridization on commercialized graphene-coated surface plasmon resonance interfaces.

Strategies employed to interface biomolecules with nanomaterials have considerably advanced in recent years and found practical applications in many different research fields. The construction of nucleic acid modified interfaces together with the label-free detection of hybridization events has been one of the major research focuses in science and technology. In this paper, we demonstrate the high interest of graphene-on-metal surface plasmon resonance (SPR) interfaces for the detection of DNA hybridization events in the attomolar concentration range. The strategy consists on the noncovalent functionalization of graphene-coated SPR interfaces with gold nanostars carrying single-stranded DNA (ssDNA). Upon hybridization with its complementary DNA, desorption of the nanostructures takes place and thus enables the sensitive detection of the DNA hybridization event. The DNA sensor exhibits a detection limit of ≈500 aM for complementary DNA with a linear dynamic range up to 10(-8) M. This label-free DNA detection platform should spur off new interest toward the use of commercially available graphene-coated SPR interfaces.