Current advances in the fabrication of smart nanomaterials and nanostructured surfaces find wide usage in the biomedical field. In this context, nanosensors based on localized surface plasmon resonance exhibit unprecedented optical features that can be exploited to reduce the costs, analytic times, and need for expensive lab equipment. Moreover, they are promising for the design of nanoplatforms with multiple functionalities (e.g., multiplexed detection) with large integration within microelectronics and microfluidics. In this review, we summarize the most recent design strategies, fabrication approaches, and bio-applications of plasmonic nanoparticles (NPs) arranged in colloids, nanoarrays, and nanocomposites. After a brief introduction on the physical principles behind plasmonic nanostructures both as inherent optical detection and as nanoantennas for external signal amplification, we classify the proposed examples in colloid-based devices when plasmonic NPs operate in solution, nanoarrays when they are assembled or fabricated on rigid substrates, and nanocomposites when they are assembled within flexible/polymeric substrates. We highlight the main biomedical applications of the proposed devices and offer a general overview of the main strengths and limitations of the currently available plasmonic nanodevices.

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Plasmonic Nanosensors: Design, Fabrication, and Applications in Biomedicine

Developing a simple and convenient approach for glucose sensing is crucially important in disease diagnosis and health monitoring. In this work, a glucose sensor based on plasmonic nanostructures was developed using gold–silver core–shell nanoparticles as the sensing platform. Based on the oxidative etching of the silver shell, the concentration of hydrogen peroxide and glucose could be determined quantitatively via the spectral change. This spectral change could also be observed with the naked eye or with a phone camera, realizing colorimetric sensing. To demonstrate this, glucose solutions at different concentrations were quantitatively detected in a wide concentration range of 0–1.0 mM using this colorimetric sensor. Importantly, shell thickness could significantly affect the sensitivity of our colorimetric sensor. This work provides a deeper understanding of the plasmonic sensing of glucose, which will help to realize its real applications. Based on this strategy, the non-invasive sensing of metabolites may be realized for disease diagnosis and health monitoring.

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Plasmonic Sensing of Glucose Based on Gold–Silver Core–Shell Nanoparticles

Optical wireless transmission has recently become a major cutting-edge alternative for on-chip/inter-chip communications with higher transmission speeds and improved power efficiency. Plasmonic nanoantennas, the building blocks of this new nanoscale communication paradigm, require precise design to have directional radiation and improved communication ranges. Particular interest has been paid to plasmonic Yagi–Uda, i.e., the optical analog of the conventional Radio Frequency (RF) Yagi–Uda design, which may allow directional radiation of plasmonic fields. However, in contrast to the RF model, an overall design strategy for the directional and optimized front-to-back ratio of the radiated far-field patterns is lacking. In this work, a guide for the optimized design of Yagi–Uda plasmonic nanoantennas is shown. In particular, five different design conditions are used to study the effects of sizes and spacing between the constituent parts (made of Au). Importantly, it is numerically demonstrated (using the scattered fields) that closely spaced nanoantenna elements are not appropriated for directional light-to-plasmon conversion/radiation. In contrast, if the elements of the nanoantenna are widely spaced, the structure behaves like a one-dimensional array of nanodipoles, producing a funnel-like radiation pattern (not suitable for on-chip wireless optical transmission). Therefore, based on the results here, it can be concluded that the constituent metallic rib lengths must be optimized to exhibit the resonance at the working wavelength, whilst their separations should follow the relation λeff/π, where λeff indicates the effective wavelength scaling for plasmonic nanostructures.

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Design of Plasmonic Yagi–Uda Nanoantennas for Chip-Scale Optical Wireless Communications

This paper is to discuss the potential of using CuZn in an electrical biosensor drug carrier for drug delivery systems. CuZn is the main semiconductor ingredient that has great promise as an electrochemical detector to trigger releases of active pharmaceutical ingredients (API). This CuZn biosensor is produced with a green metal of frameworks, which is an anion node in conductive polymers linked by bioactive ligands using metal–polymerisation technology. The studies of Cu, Zn, and their oxides are highlighted by their electrochemical performance as electrical biosensors to electrically trigger API. The three main problems, which are glucose oxidisation, binding affinity, and toxicity, are highlighted, and their solutions are given. Moreover, their biocompatibilities, therapeutic efficacies, and drug delivery efficiencies are discussed with details given. Our three previous investigations of CuZn found results similar to those of other authors’ in terms of multiphases, polymerisation, and structure. This affirms that our research is on the right track, especially that related to green synthesis using plant extract, CuZn as a nanochip electric biosensor, and bioactive ligands to bind API, which are limited to the innermost circle of the non-enzymatic glucose sensor category.

https://www.mdpi.com/1996-1944/15/21/7672/pdf?version=1667283649

CuZn Complex Used in Electrical Biosensors for Drug Delivery Systems

Regenerative medicine is the branch of medicine that effectively uses stem cell therapy and tissue engineering strategies to guide the healing or replacement of damaged tissues or organs. A crucial element is undoubtedly the biomaterial that guides biological events to restore tissue continuity. The polymers, natural or synthetic, find wide application thanks to their great adaptability. In fact, they can be used as principal components, coatings or vehicles to functionalize several biomaterials. There are many leading centers for the research and development of biomaterials in Italy. The aim of this review is to provide an overview of the current state of the art on polymer research for regenerative medicine purposes. The last five years of scientific production of the main Italian research centers has been screened to analyze the current advancement in tissue engineering in order to highlight inputs for the development of novel biomaterials and strategies.

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Biomaterials for Regenerative Medicine in Italy: Brief State of the Art of the Principal Research Centers

A hybrid plasmonic transducer made of a Poly‐(ethylene glycol) diacrylate (PEGDA) hydrogel and citrate gold nanoparticles detects the biotin‐streptavidin interaction at picomolar (× 10−12 m ) concentrations. The all‐solution fabrication strategy, herein proposed, is large‐scale, easily tunable, and low‐cost; nevertheless, this innovative device is highly reproducible and optically stable, and it can be used in dual‐optical mode. Indeed, both metal‐enhanced fluorescence and localized surface plasmon resonance signals can be exploited to quantify the biorecognition process in a 3D architecture. The large swelling capability of high molecular weight PEGDA is used to investigate the plasmon absorption variations resulting from the exposure to biological solutions containing high molecular weight molecules within the 3D network. The proposed transducer represents a low‐cost, flexible, and easy‐to‐use platform for sensing applications in biomedical or environmental diagnostics.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/admt.202101425

H3 (Hydrogel‐Based, High‐Sensitivity, Hybrid) Plasmonic Transducers for Biomolecular Interactions Monitoring

Interstitial fluid (ISF) extraction and analysis are challenges that can be tackled by Hollow MicroNeedles (HMNs) technology, overcoming most of the difficulties associated with in situ detection. Herein, a plasmonic transducer, composed of gold nanoparticles embedded in poly(ethylene glycol) diacrylate (PEGDA) hydrogels, is integrated in the inner cavity of HMNs to detect biomarkers from the ISF-based point-of-care. The wearable HMN-based patch is used for minimally invasive pierce of the skin. The large swelling capability of the plasmonic transducer allows the uptake of ISF by capillarity. Biotin, as a small model molecule, is efficiently collected in the inner cavity of HMN and its high specificity with the streptavidin is exploited as a validation of the plasmonic nanocomposite functionality embedded within. The recognition of biotin is achieved in dual-optical mode: the localized surface plasmon resonance (label-free) and the metal-enhanced fluorescence (label-based). Overall, the proposed HMN-based patch for target sensing in ISF can represent a novel point-of-use device for the detection of biomarkers as an alternative to conventional hospital or lab settings to help faster medical decision-making. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/admt.202300037

Hollow Microneedle‐based Plasmonic Sensor for on Patch Detection of Molecules in Dermal Interstitial Fluid

Herein, a novel completely green biosensor was designed exploiting both the biological and instrumental components made of eco-friendly materials for the detection of herbicides encapsulated into biodegradable nanoparticles for a sustainable agriculture. Similar nanocarriers, indeed, can deliver herbicides to the correct location, reducing the amount of active chemicals deposited in the plant, impacting the agricultural and food industries less. However, handling measurements of nanoherbicides is crucial to provide comprehensive information about their status in the agricultural fields to support farmers in decision-making. In detail, whole cells of the unicellular green photosynthetic alga Chlamydomonas reinhardtii UV180 mutant were immobilized by a green protocol on carbonized lignin screen-printed electrodes and integrated into a photo-electrochemical transductor for the detection of nanoformulated atrazine. Specifically, atrazine encapsulated into zein and chitosan doped poly-ε-caprolactone nanoparticles (atrazine-zein and atrazine-PCL-Ch) were analyzed following the current signals at a fixed applied potential of 0.8 V, in a range between 0.1 and 5 µM, indicating a linear relationship in the measured dose-response curves and a detection limit of 0.9 and 1.1 nM, respectively. Interference studies resulted in no interference from 10 ppb bisphenol A, 1 ppb paraoxon, 100 ppb arsenic, 20 ppb copper, 5 ppb cadmium, and 10 ppb lead at safety limits. Finally, no matrix effect was observed on the biosensor response from wastewater samples and satisfactory recovery values of 106 ± 8% and 93 ± 7% were obtained for atrazine-zein and atrazine-PCL-Ch, respectively. A working stability of 10 h was achieved.

https://www.mdpi.com/1422-0067/24/12/10088/pdf?version=1686658600

An All-Green Photo-Electrochemical Biosensor Using Microalgae Immobilized on Eco-Designed Lignin-Based Screen-Printed Electrodes to Detect Sustainable Nanoherbicides

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/admt.202270060

Bruno Miranda

Papers

Plasmonic Nanosensors: Design, Fabrication, and Applications in Biomedicine

H3 (Hydrogel‐Based, High‐Sensitivity, Hybrid) Plasmonic Transducers for Biomolecular Interactions Monitoring

Hollow Microneedle‐based Plasmonic Sensor for on Patch Detection of Molecules in Dermal Interstitial Fluid

An All-Green Photo-Electrochemical Biosensor Using Microalgae Immobilized on Eco-Designed Lignin-Based Screen-Printed Electrodes to Detect Sustainable Nanoherbicides

H 3 (Hydrogel‐Based, High‐Sensitivity, Hybrid) Plasmonic Transducers for Biomolecular Interactions Monitoring (Adv. Mater. Technol. 9/2022)