Nanoparticle-Based Bioaffinity Assays: From the Research Laboratory to the Market.

Advances in the development of new biorecognition elements, nanoparticle-based labels as well as instrumentation have inspired the design of new bioaffinity assays. This review critically discusses the potential of nanoparticles to replace current enzymatic or molecular labels in immunoassays and other bioaffinity assays. Successful implementations of nanoparticles in commercial assays and the need for rapid tests incorporating nanoparticles in different roles such as capture support, signal generation elements, and signal amplification systems are highlighted.

Atomic force microscopy and surface plasmon resonance for real-time single-cell monitoring of bacteriophage-mediated lysis of bacteria.

The growing incidence of multidrug-resistant bacterial strains presents a major challenge in modern medicine. Antibiotic resistance is often exhibited by Staphylococcus aureus, which causes severe infections in human and animal hosts and leads to significant economic losses. Antimicrobial agents with enzymatic activity (enzybiotics) and phage therapy represent promising and effective alternatives to classic antibiotics.

Laser-induced breakdown spectroscopy as a readout method for immunocytochemistry with upconversion nanoparticles.

Immunohistochemistry (IHC) and immunocytochemistry (ICC) are widely used to identify cancerous cells within tissues and cell cultures. Even though the optical microscopy evaluation is considered the gold standard, the limited range of useful labels and narrow multiplexing capabilities create an imminent need for alternative readout techniques. Laser-induced breakdown spectroscopy (LIBS) enables large-scale multi-elemental analysis of the surface of biological samples, e.

Detection of organic dyes by surface-enhanced Raman spectroscopy using plasmonic NiAg nanocavity films.

This work presents the NiAg nanocavity film for the detection of organic dyes by surface-enhanced Raman spectroscopy (SERS). Nanocavity films were prepared by colloidal lithography using 518-nm polystyrene spheres combined with the electrochemical deposition of Ni supporting layer and Ag nanoparticles homogeneous SERS-active layer. The theoretical study was modelled by finite-difference time-domain (FDTD) simulation of electromagnetic field enhancement near the nanostructured surface and experimentally proven by SERS measurement of selected organic dyes (rhodamine 6G, crystal violet, methylene blue, and malachite green oxalate) in micromolar concentration.

Competitive upconversion-linked immunoassay using peptide mimetics for the detection of the mycotoxin zearalenone.

Due to increasing food safety standards, the analysis of mycotoxins has become essential in the food industry. In this work, we have developed a competitive upconversion-linked immunosorbent assay (ULISA) for the analysis of zearalenone (ZEA), one of the most frequently encountered mycotoxins in food worldwide. Instead of a toxin-conjugate conventionally used in competitive immunoassays, we designed a ZEA mimicking peptide extended by a biotin-linker and confirmed its excellent suitability to mimic ZEA by nuclear magnetic resonance (NMR) and surface plasmon resonance (SPR) analysis.

Functionalizable Antifouling Coatings as Tunable Platforms for the Stress-Driven Manipulation of Living Cell Machinery.

Cells are continuously sensing their microenvironment and subsequently respond to different physicochemical cues by the activation or inhibition of different signaling pathways. To study a very complex cellular response, it is necessary to diminish background environmental influences and highlight the particular event. However, surface-driven nonspecific interactions of the abundant biomolecules from the environment influence the targeted cell response significantly.

Versatile Bioconjugation Strategies of PEG-Modified Upconversion Nanoparticles for Bioanalytical Applications.

Lanthanide-doped upconversion nanoparticles (UCNPs) display highly beneficial photophysical features for background-free bioimaging and bioanalysis; however, they are instable in high ionic strength buffers, have no functional groups, and are nonspecifically interacting. Here, we have prepared NIR-excitable UCNPs that are long-term colloidally stable in buffered media and possess functional groups. Heterobifunctional poly(ethylene glycol) (PEG) linkers bearing neridronate and alkyne or maleimide were attached to UCNPs via a ligand exchange.

Functional Plasma Polymerized Surfaces for Biosensing.

The capabilities of biosensors for fast, economic, and user-friendly analysis of complex samples has led to the exploitation of analytical devices for detection, quantification, and monitoring of specific chemical species for various applications. For a sufficiently high surface reactivity toward the adopted bioreceptors, a thin functional layer is required to enable coupling of the target biomolecules and to provide good stability in the presence of a sample matrix. In this work, the generation of water-stable oxygen-rich plasma polymerized (pp) films deposited by atmospheric-pressure jet plasma for reliable immobilization of biomolecules is presented.

Advances in Optical Single-Molecule Detection: En Route to Supersensitive Bioaffinity Assays.

The ability to detect low concentrations of analytes and in particular low-abundance biomarkers is of fundamental importance, e.g., for early-stage disease diagnosis.

Laser-induced breakdown spectroscopy as a novel readout method for nanoparticle-based immunoassays.

Laser-induced breakdown spectroscopy (LIBS) was examined as a novel method for readout of microtiter plate immunoassays involving nanoparticles (NP). The so-called Tag-LIBS technique is a sensitive method for the detection of specific biomarkers. It was applied to the determination of NP labels using nanosecond ablation sampling.

Maleic anhydride and acetylene plasma copolymer surfaces for SPR immunosensing.

We report on the successful application of carboxyl-rich plasma polymerized (PP) films as a matrix layer for bioreceptor immobilization in surface plasmon resonance (SPR) immunosensing. Composition and chemical properties of the carboxyl-rich PP films deposited from a mixture of maleic anhydride and acetylene were investigated. Changes in the films stored in air, water, and buffer were studied and the involved chemical changes were described.

Magnetic nanoparticles for smart electrochemical immunoassays: a review on recent developments.

This review (with 129 refs) summarizes the progress in electrochemical immunoassays combined with magnetic particles that was made in the past 5 years. The specifity of antibodies linked to electrochemical transduction (by amperometry, voltammetry, impedimetry or electrochemiluminescence) gains further attractive features by introducing magnetic nanoparticles (MNPs). This enables fairly easy preconcentration of analytes, minimizes matrix effects, and introduces an appropriate label.

Click-conjugated photon-upconversion nanoparticles in an immunoassay for honeybee pathogen Melissococcus plutonius.

European foulbrood (EFB) is an infectious disease affecting honeybee larvae caused by the bacterium Melissococcus plutonius. The enzyme-linked immunosorbent assay (ELISA) is the gold standard for antibody-based bacteria detection, however, its sensitivity is not high enough to reveal early-stage EFB infection. Photon-upconversion nanoparticles (UCNPs) are lanthanide-doped nanomaterials that emit light of shorter wavelength under near-infrared (NIR) excitation and thus avoid optical background interference.

Prussian Blue Nanoparticles as a Catalytic Label in a Sandwich Nanozyme-Linked Immunosorbent Assay.

Enzyme immunoassays are widely used for detection of analytes within various samples. However, enzymes as labels suffer several disadvantages such as high production cost and limited stability. Catalytic nanoparticles (nanozymes) can be used as an alternative label in immunoassays overcoming the inherent disadvantages of enzymes.

Enzymatic Precipitation Enhanced Surface Plasmon Resonance Immunosensor for the Detection of Salmonella in Powdered Milk.

Contamination of food by pathogenic bacteria has always been a serious threat for human health. The amount of food exports and imports has been increasing in recent years which requires precise food quality control with short analysis time and simplified sample treatment. Surface plasmon resonance (SPR) immunosensor enhanced by biocatalyzed precipitation was developed for the analysis of Salmonella in dairy products.