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Magnetoresistive (MR) biosensors combine distinctive features such as small size, low cost, good sensitivity, and propensity to be arrayed to perform multiplexed analysis. Magnetic nanoparticles (MNPs) are the ideal target for this platform, especially if modified not only to overcome their intrinsic tendency to aggregate and lack of stability but also to realize an interacting surface suitable for biofunctionalization without strongly losing their magnetic response. Here, we describe an MR biosensor in which commercial MNP clusters were coated with gold nanoparticles (AuNPs) and used to detect human IgG in water using an MR biochip that comprises six sensing regions, each one containing five U-shaped spin valve sensors. The isolated AuNPs (satellites) were stuck onto an aggregate of individual iron oxide crystals (core) so that the resulting core@satellite magnetic particles (CSMPs) could be functionalized by the photochemical immobilization technique an easy procedure that leads to oriented antibodies immobilized upright onto gold. The morphological, optical, hydrodynamic, magnetic, and surface charge properties of CSMPs were compared with those exhibited by the commercial MNP clusters showing that the proposed coating procedure endows the MNP clusters with stability and ductility without being detrimental to magnetic properties. Eventually, the high-performance MR biosensor allowed us to detect human IgG in water with a detection limit of 13 pM (2 ng mL-1). Given its portability, the biosensor described in this paper lends itself to a point-of-care device; moreover, the features of the MR biochip also make it suitable for multiplexed analysis.

We consider extensions of General Relativity based on the non-local function $f(R, \Box^{-1} R)$, where $R$ is the Ricci curvature scalar and the non-locality is due to the term $\Box^{-1} R$. We focus on cosmological minisuperspaces and select viable models by the Noether Symmetry Approach. Then we find viable exact solutions pointing out the role of non-locality in cosmology., 13 pages

Conventional laboratory techniques exhibit impressive sensing performance and still constitute an irreplaceable tool in bioanalytics. Nevertheless, high costs, time consumption, and need for well-equipped laboratories and skilled personnel make highly desirable to explore novel strategies to carry out biochemical analyses. In this regard, biosensor-based methods represent a promising approach to keep affordability and rapidity, thus they can inherently pave the way to point of care tests and high-throughput analysis. Regrettably, most of them suffer from fabrication and biofunctionalization complexity, and poor sensitivities and reliability. Therefore, their adoption as a real alternative to the gold standards is still far from being achieved. However, the massive research on plasmonic nanostructures is revealing their potentialities in sensing field, since they own appealing performances resulting from the plasmon-related effects and can be easily adapted to a large variety of applications. In this review, a summary of plasmonic biosensors recently devised is reported. Though many nanostructures fit for shared applications, for clarity they are classified into two main categories: i) biosensors whose sensing parameters are plasmon-related observables (localized, coupled, lattice surface plasmon resonances) and ii) biosensors in which the nanostructure acts as amplifier for an external signal (surface-enhanced Raman and infrared spectroscopies and plasmon-enhanced fluorescence).