Recent Advances in the Fabrication and Functionalization of Flexible Optical Biosensors: Toward Smart Life-Sciences Applications

Abstract

Over the last 30 years, optical biosensors based on nanostructured materials have obtained increasing interest since they allow the screening of a wide variety of biomolecules with high specificity, low limits of detection, and great sensitivity. Among them, flexible optical platforms have the advantage of adapting to non-planar surfaces, suitable for in vivo and real-time monitoring of diseases and assessment of food safety. In this review, we summarize the newest and most advanced platforms coupling optically active materials (noble metal nanoparticles) and flexible substrates giving rise to hybrid nanomaterials and/or nanocomposites, whose performances are comparable to the ones obtained with hard substrates (e.g., glass and semiconductors). We focus on localized surface plasmon resonance (LSPR)-based and surface-enhanced Raman spectroscopy (SERS)-based biosensors. We show that large-scale, cost-effective plasmonic platforms can be realized with the currently available techniques and we emphasize the open issues associated with this topic.

Plasmonic Nanosensors: Design, Fabrication, and Applications in Biomedicine

“…In recent years, great advances in nanotechnology have largely found applications in the field of biomedicine. In this context, the optical properties of metallic nanomaterials such as gold (Au) and silver (Ag) nanoparticles (NPs) have been exploited to produce nanodiagnostic and nano-therapeutic smart systems, which are simple, exhibit fast response times, and are relatively low-cost [1][2][3][4][5][6]. Physics, engineering, chemistry, and material science have been combined with biology, biotechnology, and medicine to produce biomedical devices that convert biological and/or biochemical signals into electrical ones through electrical, optical, electrochemical, or piezoelectric transducers [7][8][9][10][11].…”

“…The tailoring of the optical properties of plasmonic arrays can be engineered according to the desired applications by changing the size, shape, material, and distance of plasmonic NPs. Finally, polymeric nanocomposites can be obtained by three main mechanisms: deposition of colloidal NPs onto polymeric substrates, preparation of a pre-polymer solution embedding plasmonic NPs followed by curing (i.e., polymerization, curing, electrospinning), and in-situ reduction of plasmonic NPs on/within a polymeric matrix [3,41].…”

Design of Gelatin-Capped Plasmonic-Diatomite Nanoparticles with Enhanced Galunisertib Loading Capacity for Drug Delivery Applications

“…The mesoporous structure and surface tunability of DNPs allow the development of drug delivery systems for precision medicine [ 9 , 10 ]. Moreover, when DNPs are decorated by metal nanostructures, such as gold nanoparticles (AuNPs), silica acquires the intriguing optical properties of AuNPs that could be used for combining drug delivery with biosensing [ 11 , 12 , 13 ], bioimaging [ 14 ], phototherapy [ 15 ], and other applications [ 16 ]. Indeed, when the size of a noble metal (i.e., gold) is confined at the nanoscale, a phenomenon known as Localized Surface Plasmon Resonance (LSPR) [ 17 , 18 ], arises.…”

“…Indeed, when the size of a noble metal (i.e., gold) is confined at the nanoscale, a phenomenon known as Localized Surface Plasmon Resonance (LSPR) [ 17 , 18 ], arises. The coherent oscillation of electrons on the AuNP surface is responsible for the strong field enhancement in their surroundings and confers to hybrid systems composed of DNPs and AuNPs high sensitivity to local refractive index variations [ 12 , 19 , 20 ].…”

Plasmonic Hydrogel Nanocomposites with Combined Optical and Mechanical Properties for Biochemical Sensing

“…Plasmonic devices exploit the capability of noble-metal nanoparticles of absorbing light at a well-defined wavelength. The increasing request for wearable, flexible and easy-to-use diagnostic tools has brought to the development of plasmonic nanocomposites, whose peculiar performances arise from the combination of the optical properties of plasmonic nanoparticles and mechanical properties of the polymeric matrix in which they are embedded [2,3]. An optical platform based on spherical gold nanoparticles (AuNPs) embedded in high molecular weight poly-(ethylene glycol) diacrylate (PEGDA) hydrogel is proposed.…”