Hierarchical gold nanostructures based sensor for sensitive and fast detection of cancer biomarker

Importance of precision diagnostics in healthcare has been ignited by the idea that early detection of cancer would immensely benefit patients in terms of more effective and timely treatment modality. Clinical samples in the form of biopsy specimen/serum/urine/saliva contains an ocean of diagnostic information to generate conclusive information for more precise and evidence-based options to manage cancer. However, to achieve this, there is a need detect biomarkers, that can provide significantly increased diagnostic accuracy. Nanobiosensors have undoubtedly boomed to claim ultrasensitive detection of DNA cancer biomarkers in attomolar and femtomolar range. However, ultrasensitive and accurate detection of protein biomarker is rare. This work describes fabrication of a hierarchical gold nano-biosensor (HAu) for ultra-sensitive detection of cancer protein biomarkers in pg/mL range. Unique chemical modification during electrochemical synthesis has rendered highly uniformed and dense nanostructures of gold on a solid platform. Factors affecting homogeneity and sensitivity of the sensing platform have been optimized in detail. Voltammetric sensing based on antibody-antigen interaction on the given sensing platform has demonstrated a wide linear range of detection for EGFR varying from 10 pg/mL to 1 ng/mL concentration

Hierarchical gold nanostructures based sensor for sensitive and fast detection of cancer biomarker

135-140Importance of precision diagnostics in healthcare has been ignited by the idea that early detection of cancer would immensely benefit patients in terms of more effective and timely treatment modality. Clinical samples in the form of biopsy specimen/serum/urine/saliva contains an ocean of diagnostic information to generate conclusive information for more precise and evidence-based options to manage cancer. However, to achieve this, there is a need detect biomarkers, that can provide significantly increased diagnostic accuracy. Nanobiosensors have undoubtedly boomed to claim ultrasensitive detection of DNA cancer biomarkers in attomolar and femtomolar range. However, ultrasensitive and accurate detection of protein biomarker is rare. This work describes fabrication of a hierarchical gold nano-biosensor (HAu) for ultra-sensitive detection of cancer protein biomarkers in pg/mL range. Unique chemical modification during electrochemical synthesis has rendered highly uniformed and dense nanostructures of gold on a solid platform. Factors affecting homogeneity and sensitivity of the sensing platform have been optimized in detail. Voltammetric sensing based on antibody-antigen interaction on the given sensing platform has demonstrated a wide linear range of detection for EGFR varying from 10 pg/mL to 1 ng/mL concentration

Bio-inspired polydopamine layer as a versatile functionalisation protocol for silicon-based photonic biosensors

Photonic biosensors have made major advances in recent years, achieving very high sensitivity, and progressing towards point-of-care deployment. By using photonic resonances, sensors can be label-free, which is particularly attractive for a low-cost technological realisation. A key remaining issue is the biological interface and the efficient and reliable immobilisation of binder molecules such as antibodies; many protocols are currently in use that have led to widely varying sensor performance. Here, we study a very simple and robust surface functionalisation protocol for silicon photonics, which is based on polydopamine, and we demonstrate both its simplicity and its high performance. The use of polydopamine (PDA) is inspired by molluscs, especially mussels, that employ dopamine to adhere to virtually any surface, especially in an aqueous environment. We studied the versatility of the PDA protocol by showing compatibility with 5 different disease biomarkers (Immunoglobulin (IgG), C-reactive protein (CRP), Tumour Necrosis factor-α (TNF-α), Interleukin-6 (IL-6), Matrix metalloproteinase (MMP-9) and show that the protocol is resistant to hydrolysis during incubation; the loss of functionality due to hydrolysis is a major issue for many of the functionalisation protocols commonly used for silicon-based sensors. The study using guided mode resonance-based sensors highlights the wide dynamic range of the protocol (0.01 ng/mL to 1 μg/mL), using IgG, CRP and MMP-9 protein biomarkers as exemplars. In addition, we show that the surface chemistry allows performing measurements in 10% human serum with a sensitivity as low as 10 ng/mL for IgG. We suggest that adopting this protocol will make it easier for researchers to achieve biofunctionalisation and that the biosensor community will be able to achieve more consistent results

Rapid fabrication of homogeneously distributed hyper-branched gold nanostructured electrode based electrochemical immunosensor for detection of protein biomarkers

In recent years, need for rapid, reliable, and low-cost protein biomarker screening has tremendously boosted research into the development of electrochemical immunosensors. In this line, here we report on rapid fabrication and proof-of-concept demonstration of a hyper-branched gold nanostructure (ns@gold) based electrochemical immunosensor for detection of protein biomarker at pg/mL level. We have optimized a simple direct electrochemical process to rapidly generate uniformly distributed high surface area ns@gold within 30 min. These 3D ns@gold show ∼ 8-times enhancement in conductivity and also a rapid surface functionalization via self-assembled monolayers (SAM) of mercaptoundecanoic acid within 45 min. Protein estimation data showed around 94 % immobilization efficiency on the ns@gold surface in comparison to 28.4 % on plain gold surface. A fast SAM formation and quick antibody immobilization steered the assay timing within 4 h. As a proof-of-concept, we used an antibody-antigen interaction for the detection of epithelial growth factor receptor (EGFR) protein. Voltammetric data for the target EGFR receptor resulted a linear working range of 10 pg/mL to 100 ng/mL with a low limit-of-detection of 6.9 pg/mL. High selectivity in detecting target proteins from a pool of non-target proteins using breast cancer cell lines was also demonstrated along with good stability and reusability

Spray-n-Sense: Sprayable Nanofibers for On-Site Chemical Sensing

A versatile “Spray-n-Sense” sprayable nanofiber technology for on-site chemical detection is demonstrated. Driven by compressed gas, the “Spray-n-Sense” nanofibers, as the name suggests, can be directly sprayed onto any kind or shape of surfaces, while the embedded chemical reporter enables simple colorimetric/fluorometric detection. Herein, nanofibers are sprayed on several surfaces including cardboard, glass, plastic, and rubber. The sensing capabilities of the “Spray-n-Sense” nanofibers are established through the detection of three different analytes including two metal ions (Fe2+ and Fe3+ using 1,10-phenanthroline and curcumin as chromogenic reporters, respectively) and ammonia (using rhodamine-B as a fluorogenic reporter) in aqueous media. Additional to being highly portable, the “Spray-n-Sense” nanofibers show impressive sensor characteristics with a sub-ppm lower limit of detection (LLOD) for Fe2+ and a wide linear working range. Whereas, the LLOD of 6.2 and 32 ppm is achieved for Fe3+ ions and ammonia, respectively. A custom-designed smartphone application enables quantitative analysis for reliable on-site sensing. The selectivity and specificity are imparted by the embedded reporter, and thus allow analyte detection in complex real-life samples and simultaneous detection of multiple chemical species through co-doping. The “Spray-n-Sense” nanofibers also allow for the detection of target analytes in solid samples.</p