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The development of photothermal agents for antibacterial applications has become increasingly attractive. An exciting area for these materials is in the food industry where such materials can be applied to prevent microbial contamination, as an environment-friendly alternative to chemical disinfectants. However, for such applications, there is a need for low-cost photocatalytic materials with easy synthesis procedures and long-term stability. In this regard, copper sulfide (CuS) nanomaterials have gained vast attention for their large antimicrobial response, driven primarily by the photothermal effect resulting from their uniform absorption in the NIR range. However, an important factor for a successful application is the level of the light-to-heat conversion capability of the specific CuS nanomaterial, which highly impacts on the antimicrobial response. Here, different synthesis procedures were investigated to synthesize a variety of CuS particles with distinct sizes and shapes, to demonstrate the large variation in antimicrobial response. The antibacterial activity of the particles was demonstrated on the bacterium Escherichia coli (E. coli) by irradiation with a regular IR lamp, to simultaneously investigate light absorption under a relatively low irradiation power. The results reveal that the light absorption of the CuS particles vary greatly and thus also so does the antibacterial effect. In conclusion, the difference in antimicrobial effect can not only be ascribed to size and morphology, but it is also influenced by crystal size and phase composition.

In the context of biomaterials, small-molecules and drugs testing, intravital microscopy allows to quantify in-vivo the immune reaction, reducing the number of laboratory animals required to statistically validate the product. However, fluorescence microscopy is affected by limited tissue penetration due to light scattering and by optical aberrations, induced on focused beams, by the animal tissue surrounding the implant. In this framework, we developed a system of microlenses coupled to microscaffolds, both incorporated in a miniaturized imaging window. The chip is designed to act as an in-situ microscope objective with the aim to overcome the restrictions of in-vivo imaging (i.e. spherical aberrations) and to allow multiple biological observations in the same animal (by including fluorescent beacons). The device is fabricated by two-photon polymerizing a biocompatible photoresist called SZ2080. The microlenses are manufactured by the concentric polar scanning of the laser beam to realize their outer surface, followed by the UV bulk polymerization of their inner SZ2080. We preliminarily characterized the imaging capabilities of our implantable system on live cells cultured on flat substrates and 3D microscaffolds by coupling it to low magnification objectives. The microlenses optical quality is sufficient to induce non-linear excitation and collect two-photon excitation images with the same level of laser intensity and signal-to-noise ratio. Remarkably, they allow to efficiently excite the fluorescence of labelled human fibroblasts collecting high resolution magnified images. These results will open the way to the application of implanted micro-optics for the real-time and continuous in-vivo observation of complex biological processes.

Macrophages are immune cells which play a key role in the reaction to biomaterials. They exhibit a functional phenotype (or state) induced by the stimulus received and conditions of the microenvironment. This polarization process is governed by specific cytokines that are released by the macrophage itself, as well as produced by other cellular activation mechanisms. Cytokines act as phenotype markers within a heterogeneous range whose extremes are historically identified as pro-inflammatory or M1 and anti-inflammatory or M2. In such a context, this work aims to propose a predictive modeling approach for the simulation of the response to a pro-inflammatory stimulus in macrophages. This will allow us to subsequently simulate the immune reaction induced by the presence of biomaterials at the cellular level, with the final goal to build a digital twin of the inflammatory response in a foreign body reaction. To do that, existing Ordinary Differential Equation (ODE) and Agent Based (AB) models have been considered and validated with in-vitro experimental data. Preliminary results highlight a better agreement of the AB approach over the ODE models taken into account in this work. This specific scheme is making simplified assumptions on spatial resolution and diffusion of inflammation (both cytokine and macrophages). However, the good agreement that we have observed in this simplified model encourages the use of a more advanced and comprehensive hybrid simulation platform based on AB modeling which implements a more thorough description of the intracellular pathways and the microenvironment.

Tissue histopathology, based on hematoxylin and eosin (H&E) staining of thin tissue slices, is the gold standard for the evaluation of the immune reaction to the implant of a biomaterial. It is based on lengthy and costly procedures that do not allow longitudinal studies. The use of non-linear excitation microscopy in vivo, largely label-free, has the potential to overcome these limitations. With this purpose, we develop and validate an implantable microstructured device for the non-linear excitation microscopy assessment of the immune reaction to an implanted biomaterial label-free. The microstructured device, shaped as a matrix of regular 3D lattices, is obtained by two-photon laser polymerization. It is subsequently implanted in the chorioallantoic membrane (CAM) of embryonated chicken eggs for 7 days to act as an intrinsic 3D reference frame for cell counting and identification. The histological analysis based on H&E images of the tissue sections sampled around the implanted microstructures is compared to non-linear excitation and confocal images to build a cell atlas that correlates the histological observations to the label-free images. In this way, we can quantify the number of cells recruited in the tissue reconstituted in the microstructures and identify granulocytes on label-free images within and outside the microstructures. Collagen and microvessels are also identified by means of second-harmonic generation and autofluorescence imaging. The analysis indicates that the tissue reaction to implanted microstructures is like the one typical of CAM healing after injury, without a massive foreign body reaction. This opens the path to the use of similar microstructures coupled to a biomaterial, to image in vivo the regenerating interface between a tissue and a biomaterial with label-free non-linear excitation microscopy. This promises to be a transformative approach, alternative to conventional histopathology, for the bioengineering and the validation of

It is well known that copper oxide nanoparticles (CuO NPs) are heavily toxic on in vitro systems. In human alveolar epithelial cells, the mechanism of toxicity is mostly related to oxidative insults, coming from intracellularly dissolved copper ions, finally leading to apoptotic or autophagic cell death. Our hypothesis is based on possible early oxidative events coming from specific NP surface reactivity able to undermine the cell integrity and to drive cell to death, independently from Lysosomal-Enhanced Trojan Horse mechanism. Two types of CuO NPs, with different oxidative potential, were selected and tested on A549 cells for 1 h and 3 h at 10, 25, 50 and 100 µg/ml. Cells were then analyzed for viability and oxidative change of the proteome. Oxidative by-products were localized by immunocytochemistry and cell-NP interactions characterized by confocal and electron microscopy techniques. The results show that CuO NPs induced oxidative changes soon after 1 h exposure as revealed by the increase in protein carbonylation and reduced-protein-thiol oxidation. In parallel, cell viability significantly decreased, as shown by MTT assay. Such effects were higher for CuO NPs with more crystalline defects and with higher ROS production than for fully crystalline NPs. At these exposure times, although NPs efficiently interacted with cell surface and were taken up by small endocytic vesicles, no ion dissolution was visible inside the lysosomal compartment and no effects were produced by extracellularly dissolved copper ions. In conclusion, a specific NP surface-dependent oxidative cell injury was demonstrated. More detailed studies are required to understand which targets precociously react with CuO NPs, but these results introduce new paradigms for the toxicity of the metal-based NPs, beyond the Lysosomal-Enhanced Trojan horse-related mechanism, and open-up new opportunities to investigate the interactions and effects at the bio-interface for designing safer as well as more eff

The possibility to fabricate microstructures to be used in the medical field is a reality. Further steps in this direction consist in the fabrication of active microstructures for implants and/or for cellular treatments. Two major areas of interest will be briefly treated here. The first is the one of stimulus-responsive optical polymers, especially hydrogels, that can be shaped by means of laser 3D printing and ablation. These can be used for thermal stimulation, energy transduction and sensing. The composition of these polymeric blends is an essential parameter to tune their properties as actuators and/or sensing platforms and to determine the elasto-mechanical characteristics of the printed hydrogel. A second field of interest is the microfabrication of rigid microstructures that can stand the tissue-induced stresses in implants. The increasing demand of microdevices for nanomedicine and personalized medicine has fostered the quest for an efficient combination of composite and hybrid photo-responsive materials and digital micro/nano-manufacturing. Existing works have exploited multiphoton laser photo-polymerization to obtain fine 3D microstructures in hydrogels in an additive manufacturing approach or exploited laser ablation of preformed hydrogels to carve 3D cavities. The aim of this report is to provide a short overview of the basics of photo-polymerization induced by two-photon excitation and to discuss two case studies. In the first one, we discuss the most recent and prominent results in the field of multiphoton laser direct writing of biocompatible hydrogels that embed active nanomaterials not interfering with the writing process and endowing the biocompatible microstructures with physically or chemically activable features such as photo-thermal activity, chemical swelling and chemical sensing. In the second case, we outline the fabrication steps and the first tests of a novel chip which aims at enabling longitudinal studies of the reaction to the biomater

The Ras/cAMP/PKA pathway regulates responses to nutrients’ availability and stress in budding yeast. The cAMP levels are subjected to negative feedback, and we have previously simulated a dynamic model of this pathway suggesting the existence of stable oscillatory states depending on the symmetrical and opposed activity of the RasGEF (Cdc25) and RasGAPs (Ira proteins). Noisy oscillations related to the activity of this pathway were reported by looking at the nuclear localization of the transcription factor Msn2, and sustained oscillations of the nuclear accumulation of Msn2 under the condition of limiting glucose were observed. We were able to reproduce the periodic accumulation of Msn2-GFP protein in a yeast cell under the condition of limiting glucose, and we also detected oscillations of cAMP. We used a sensor based on a fusion protein between YFP-Epac2-CFP expressed in yeast cells. The FRET between CFP and YFP is controlled by the cAMP concentration. This sensor allows us to monitor changes in cAMP concentrations in a single yeast cell over a long time. Using this method, we were able to detect noisy oscillations of cAMP levels in single yeast cells under conditions of nutritional stress caused by limiting glucose availability.

Intravital microscopy windows for in vivo observation of tissue are desirable in many biomedical fields, from immunology to the assessment of the foreign body reaction to biomaterials. Moreover, they allow one to reduce the number of animals required to statistically validate biomaterials if compared with traditional histopathological analyses of animal biopsies [1,2].

We report new methods of 2 photon polymerization of microlenses with high numerical aperture, large diameter and good optical quality. We characterize the aberrations of these lenses that, coupled to raster scanning optical microscopes, allow two-photon excitation imaging of cells. In-vivo non-linear imaging will be also discussed, opening the possibility to use these micro-lenses in implants for the continuous inspection of biological dynamics in vivo.

Prussian blue (PB) is a coordination polymer based on the Fe2+...C[tbnd]N...Fe3+ sequence. It is an FDA-approved drug, intended for oral use at the acidic pH of the stomach and of most of the intestine track. However, based on FDA approval, a huge number of papers proposed the use of PB nanoparticles (PBnp) under “physiological conditions”, meaning pH buffered at 7.4 and high saline concentration. While most of these papers report that PBnp are stable at this pH, a small number of papers describes instead PBnp degradation at the same or similar pH values, i.e. in the 7–8 range. Here we give a definitively clear picture: PBnp are intrinsically unstable at pH ≥ 7, degrading with the fast disappearance of their 700 nm absorption band, due to the formation of OH- complexes from the labile Fe3+ centers. However, we show also that the presence of a polymeric coating (PVP) can protect PBnp at pH 7.4 for over 24 h. Moreover, we demonstrate that when “physiological conditions” include serum, a protein corona is rapidly formed on PBnp, efficiently avoiding degradation. We also show that the viability of PBnp-treated EA.hy926, NCI-H1299, and A549 cells is not affected in a wide range of conditions that either prevent or promote PBnp degradation.

Non-linear excitation microscopy offers several advantages for in-vivo imaging compared to conventional confocal techniques. However, tissue penetration can still be an issue due to scattering and spherical aberrations induced on focused beams by the tissue. The use of low numerical aperture objectives to pass through the outer layers of the skin, together with high dioptric power microlenses implanted in-vivo close to the observation volume, can be beneficial to the reduction of optical aberrations. Here, Fibroblast cell culture plano-convex microlenses to be used for non-linear imaging of biological tissue are developed and tested. The microlenses can be used as single lenses or multiplexed in an array. A thorough test of the lenses wavefront is reported together with the modulation transfer function and wavefront profile. Magnified fluorescence images can be retrieved through the microlenses coupled to commercial confocal and two-photon excitation scanning microscopes. The signal-to-noise ratio of the images is not substantially affected by the use of the microlenses and the magnification can be adjusted by changing the relative position of the microlens array to the microscope objective and the immersion medium. These results are opening the way to the application of implanted micro-optics for optical in-vivo inspection of biological processes.

We report new methods of 2 photon polymerization of microlenses with high numerical aperture, large diameter and good optical quality. We characterize the aberrations of these lenses that, coupled to raster scanning optical microscopes, allow two-photon excitation imaging of cells. In-vivo non-linear imaging will be also discussed, opening the possibility to use these micro-lenses in implants for the continuous inspection of biological dynamics in vivo.

The biocompatibility assessment of biomaterials or the dynamic response of implanted constructs entails inflammatory events primary reflected in cell behavior at the microcirculatory system. Current protocols are based on histopathology which are over 40 years old and require the sacrifice of a huge number of laboratory animal with an unsustainable ethical burden of animal research. Intravital microscopy techniques are actually used to study implantation outcomes in real time. However, no device providing a specific tracking geometry to reposition the field of view of the microscope, for repeated analyses, exists yet. The synthetic photoresist SZ2080 is characterized here, allowing the development and in vivo validation of a miniaturized imaging window, the Microatlas, that, fabricated via two-photon polymerization, is implanted in living chicken embryos and imaged by fluorescence microscopy 3 and 4 days after the implant. The characterization of their elastomechanical and fluorescence properties highlights planar raster spacing as the most important parameter in tuning the mechanical and spectroscopic features of the structures. The quantification of cell infiltration inside the Microatlas demonstrates its potential as novel scaffold for tissue regeneration and as beacon for 3D repositioning of the microscope field of view and correction of optical aberrations.

Surgical excision followed by histopathological examination is the gold standard for melanoma screening. However, the color-based inspection of hematoxylin-and-eosin-stained biopsies does not provide a space-resolved quantification of the melanin content in melanocytic lesions. We propose a non-destructive photo-thermal imaging method capable of characterizing the microscopic distribution and absolute concentration of melanin pigments in excised melanoma biopsies. By exploiting the photo-thermal effect primed by melanin absorption of visible laser light we obtain label-free super-resolution far-infrared thermal images of tissue sections where melanin is spatially mapped at sub-diffraction 40-µm resolution. Based on the finite-element simulation of the full 3D heat transfer model, we are able to convert temperature maps into quantitative images of the melanin molar concentration on B16 murine melanoma biopsies, with 4·10−4 M concentration sensitivity. Being readily applicable to human melanoma biopsies in combination with hematoxylin-and-eosin staining, the proposed approach could complement traditional histopathology in the characterization of pigmented lesions ex-vivo.

This work presents the development and experimental validation of an ultrasound piezoelectric sensor for thermoacoustic imaging that exploits printed circuit boards technology to define with high precision the sensor active area while minimizing manufacturing complexity and cost. A prototype single-channel sensor with 4x4 mm active area has been manufactured and experimentally validated in electrical and acoustic testbenches.

The emission of solar-induced chlorophyll fluorescence (F) is a pivotal process to infer vegetation health and functioning that can be monitored by remote sensing. However, most of the current remote sensing methods retrieve only F at top-of-canopy level, therefore making the link with physiological processes occurring at photosystem level not trivial. In this study, we develop a novel machine learning Fourier (phasor)-based algorithm to retrieve F both at canopy level and after considering the reabsorption (i.e. photosystem level), consistently with relevant biophysical variables, exploiting the canopy apparent reflectance spectra (Rapp). In particular, Rapp is divided in consecutive spectral windows, where the Discrete Fourier Transform (DFT) is computed. Then, the DFT results in each window are exploited to estimate the fluorescence spectra and biophysical parameters, together with their uncertainties, by means of a supervised machine learning algorithm coupled to a statistical-based retrieval pipeline. The algorithm has been trained through synthetic Rapp spectra, obtained from simulations based on a Radiative Transfer (RT) model. As a proof of concept, the theoretical approach is then applied to experimental data, acquired both from crops and forests, at close and high soil-sensor distance respectively, to evaluate the retrieval accuracy of biophysical and F parameters. In particular, for the first time Rapp is used to extract the temporal evolution of F at canopy and photosystem levels and its quantum efficiency together with different biophysical variables, during the growing season of two agricultural crops. Furthermore, tower-based solar-induced fluorescence measurements in a deciduous forest are exploited to evaluate the performance of our algorithm when the atmospheric reabsorption and scattering are not negligible. The reliability of the proposed method is evaluated through a comparison with F spectra extracted from the state of the art SpecFit retrieval

The main goal of this study is to develop methods for the simultaneous synthesis and loading of curcumin nanoparticles onto mesoporous silica by a sequential solvent evaporation approach. It is known that the presence of cosolvents and surfactants facilitates the homogenous formation of colloidal curcumin nanoparticles and enhances loading into mesoporous silica nanoparticles. The stability of the curcumin nanoparticles and their substantial loading are characterized as a function of the mesoporous silica nanostructures (MSN) surface properties, allowing to put into evidence how the dielectric nanoenvironment, largely determined by the water dynamics in the presence of cosolvents and of surfactants, plays a crucial role in the micelle mediated loading of curcumin nanoparticles into the mesoporous silica nanostructure. The interfacial hydrogen bonded corrugated network with its occupational electronic distribution shields the curcumin nanoparticles loaded onto the MSNs. Highly monodispersed nanostructures that are obtained that exhibit redox behavior, Fickian diffusion following linear compensation effect, and increased ionic activity triggered in an acidic pH ambiance. The augmented bioactivity of the human acute monocyte leukemia cancer cell line U937 elects the synthesized curcumin nanoparticles @ MSNs as a suitable nanostructure against acidic tumor microenvironment.

The current protocols for biocompatibility assessment of biomaterials, based on histopathology, require the sacrifice of a huge number of laboratory animals with an unsustainable ethical burden and remarkable cost. Intravital microscopy techniques can be used to study implantation outcomes in real time though with limited capabilities of quantification in longitudinal studies, mainly restricted by the light penetration and the spatial resolution in deep tissues. We present the outline and first tests of a novel chip which aims to enable longitudinal studies of the reaction to the biomaterial implant. The chip is composed of a regular reference microstructure fabricated via two-photon polymerization in the SZ2080 resist. The geometrical design and the planar raster spacing largely determine the mechanical and spectroscopic features of the microstructures. The development, in-vitro characterization and in vivo validation of the Microatlas is performed in living chicken embryos by fluorescence microscopy 3 and 4 days after the implant; the quantification of cell infiltration inside the Microatlas demonstrates its potential as novel scaffold for tissue regeneration.

H&E stained sections are the gold standard for disease diagnosis but, unfortunately, the staining process is time-consuming and expensive. In an effort to overcome these problems, here, we propose a virtual staining algorithm, able to predict an Hematoxylin/Eosin (H&E) image, usually exploited during clinical evaluations, starting from the autofluorescence signal of entire liver tissue sections acquired by a confocal microscope. The color and texture contents of the generated virtually stained images have been analyzed through the phasor-based approach to detect tumorous tissue and to segment relevant biological structures (accuracy>90% compared to the expert manual analysis).

We present a new AI-based method for the quantification of liver fibrosis in tissue sections stained with Picro Sirius Red which highlights collagen. The method segments and quantifies collagen, a marker of the fibrotic response, through a deep learning model trained on 20 whole-slide images. The results show a Dice score > 90% compared to manual annotations, demonstrating its potential aid during diagnosis. Furthermore, our approach can be extended to other staining protocols.

The possibility to shape stimulus-responsive optical polymers, especially hydrogels, by means of laser 3D printing and ablation is fostering a new concept of “smart” micro-devices that can be used for imaging, thermal stimulation, energy transducing and sensing. The composition of these polymeric blends is an essential parameter to tune their properties as actuators and/or sensing platforms and to determine the elasto-mechanical characteristics of the printed hydrogel. In light of the increasing demand for micro-devices for nanomedicine and personalized medicine, interest is growing in the combination of composite and hybrid photo-responsive materials and digital micro-/nano-manufacturing. Existing works have exploited multiphoton laser photo-polymerization to obtain fine 3D microstructures in hydrogels in an additive manufacturing approach or exploited laser ablation of preformed hydrogels to carve 3D cavities. Less often, the two approaches have been combined and active nanomaterials have been embedded in the microstructures. The aim of this review is to give a short overview of the most recent and prominent results in the field of multiphoton laser direct writing of biocompatible hydrogels that embed active nanomaterials not interfering with the writing process and endowing the biocompatible microstructures with physically or chemically activable features such as photothermal activity, chemical swelling and chemical sensing.

Collagen organization changes with the tissue pathological conditions, like cancer, and can be monitored through Second-Harmonic Generation imaging, a label-free method sensitive to the fibrils microstructure. As a consequence, collagen can be exploited as an early-tumor diagnosis marker. Coupling a phasorbased method with a non-supervised machine learning algorithm, our protocol is able to map pixel by pixel crucial features of the collagen fibrils and enlighten different collagen organizations. Basing on these maps, our protocol can automatically discriminate, on fixed tumor sections, tumor area from the surrounding tissue with an accuracy of ∼ 90%, opening the possibility to effectively assist histopathologists in cancer diagnosis.

The photothermal properties of nanoparticles (NPs), that is, their ability to convert absorbed light into heat, have been studied since the end of the last century, mainly on gold NPs. In the new millennium, these studies have developed into a burst of research dedicated to the photothermal ablation of tumors. However, beside this strictly medical theme, research has also flourished in the connected areas of photothermal antibacterial surface coatings, gels and polymers, of photothermal surfaces for cell stimulation, as well as in purely technological areas that do not involve medical biotechnology. These include the direct conversion of solar light into heat, a more efficient sun-powered generation of steam and the use of inkjet-printed patterns of photothermal NPs for anticounterfeit printing based on temperature reading, to cite but a few. After an analysis of the photothermal effect (PTE) and its mechanism, this minireview briefly considers the antitumor-therapy theme and takes an in-depth look at all the other technological and biomedical applications of the PTE, paying particular attention to photothermal materials whose NPs have joined those based on Au.

Two-photon and single photon laser writing are used here to fabricate 3D proteinaceous microstructures with photothermal functionality in the near-infrared spectral region and tunable elasticity. The photo-cross-linking is initiated in bovine serum albumin (BSA) by Rose Bengal and the photo-thermal effect arises from gold nanostars dispersed in the ink. Massive energy transfer of the plasmonic resonances of the gold nanostars to the photo-initiator is avoided by employing an anionic photo-initiator, allowing to obtain effective photo-crosslinking of BSA and to retrieve a substantial photo-thermal efficiency of the fabricated structures. On these microstructures, with a gold atom concentration as low as 1% w/w, a highly localized temperature increase can be quickly (≅1 s) reached and maintained under continuous wave laser irradiation at 800 nm. The photothermal efficiency under continuous wave laser irradiation depends on the thickness of the microstructure and can reach 12.2 +/- 0.4 °C/W. The Young modulus of the fabricated structures is estimated from the measurement of their bending under steady flow and falls in the range of most typical tissues, suggesting that they can be adopted as promising platform for future applications in regenerative nanomedicine.

We describe several bioengineered cell models developed by our group. We develop tools for cell culture allowing fluorescence diagnostics on the cellularised constructs cultured within, both in 3D and prolonged culture times extending to several weeks. These cell models proved able to recapitulate in vitro several slowly developing biological processes such as the regeneration of a cartilaginous tissue by cartilage cells, the formation of a bone metastasis by breast cancer cells, the instruction of adaptive immune cells as occurs in a lymphnode, and the neuroprotective effect on pathological neurons of mesenchymal stem cell secretome. We also scaled down these tools in the aim to better control stem cell function in our models, by applying two-photon laser polymerization to fabricate micro scaffolds for stem cell expansion. We were able to condition mesenchymal stem cells, neural precursor cells and embryonic stem cells towards maintenance of a greater stemness and multipotency/pluripotency, compared to conventional flat culture. This result opens an avenue towards a safer use of these cells for stem cells therapies. Finally, we describe our new revolutionary concept of implanting the cell model in a living organism to regenerate a vascularized network anastomosed to the host, allowing for studies involving interactions with the host immune system.

Bacterial contamination is a severe issue that affects medical devices, hospital tools and surfaces. When microorganisms adhere to a surface (e.g., medical devices or implants) they can develop into a biofilm, thereby becoming more resistant to conventional biocides and disinfectants. Nanoparticles can be used as an antibacterial agent in medical instruments or as a protective coating in implantable devices. In particular, attention is being drawn to photothermally active nanoparticles that are capable of converting absorbed light into heat. These nanoparticles can efficiently eradicate bacteria and biofilms upon light activation (predominantly near the infrared to near-infrared spectral region) due a rapid and pronounced local temperature increase. By using this approach new, protective, antibacterial surfaces and materials can be developed that can be remotely activated on demand. In this review, we summarize the state-of-the art regarding the application of various photothermally active nanoparticles and their corresponding nanocomposites for the light-triggered eradication of bacteria and biofilms.

This work presents the design and experimental validation of a photoacoustic setup that emulates the acoustic signal generated by a 20 MeV proton beam by ionoacoustic effect. This system serves as a practical tool to experimentally test ionoacoustic detectors in a simple yet representative setup prior to performing beam tests at accelerator facilities. To emulate the ionoacoustic effect the hereby presented Proton Sound Detector Testbench (ProSD-TB) uses a 70 W peak power pulsed laser and a specifically designed target absorber. The experimental validation of the ProSD-TB shows that it is capable to emulate a 20 MeV proton beam ionoacoustic signal in terms of signal amplitude (few Pa at the sensor surface) and frequency (2 MHz). The time domain signal generated by the ProSD-TB is acquired by means of a 64-ch Proton Sound Detector composed by a multichannel acoustic sensor, a dedicated analog front-end and signal processing. The ProSD-TB is validated against a 20 MeV ionoacoustic signal both in time domain and by comparing the 20 MeV dose deposition profile to an acoustic image generated by the Proton Sound Detector.

This article presents the complete photon-to-bit cross-domain model of a photoacoustic melanoma detector (paMELA), consisting of a pulsed laser, a multichannel acoustic sensor, an analog front-end and a DSP stage for the implementation of an acoustic imaging algorithm. The photoacoustic effect can be exploited to obtain complementary information on a suspected melanoma with respect to classical dermatoscopic techniques. By modelling the physical phenomena (generation and propagation of the acoustic signal), electromechanical process (pressure-voltage transduction by the acoustic sensor), the analog and digital signal processing, it is possible to evaluate the impact of each stage on the quality of the final image. Finally, the simulation results of paMELA allow to evaluate the performance of the detector in terms of localization precision and signalto-noise ratio, using both a single point-like source and a complete biological tissue phantom with different sources sizes and features, obtaining 18 dB of SNR and 10 mu m of precision in is acquisition.

Heating has been recently used as an alternative application to electrical stimulation to modulate excitability and to induce neuritogenesis and the expression of neuronal markers, but a long-term functional differentiation has not been described so far. Here we present the results obtained by a new approach for scalable thermal stimulation on the behavior of a model of dorsal root ganglion neurons, the F-11 cell line. Initially, we performed experiments of bulk stimulation in incubator for different time intervals and temperatures, and significant differences in neurite elongation and in electrophysiological properties were observed in cultures exposed at 41,5°C for 30 minutes. Thus, we exposed the cultures to the same temperature increase by irradiating, with a near infrared laser, a disc of Prussian Blue nanoparticles and poly-vinyl alcohol, that we stuck on the outer surface of the petri dish. In irradiated cells neurites were significantly longer and the electrophysiological properties (action potential firing frequency and spontaneous activity) were significantly increased compared to the control. These results suggest that a targeted thermal stimulation could be a promising technique to induce differentiation and support the future application of this method as a strategy to modify neuronal behavior in vivo.

Nanoparticles with absorption in Near-Infrared (NIR) region and subsequent efficient release of heat, are receiving great attention due to wide opportunities of applications in different fields including biotechnology and nanomedicine. However, the colloidal solutions of such nanoparticles may have limitations in effective application connected with long-term stability of nanoparticle solutions and possible re-usability. Therefore, this minireview focuses on the state-of-the art of research and application of photothermally active nanoparticles to engineer remotely activated materials with controllable photothermal properties: printed surfaces and polymeric nanocomposite materials. We highlight in this minireview different types of photothermally active nanoparticles (e.g. non-spherical gold nanoparticles, copper sulfide nanoparticles) that already have been applied for fabrication of printed patterns and polymeric nanocomposites, the properties of the resulting materials and further application opportunities.