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Measurement of the surface free energy (SFE) of a material allows the prediction of its adhesion properties.

Temporal and spectral behaviors of plasmons determine their ability to enhance the characteristics of metamaterials tailored to a wide range of applications, including electric-field enhancement, hot-electron injection, sensing, as well as polarization and angular momentum manipulation. We report a dark-field (DF) polarimetry experiment on single particles with incident circularly polarized light in which gold nanoparticles scatter with opposite handedness at visible wavelengths. Remarkably, for silvered nanoporous silica microparticles, the handedness conversion occurs at longer visible wavelengths, only after adsorption of molecules on the silver. Finite element analysis (FEA) allows matching the circular polarization (CP) conversion to dominant quadrupolar contributions, determined by the specimen size and complex susceptibility. We hypothesize that the damping accompanying the adsorption of molecules on the nanostructured silver facilitates the CP conversion. These results offer new perspectives in molecule sensing and materials tunability for light polarization conversion and control of light spin angular momentum at submicroscopic scale.

Background Modelling of needle insertion in soft tissue has developed significant interest in recent years due to its application in robot-assisted minimally invasive surgeries such as biopsies and brachytherapy. However, this type of surgery requires real-time feedback and processing which complex computational models may not be able to provide. Methods In contrast to the existing mechanics-based kinetic models, a simple multilayer tissue model using a Coupled Eulerian Lagrangian based Finite Element method has been developed using the dynamic principle. The model simulates the needle motion for flexible hollow bevel-angled needle (15° and 30°, 22 G) insertion into porcine liver tissue, which includes material parameters obtained from unconfined compression testing of porcine liver tissue. To validate simulation results, needle insertion force and cutting forces within porcine liver tissue were compared with corresponding experimental results obtained from a custom-built needle insertion system. Results For the 15° and 30° bevel-angle needles, the percentage error for cutting force (mean) of each needle compared to computational model, were 18.7% and 11.9% respectively. Varying the needle bevel angle from 30° to 15° results in an increase of the cutting force, but insertion force does not vary among the tested bevel angles. Conclusion The validation of this computationally efficient multilayer Finite Element model can help engineers to better understand the biomechanical behaviour of medical needle inside soft biological tissue. Ultimately, this multilayer approach can help advance state-of-art clinical applications such as robot-assisted surgery that requires real-time feedback and processing. Statement of Significance The significance of the work is in confirming the effectiveness of multilayer material based finite element (FE) method to model biopsy needle insertion into soft biological porcine liver tissue. A multilayer Coupled Eulerian Lagrangian (CEL) based FE modelling technique allowed testing of heterogeneous, non-linear viscoelastic porcine liver tissue in a system, so direct comparison of needle tissue interaction forces on the intrinsic material (tissue) behaviour could be made. To the best of the authors’ knowledge, the present research investigates for the first time modelling of a three dimensional (3D) hollow needle insertion using a multilayer stiffness model of biological tissue using FE based CEL method and presents a comparison of simulation results with experimental data.

The current study reports the synthesis, characterization and tape casting of strontium substituted into the calcium sublattice of hydroxyapatite in range of (0–100 mol%). The XRD powder data reveals that a primary HAp phase as well as secondary Ca 3 (PO 4 ) 2 (β-TCP) phase coexist. Our analysis shows that Sr+2 preferentially occupies the HAp lattice sites rather than β-TCP. Developed free-standing tapes of HAp offer unique possibility of custom designed solutions for biomedical applications by controlling shape size and tuned electrical properties. We report piezoelectricity in Sr doped hydroxyapatites thick films, the piezoelectric coefficient is an order of magnitude higher than what has been previously obtained in PLD deposited hydroxyapatite films [15]. The piezoelectricity shows slight improvement with the Sr doping. Despite low piezoelectric coefficient, the generated voltage is of the order of mV which is high enough to have physiological relevance since the resting potential of the cells lie between 60–90 mV. Further improvements in the material design and poling could pave way to understand the role of electricity in bone growth and to use piezoelectric energy harvesting to tune spinal and neuro stimulators.

Here, we report the growth of bioelectret crystal films of L-leucine on conductive substrates and detail the first quantitative measurements of the direct piezoelectric effect in this proteinogenic amino acid. Through extensive electromechanical characterisation, we demonstrate that L-leucine is a promising candidate material for use in non-toxic, biocompatible and biodegradable energy harvesting and sensing devices. The data presented here is among, if not the, largest set of quasi-static, longitudinal piezoelectric measurements on crystalline films of a proteinogenic amino acid to date. We substantiate these measurements using a combination of density functional theory calculations and optical microscopy. Our data provides a further example of the enormous unexploited potential of amino acids and similar biological materials in flexible energy harvesting applications. Their combination of sizeable piezoelectric strain constants and extremely low elastic and dielectric constants makes them ideal as biocompatible replacements for toxic, expensive inorganic piezoelectric materials.

We report fabrication and piezo- and pyroelectric characterizations of spark plasma sintered (SPS) lead-free K 0.5 Na 0.5 NbO 3 (KNN) ceramics. SPS sintering produced dense KNN (99% of the theoretical density) at sintering temperature as low as 900°C. A significant improvement in the dielectric, piezoelectric and pyroelectric properties is observed after annealing the sample at 925°C. The measured piezoelectric coefficient d 33 and pyroelectric coefficient of poled KNN ceramic are 94 pC/N and 22.84 μCm−2K−1, respectively. These values are high enough to focus on the further enhancement of the material properties through adequate control of the phase structure of the material for lead-free energy harvesting applications.

peer-reviewed A disruptive method of fabricating free-standing tapes of La-doped (BaCaSrPb)TiO3 thermistors is demonstrated. The greatest advantage is that the free-standing tapes do not require high temperature co-firing of electrodes or reduced environment cofiring soft oxidation cycle to obtain thermal sensitivity. The approach thus solves the longstanding problem with the ceramic thermistor technology that eluded its compatibility with surface mount technology (SMT) and miniaturization. Stencil printing is employed that can fabricate up to 500 µm thick tapes in a single step, saving huge cost and processing steps for application requiring thicker films. The pastes suitable for freestanding tapes are reported. The method provides a novel route to integrate PTC elements into the chips of passive components and would lead to a massive reduction in cold resistivity when developed in multilayer laminated stacks.

Broadband mid-infrared (B-MIR) thermography using fibre optic waveguides can be critical in real-time imaging in harsh environments such as additive manufacturing, personalised medical diagnosis and therapy. We investigate the polarisation effect on thermal measurements through poly-crystalline fibre bundle employing a simple broadband cross-polarisation configuration experimental set-up. Silver halide poly-crystalline fibres AgCl1−xBrx (0 ≤ x≤1) (AgClBr-PolyC) have very wide transmission bandwidth spanning over the spectral range from 1 µm up to 31 µm FWHM. Moreover, they are non-toxic, non-hygroscopic, with relatively good flexibility, which make them very adequate for spectroscopic and thermal measurements in medical and clinical fields. In this study, we used a fibre bundle composed of seven single AgClBr-PolyC fibres, each with a core diameter of about 300 µm, inserted between two broadband MIR polarisers.A silicon carbide filament source was placed at the entrance of the fibre bundle, while a FLIR thermal camera with a close-up lens was employed to measure the spatial temperature distribution over the fibre-bundle end. Indeed, polarisation dependence of temperature measurements has been clearly observed in which the orientation of temperature extrema (minima and maxima)vary from one fibre to another within the bundle. Moreover, these observations have enabled the classification of AgClBr-PolyC fibres following their polarisation sensitivities by which some fibres are relatively highly sensitive to polarisation with polarisation temperature difference (PTD) that can reach 22.1 ± 2.8 °C, whereas some others show very low PTD values down to 3.1 ± 2.8 °C. Many applications can readily be found based on the advantages of both extreme cases. © 2020, The Author(s). SM, AM, CS, JB and SAMT acknowledge European Commission Erasmus International Credit Mobility 2015–2020 between Ural Federal University named after the frst President of Russia B.N. Yeltsin, Yekaterinburg, Russia, and University of Limerick, Ireland, as well as Erasmus Bilateral Exchange between Wroclaw University of Science and Technology, Poland, and University of Limerick, Ireland, 2010–2020 for funding the work on imaging, characterisation and application development using MIR bundle fbres in medicine and manufacturing. JB acknowledges European Commission Erasmus+KA107 Inter-institutional Student and Staf Mobility Programme 2018–2020 between Wroclaw University of Science and Technology, Poland, and Ural Federal University, Yekaterinburg, Russia. SM and AM acknowledges Science Foundation Ireland (SFI) Centre for Medical Devices co-funded under the European Regional Development Fund (Grant Number 13/RC/2073) for characterising bundle fbre. EK, AK and LZ acknowledge Grant No. 18-73-10063 from the Russian Science Foundation for funding the fabrication of fbre bundles.

In this study, we propose a way for miniaturization of mid-infrared (MIR) fibre bundles while maintaining low crosstalk and transmission losses. Such miniaturization of fibres is important when applying MIR in thin polycrystalline AgCl0.25Br0.75 fibres with a diameter of 110 µm, made using custom-designed extrusion components. These fibres were then mechanically assembled in an optical bundle of seven hexagonally arranged fibres. Transmission of MIR from a heat source through this bundle was compared with similar bundle of seven fibres with a diameter of 300 µm. It was found that both bundles are transparent to MIR in the spectral range of 2–20 µm corresponding to temperature range from –130 to + 1150 °C. They also have low crosstalks (

In this paper, we use a Multiphysics approach in COMSOL™ Platform to develop and validate a finite element model that simulates thermal images obtained in active thermography mode. This approach allows variation in material properties, the selection of active thermography methods such as Flash, Pulse Phase & Lock-in techniques, source wavelength, depth and dimensions of defect. We then take experimental thermography images of a defect embedded into a PLA block to compare with simulated images generated by the Multiphysics model. Our work shows the feasibility of real-time three-dimensional (3D) active infrared thermography (IRT) of buried defects. Such imaging can be hugely beneficial not only in quality control and process optimisation in additive manufacturing but also determination of shape and outline of tumours and plaques in medical applications.

The development of electrochemiluminescent (ECL) luminophores with tuneable emission profiles is a key requirement in the development of multi-analyte ECL sensing platforms. This study presents the first reported use of cadmium selenide sulfide (CdSeS) quantum dots (QDs) as ECL emitters in which both the ECL emission profile and cathodic potential can be tailored by alteration of the Se/S ratio. CdSeS QDs were synthesised using an aqueous synthetic route thereby avoiding the use of organic reagents, high temperatures and inert gasses. The suitability of the CdSeS QDs to ECL sensing applications is demonstrated via the quantitative determination of TIMP-1 protein at clinically relevant concentrations. The developed cathodic ECL immunosensor exhibited a detectable linear range of 6-60 ng/mL and a limit of detection (LOD) of 1.54 ng/mL. TIMP-1 protein plays a crucial role in pregnancy, wound healing, and cancer prognosis.

We report a significant spectral drift (up to 110 nm) between optical scattering and extinction in magnetite-gold (Fe3O4-Au) core–shell nanostructures. The drift was observed experimentally using single-particle broadband dark-field scattering microspectroscopy and solution extinction experiments. Infrared thermography demonstrates an enhanced photothermal activity of these nanoparticles at extinction wavelengths that are far drifted from the wavelengths that produce the best results for imaging via scattering. For example, a relatively smooth gold shell leads to 19% more photothermal activity at 532 nm compared to 690 nm whereas a rough-texture, popcorn type morphology gold shell with three times higher drift, is 170% more efficient at 532 nm. We suggest that the enhanced photothermal response results directly from a reduced competition between absorption and scattering as a consequence of the spectral drift. This spectral drift can be advantageous in multimodal theranostics where therapy and imaging are performed independently at different wavelengths.

Calcium carbonate and carbonate-hydroxyapatite are known to form inorganic components of crystals and calcareous concretions found in many non-skeletal tissues and structures including the pineal gland. We used advanced surface analyses techniques such as polarization microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), microfocus X-ray diffraction (XRD), transmission electron microscopy with selected area electron diffraction (TEM-SAED) to investigate samples extracted from rat pineal gland after irradiation with visible light for 12 h. Single-crystal X-ray diffraction showed that the concretions were largely amorphous with the presence of some nanocrystalline phases. High resolution TEM-SAED revealed the presence of iron oxide in the form of hematite. Spectroscopy data especially Raman spectroscopy revealed a mixed nature of these concretions, which corresponded reasonably with XPS, TEM and XRD. Overall the study confirms the presence of a mixed phase of calcium carbonates including calcite, aragonite and vaterite. We note that aragonite is not a common occurrence in vertebrates and recommend further investigation to rule out any link to pathology.

Cocrystallization of two or more molecular compounds can dramatically change the physicochemical properties of a functional molecule without the need for chemical modification. For example, coformers can enhance the mechanical stability, processability, and solubility of pharmaceutical compounds to enable better medicines. Here, we demonstrate that amino acid cocrystals can enhance functional electromechanical properties in simple, sustainable materials as exemplified by glycine and sulfamic acid. These coformers crystallize independently in centrosymmetric space groups when they are grown as single-component crystals but form a noncentrosymmetric, electromechanically active ionic cocrystal when they are crystallized together. The piezoelectricity of the cocrystal is characterized using techniques tailored to overcome the challenges associated with measuring the electromechanical properties of soft (organic) crystals. The piezoelectric tensor of the cocrystal is mapped using density functional theory (DFT) computer models, and the predicted single-crystal longitudinal response of 2 pC/N is verified using second-harmonic generation (SHG) and piezoresponse force microscopy (PFM). The experimental measurements are facilitated by polycrystalline film growth that allows for macroscopic and nanoscale quantification of the longitudinal out-of-plane response, which is in the range exploited in piezoelectric technologies made from quartz, aluminum nitride, and zinc oxide. The large-area polycrystalline film retains a damped response of ≥0.2 pC/N, indicating the potential for application of such inexpensive and eco-friendly amino acid–based cocrystal coatings in, for example, autonomous ambient-powered devices in edge computing., Glycine and sulfamic acid form an ionic cocrystal that demonstrates a measurable longitudinal piezoelectric response in single-crystal and polycrystalline form. The crystals are characterized using piezoresponse force microscopy and second harmonic generation, and the material properties are rationalized and quantified using density functional theory calculations.

Recent advances in nanoscale lasers, amplifiers, and nonlinear optical converters have demonstrated the unprecedented potential of metal–insulator–semiconductor (MIS) structures as a versatile platform to realize integrated photonics at the nanoscale. While the electric field enhancement and confinement have been discussed intensively in MIS based plasmonic structures, little is known about the carrier redistribution across the heterojunction and photocurrent transport through the oxide. Herein, we investigate the photo-generated charge transport through a single CdSe microbelt- Al 2 O 3 -Ag heterojunction with oxide thickness varying from 3 nm to 5 nm. Combining photocurrent measurements with finite element simulations on electron (hole) redistribution across the heterojunction, we are able to explain the loss compensation observed in hybrid plasmonic waveguides at substantially reduced pump intensity based on MIS geometry compared to its photonic counterpart. We also demonstrate that the MIS configuration offers a low-dark-current photodetection scheme, which can be further exploited for photodetection applications.

The indiscriminate and sporadic use of antibiotics has contributed to the emergence of drug resistance phenomenon in bacteria including but not limited to Staphylococcus aureus. These drug-resistant bacteria have been threatening safety in hospitals and adversely affecting human health. Here we report a strategy to design photo-stimulated theranostic nanoprobes against methicillin-resistant Staphylococcus aureus (MRSA) “superbug” USA300. The nanocapsule probe is based on gold nanorods (GNRs) coated with pegylated thiol, mPEG-SH, which has been further modified by adding successively a natural antibacterial compound such as curcumin, and a cell targeting deoxyribonucleic acid (DNA) aptamer. We have used this novel gold nanocapsules for near-infrared (NIR) photophysical stimulation against pathogenic bacteria. We have found that the novel nanocapsule blocks biofilm formation and kills bacteria by photothermal action that causes disruption of the bacterial cell wall and membrane. In this approach, multiple drug-resistant Staphylococcus aureus has been captured by these nanocapsules through DNA aptamer targeting. All of the trapped bacteria could be killed in 30 minutes during the NIR stimulation due to the combination of photothermal effect, the generation of reactive oxygen species (ROS) and a loss of transmembrane potential (Δψ). Importantly we did not notice any resistance developed against the photothermal treatment. This is remarkable from an anti-biofilm activity point of view. Importantly, these multifunctional nanocapsules have also shown a surface enhanced Raman spectroscopy (SERS) effect, which could be used to evaluate the success of the inactivation effect during treatment. These results indicate that nanocapsule-based photo treatment can be an alternative antibacterial strategy without contributing to antibiotic resistance, and thus can be used for both environmental and therapeutic applications.

Fe3O4&ndash, Au core&ndash, shell magnetic-plasmonic nanoparticles are expected to combine both magnetic and light responsivity into a single nanosystem, facilitating combined optical and magnetic-based nanotheranostic (therapeutic and diagnostic) applications, for example, photothermal therapy in conjunction with magnetic resonance imaging (MRI) imaging. To date, the effects of a plasmonic gold shell on an iron oxide nanoparticle core in magnetic-based applications remains largely unexplored. For this study, we quantified the efficacy of magnetic iron oxide cores with various gold shell thicknesses in a number of popular magnetic-based nanotheranostic applications, these included magnetic sorting and targeting (quantifying magnetic manipulability and magnetophoresis), MRI contrasting (quantifying benchtop nuclear magnetic resonance (NMR)-based T1 and T2 relaxivity), and magnetic hyperthermia therapy (quantifying alternating magnetic-field heating). We observed a general decrease in magnetic response and efficacy with an increase of the gold shell thickness, and herein we discuss possible reasons for this reduction. The magnetophoresis speed of iron oxide nanoparticles coated with the thickest gold shell tested here (ca. 42 nm) was only ca. 1% of the non-coated bare magnetic nanoparticle, demonstrating reduced magnetic manipulability. The T1 relaxivity, r1, of the thick gold-shelled magnetic particle was ca. 22% of the purely magnetic counterpart, whereas the T2 relaxivity, r2, was 42%, indicating a reduced MRI contrasting. Lastly, the magnetic hyperthermia heating efficiency (intrinsic loss power parameter) was reduced to ca. 14% for the thickest gold shell. For all applications, the efficiency decayed exponentially with increased gold shell thickness, therefore, if the primary application of the nanostructure is magnetic-based, this work suggests that it is preferable to use a thinner gold shell or higher levels of stimuli to compensate for losses associated with the addition of the gold shell. Moreover, as thinner gold shells have better magnetic properties, have previously demonstrated superior optical properties, and are more economical than thick gold shells, it can be said that &ldquo, less is more&rdquo

We report a significant spectral drift (up to 110 nm) between optical scattering and extinction in magnetite-gold (Fe

We report a significant spectral drift (up to 110 nm) between optical scattering and extinction in magnetite- gold (Fe3O4-Au) core–shell nanostructures. The drift was observed experimentally using single-particle broadband dark-field scattering microspectroscopy and solution extinction experiments. Infrared thermography demonstrates an enhanced photothermal activity of these nanoparticles at extinction wavelengths that are far drifted from the wavelengths that produce the best results for imaging via scattering. For example, a relatively smooth gold shell leads to 19% more photothermal activity at 532 nm compared to 690 nm whereas a rough-texture, popcorn type morphology gold shell with three times higher drift, is 170% more efficient at 532 nm. We suggest that the enhanced photothermal response results directly from a reduced competition between absorption and scattering as a consequence of the spectral drift. This spectral drift can be advantageous in multimodal theranostics where therapy and imaging are performed independently at different wavelengths

peer-reviewed Advances in Label Free Tissue Imaging with Laser Scanning Microscopy Techniques

In this paper we investigated spectral transmission of irradiated IR fibres derived from single crystals of AgCl-AgBr and AgBr-TlI solid solutions. The fibres were exposed to β- and γ-radiation. The highest absorbed dose was 500 kGy. It was found that even modest radiation doses cause a reduction in transmission in AgCl-AgBr fibres within the entire working wavelength range, while for AgBr-TlI fibres the irradiation causes an increase in transmission when compared to corresponding values of non-irradiated fibres at wavelengths of 4–6 µm. We proposed a mechanism of this radiation-induced translucence and we expect that this phenomenon may be used for improvement of optical fibres. Additionally, we investigated how the transmission of AgCl-AgBr irradiated fibres depends on time after irradiation. Summarizing, both kinds of the fibres are suitable for applications in high radiation environments, for example, as a probe in on-line remote IR spectroscopy.

Nanometrology refers to measurement techniques that assess materials properties at the nanoscale. Laboratory-based characterisation of nanomaterials has been the key enabler in the growth of nanotechnology and nano-enabled products. Due to the small size involved, dimensional measurements has dominated such characterisation underpinned by a tremendous development in stand-alone electron/ion microscopes and scanning probe microscopes.However, the scope of nanometrology extends far beyond off-site, laboratory-based measurements of dimensions only, and is expected to have a tremendous impact on design of nano-enabled materials and devices.In this article, we discuss some of the available techniques for laboratory-based characterisation of mechanical and interfacial properties for nanometrology. We also provide a deep insight into the emerging techniques in measuring these properties, keeping in view the need in advanced manufacturing and nanobio-interactions to develop multifunctional instrumentation, traceable and standardized methods, and modelling tools for unambiguous data interpretation.We also discuss the evaluation of nanomechanical properties and surface/interface response of materials, within the purview of manufacturing processes and standardization.Finally, we discuss scientific and technological challenges that are required to move towards real-time nano-characterisation for rapid, reliable, repeatable and predictive metrology to underpin upscaling nanomaterials and nano-enabled products from the research field to industry and market. Keywords: Nanometrology, Nanoindentation, AFM, Bio, Microscopy, Nanoscopy

Bioinspired assemblies bear massive potential for energy generation and storage. Yet, biological molecules have severe limitations for charge transfer. Here, we report l-tryptophan-d-tryptophan assembling architectures comprising alternating water and peptide layers. The extensive connection of water molecules results in significant dipole–dipole interactions and piezoelectric response that can be further engineered by doping via iodine adsorption or isotope replacement with no change in the chemical composition. This simple system and the new doping strategies supply alternative solutions for enhancing charge transfer in bioinspired supramolecular architectures.

peer-reviewed Lower back pain is a major global health challenge that can often be caused by degeneration of the Intervertebral Disc (IVD). While IVD biomechanics are a key factor in the degenerative cycle, many mechanotransduction pathways remain unknown, in particular the electro-mechanical coupling in the loaded tissue. However, despite evidence for a role in the mechanically-induced remodelling of similar tissue, piezoelectricity has been overlooked in the IVD. In this study, we investigate the piezoelectric properties of the Annulus Fibrosus (AF) and the Nucleus Pulposus (NP) by measuring the direct piezoelectric effect of mechanically-induced electrical potential change. To verify these findings, we conducted Piezoresponse Force Microscopy (PFM) to measure the inverse effect of electrically-induced deformation. We demonstrate that, for the first time, piezoelectricity is generated throughout the IVD. Piezoelectric effects were greater in the AF than the NP, owing to the organised collagen networks present. However, the piezoresponse found in the NP indicates piezoelectric properties of non-collagenous proteins that have not yet been studied. The voltage generated by longitudinal piezoelectricity in-vivo has been calculated to be ~1 nV locally, indicating that piezoelectric effects may directly affect cell alignment in the AF and may work in conjunction with streaming potentials throughout the IVD. In summary, we have highlighted an intricate electro-mechanical coupling that appears to have distinct physiological roles in the AF and NP. Further study is required to elucidate the cell response and determine the potential role of piezoelectric effects in regeneration and preventative measures from degeneration. PUBLISHED peer-reviewed

Diphenylalanine (FF) represents the simplest peptide building block that self-assembles into ordered nanostructures with interesting physical properties. Among self-assembled peptide structures, FF nanotubes display notable stiffness and piezoelectric parameters (Young’s modulus = 19–27 GPa, strain coefficient d33 = 18 pC/N). Yet, inorganic alternatives remain the major materials of choice for many applications due to higher stiffness and piezoelectricity. Here, aiming to broaden the applications of the FF motif in materials chemistry, we designed three phenyl-rich dipeptides based on the β,β-diphenyl-Ala-OH (Dip) unit: Dip-Dip, cyclo-Dip-Dip, and tert-butyloxycarbonyl (Boc)-Dip-Dip. The doubled number of aromatic groups per unit, compared to FF, produced a dense aromatic zipper network with a dramatically improved Young’s modulus of ∼70 GPa, which is comparable to aluminum. The piezoelectric strain coefficient d33 of ∼73 pC/N of such assembly exceeds that of poled polyvinylidene-fluoride (PVDF) polymers and compares well to that of lead zirconium titanate (PZT) thin films and ribbons. The rationally designed π–π assemblies show a voltage coefficient of 2–3 Vm/N, an order of magnitude higher than PVDF, improved thermal stability up to 360 °C (∼60 °C higher than FF), and useful photoluminescence with wide-range excitation-dependent emission in the visible region. Our data demonstrate that aromatic groups improve the rigidity and piezoelectricity of organic self-assembled materials for numerous applications.

Progress in nanomedicine has enabled the development of smart hybrid nanostructures (HNSs) for brain cancer theranostics, a novel platform that can diagnose the brain while concurrently beginning primary treatment, initiating secondary treatments where necessary, and monitoring the therapy response. These HNSs can release guest molecules/cargoes directly to brain tumors in response to external physical stimuli. Such physical stimulation is generally referred to as remote stimuli which can be externally applied examples include alternating magnetic field, visible or near-infrared light, ultrasound radiation, X-ray, and radiofrequency. The release of therapeutic cargoes in response to physical stimuli can be performed along with photodynamic therapy, photothermal therapy, phototriggered chemotherapeutics, sonodynamic therapy, electrothermal therapy, and magnetothermal therapy. Herein, we review different HNSs currently used as remotely triggered modalities in brain cancer, such as organic-inorganic HNSs, polymer micelles, and liposomes HNSs. We also summarize underlying mechanisms of remote triggering brain cancer therapeutics including single- and two-photon triggering, thermoresponsive HNSs, photoresponsive HNSs, magnetoresponsive HNSs, and electrically and ultrasound-stimulated HNSs. In addition to a brief synopsis of ongoing research progress on "smart" HNSs-based platforms of novel brain cancer therapeutics, the review offers an up-to-date development in this field for neuro-oncologists, material/nanoscientists, and radiologists so that a rapid clinical impact can be achieved through a convergence of multidisciplinary expertise.

The ultrasonic visibility of a biopsy needle tip is of critical importance for the success and safety of endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) procedures. The aim of this study was to design a surface topology, in silico, which enhances the ultrasound visibility of a needle by controlling and optimising the direction of the reflections. Topographic enhancements to needle surface redirect scattered waves back to the transducer to enhance needle visibility, or “echogenicity.” Echogenicity enhancement is demonstrated across insonification angles of 30°–90° on full-length scale of biopsy needles used in practice. By applying a textured surface across the full length of the needle surface, the signal being returned to the transducer can be tripled from that of a constant periodic dimple echogenic surface and seven times that of an untextured flat surface. Our first principles model provides a quantitative insight to echogenicity and its enhancement. The model allows in silico design of needles for USG-FNA and biopsy with enhanced echogenicity and consequent improvement in visibility, including but not limited to needle tip area.

Background A thorough understanding of cutting-edge geometry and cutting forces of hollow biopsy needles are required to optimise needle tip design to improve fine needle aspiration procedures. Objectives To incorporate the dynamics of needle motion in a model for flexible hollow bevel tipped needle insertion into a biological mimetic soft-gel using parameters obtained from experimental work. Additionally, the models will be verified against corresponding needle insertion experiments. Methods To verify simulation results, needle deflection and insertion forces were compared with corresponding experimental results acquired with an in-house developed needle insertion mechanical system. Additionally, contact stress distribution on needles from agar gel for various time scales were also studied. Results For the 15°, 30°, 45°, 60° bevel angle needles, and 90° blunt needle, the percentage error in needle deflection of each needle compared to experiments, were 7.3%, 9.9%, 8.6%, 7.8%, and 9.7% respectively. Varying the bevel angle at the needle tip demonstrates that the needle with a lower bevel angle produces the largest deflection, although the insertion force does not vary too much among the tested bevel angles. Conclusion This experimentally verified computer-based simulation model could be used as an alternative tool for better understanding the needle-tissue interaction to optimise needle tip design towards improved biopsy efficiency.

Background Cellulite is a common physiological condition of dermis, epidermis, and subcutaneous tissues experienced by 85 to 98% of the post-pubertal females in developed countries. Infrared (IR) thermography combined with artificial intelligence (AI)-based automated image processing can detect both early and advanced cellulite stages and open up the possibility of reliable diagnosis. Although the cellulite lesions may have various levels of severity, the quality of life of every woman, both in the physical and emotional sphere, is always an individual concern and therefore requires patient-oriented approach. Objectives The purpose of this work was to elaborate an objective, fast, and cost-effective method for automatic identification of different stages of cellulite based on IR imaging that may be used for prescreening and personalization of the therapy. Materials and methods In this study, we use custom-developed image preprocessing algorithms to automatically select cellulite regions and combine a total of 9 feature extraction methods with 9 different classification algorithms to determine the efficacy of cellulite stage recognition based on thermographic images taken from 212 female volunteers aged between 19 and 22. Results A combination of histogram of oriented gradients (HOG) and artificial neural network (ANN) enables determination of all stages of cellulite with an average accuracy higher than 80%. For primary stages of cellulite, the average accuracy achieved was more than 90%. Conclusions The implementation of computer-aided, automatic identification of cellulite severity using infrared imaging is feasible for reliable diagnosis. Such a combination can be used for early diagnosis, as well as monitoring of cellulite progress or therapeutic outcomes in an objective way. IR thermography coupled to AI sets the vision towards their use as an effective tool for complex assessment of cellulite pathogenesis and stratification, which are critical in the implementation of IR thermographic imaging in predictive, preventive, and personalized medicine (PPPM).

peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 22/06/2020 This is a pre-print of an article that was published in " Computers In Biology And Medicine" for the final version please see http://dx.doi.org/10.1016/j.compbiomed.2019.103337 Planning and practice of surgical procedures can be improved through the use of modelling. This study provides an insight into the biopsy needle (i.e. hollow cannula) and needle-tissue interactions using a modelling approach, thus enabling the optimization of needle-tip designs not only for training but also for the planning of surgical procedures. Simulations of needle insertion into agar gel were performed using a Coupled Eulerian-Lagrangian (CEL) based finite element (FE) analysis, adapted for large deformation and tissue fracture. The experimental work covers needle insertion into 3% agar gel using a needle with a beveled tip of various angles, to assess the validity of the simulation. The simulated needle deflection and insertion force for two needles (i.e. Needle 1 with 18° bevel angle and Needle 2 with 27° bevel angle) were compared with corresponding experimental results. The contact stress (i.e. contact pressure) on the needles from the agar gel during the insertion of the needles were also studied. Observations indicate that varying the needle bevel angle from 27° to 18° results in a decrease of the peak force (i.e. puncture force) and an increase in needle deflection. Quantitatively, the percentage errors between the experimental data and the FE model for the total insertion force along the z-direction (i.e. Z Force) for Needle 1 and 2 were 4% and 4.8% (p > 0.05), respectively. Similarly, needle deflection percentage errors along the x-z plane were 5.7% and 10% respectively. Therefore, the forces and needle deflection values predicted by the simulation are a close approximation of the experimental model, validating the Coupled Eulerian-Lagrangian based FE model. Thus, providing an experimentally validated model for biopsy and cytology needle design in silico that has the potential to replace the current build and break approach of needle design used by manufacturers. peer-reviewed

The ability to reliably measure electromechanical properties is crucial to the advancement of materials design for applications in fields ranging from biology and medicine to energy storage and electronics. With the relentless miniaturization of device technology, the ability to perform this characterization on the nanoscale is paramount. Due to its ability to probe electromechanical properties on the micro- and nano-scales, piezoresponse force microscopy (PFM) has become the premier tool for piezoelectric and ferroelectric characterization of a new generation of smart, functional materials. Despite its widespread use and popularity, PFM is a highly nuanced technique, and measurements on similar samples using different machines and/or in different laboratories often fail to agree. A comprehensive protocol for accurate quantitative measurements has not been presented in the literature, slowing the general uptake of the technique by reducing the ability of research groups to take full advantage of PFM for their characterization needs. Here, we present a procedure for PFM measurements, which outlines the practical aspects of quantitative PFM, from sample preparation to probe choice and use of control samples, and we substantiate these steps with original data on lithium niobate control samples. This quantitative characterization protocol is critical as society looks to smaller, greener alternatives to traditional piezoelectric materials for applications such as drug delivery, bio-microelectromechanical system sensors and actuators, and energy harvesting.

Magnetic-plasmonic, Fe3O4-Au, core-shell nanoparticles are popular in many applications, most notably in therapeutics and diagnostics, and thus, the imaging of these nanostructures in biological samples is of high importance. These nanostructures are typically imaged in biological material by dark field scatter imaging, which requires an even distribution of nanostructures in the sample and, therefore, high nanoparticle doses, potentially leading to toxicology issues. Herein, we explore the nonlinear optical properties of magnetic nanoparticles coated with various thicknesses of gold using the open aperture z-scan technique to determine the nonlinear optical properties and moreover, predict the efficacy of the nanostructures in nonlinear imaging. We find that the magnetic nanoparticles coated with gold nanoseeds and thinner gold shells (ca. 4 nm) show the largest nonlinear absorption coefficient β and imaginary part of the third-order susceptibility Im χ(3), suggesting that these nanostructures would be suitable contrast agents. Next, we combine laser dark field microscopy and epi-detected coherent anti-Stokes Raman (CARS) microscopy to image the uptake of magnetic-plasmonic nanoparticles in human pancreatic cancer cells. We show the epi-detected CARS technique is suitable for imaging of the magnetic-plasmonic nanoparticles without requiring a dense distribution of nanoparticles. This technique achieves superior nanoparticle contrasting over both epi-detected backscatter imaging and transmission dark field imaging, while also attaining label-free chemical contrasting of the cell. Lastly, we show the high biocompatibility of the Fe3O4 nanoparticles with ca. 4-nm thick Au shell at concentrations of 10–100 µg/mL.

A method is proposed to overcome the diffraction limit of spatial resolution in infrared microscopy. To achieve this, standing waves in an attenuated total reflection configuration were generated to spatially modulate the absorbance of adsorbate vibrational transitions. A numerical simulation was undertaken. It showed that chemical imaging with a spatial resolution of approximately 100 nm is achievable in the case of self-assembled patterns (ofoctdecyltrichlorosilane [CH3-(CH2)17-SiCl3]), when probing the methyl modes located near 3.5 micrometres.

Biomolecular crystals are an emerging class of piezoelectric materials that are both biocompatible and biodegradable, which enables their use in biomedical applications and smart devices while ensuring eco-friendly production and disposal. However, accurate quantification of the piezoelectric response of soft sub-micron crystals remains a significant challenge, as conventional piezoelectric measurement techniques are suited to ceramics, thin films, and polymers. Here, we demonstrate the use of a novel piezoresponse force microscopy (PFM) methodology for robust, reliable quantification of the electromechanical response of biomolecular crystals. As a strong test of high accuracy and precision, we show that PFM, integrated with quantum mechanical (QM) density functional theory (DFT) calculations, can distinguish the piezoelectric responses of near-isopiezoelectric amino acid crystals. We show that a statistical approach, combined with experimental best practices, provides effective piezoelectric coefficients of biomolecular single crystals accurately and unambiguously. This work opens the door to high-throughput screening and characterisation of natural and engineered soft piezoelectric crystals for eco-friendly energy harvesters and biodegradable medical implants, reducing dependence on lead-based and rare-earth-containing piezoelectric materials.

Second-harmonic generation (SHG) is a nonlinear optical process that can provide disease diagnosis through characterization of biological building blocks such as amino acids, peptides, and proteins. The second-order nonlinear susceptibility tensor χ(2) of a material characterizes its tendency to cause SHG. Here, a method for finding the χ(2) elements from polarization-resolved SHG microscopy in transmission mode is presented. The quantitative framework and analytical approach that corrects for micrometer-scale morphology and birefringence enable the determination and comparison of the SHG susceptibility tensors of β- and γ-phase glycine microneedles. The maximum nonlinear susceptibility coefficients are d33 = 15 pm V-1 for the β and d33 = 5.9 pm V-1 for the γ phase. The results demonstrate glycine as a useful biocompatible nonlinear material. This combination of the analytical model and polarization-resolved SHG transmission microscopy is broadly applicable for quantitative SHG material characterization and diagnostic imaging.

Optical properties of metal nanostructures, governed by the so-called localised surface plasmon resonance (LSPR) effects, have invoked intensive investigations in recent times owing to their fundamental nature and potential applications. LSPR scattering from metal nanostructures is expected to show the symmetry of the oscillation mode and the particle shape. Therefore, information on the polarisation properties of the LSPR scattering is crucial for identifying different oscillation modes within one particle and to distinguish differently shaped particles within one sample. On the contrary, the polarisation state of light itself can be arbitrarily manipulated by the inverse designed sample, known as metamaterials. Apart from polarisation state, external stimulus, e.g., magnetic field also controls the LSPR scattering from plasmonic nanostructures, giving rise to a new field of magneto-plasmonics. In this review, we pay special attention to polarisation and its effect in three contrasting aspects. First, tailoring between LSPR scattering and symmetry of plasmonic nanostructures, secondly, manipulating polarisation state through metamaterials and lastly, polarisation modulation in magneto-plasmonics. Finally, we will review recent progress in applications of plasmonic and magneto-plasmonic nanostructures and metamaterials in various fields.

This chapter aims to identify gaps in our understanding of current strengths of hybrid nanostructures in theranostics to fulfill its promise in prolonging patient survival, and to offer an overview of our current grasp of the preclinical and clinical stages of nanostructures in cancer. The chapter starts with a brief discussion of the current clinical and preclinical stages of hybrid nanostructures. Subsequently, we provide a comprehensive compilation of recent representative studies in this field, which is organized depending on the proposed clinical applications. We focus on the integration of organic–inorganic interfaces for the development of cancer therapies based on hybrid nanostructures.

As the industry and commercial market move towards the optimization of printing and additive manufacturing, it becomes important to understand how to obtain the most from the materials while maintaining the ability to print complex geometries effectively. Combining such a manufacturing method with advanced carbon materials, such as Graphene, Carbon Nanotubes, and Carbon fibers, with their mechanical and conductive properties, delivers a cutting-edge combination of low-cost conductive products. Through the process of printing the effectiveness of these properties decreases. Thorough optimization is required to determine the idealized ink functional and flow properties to ensure maximum printability and functionalities offered by carbon nanoforms. The optimization of these properties then is limited by the printability. By determining the physical properties of printability and flow properties of the inks, calculated compromises can be made for the ink design. In this review we have discussed the connection between the rheology of carbon-based inks and the methodologies for maintaining the maximum pristine carbon material properties.

Fast, label-free optical identification and quantification of biomolecules and other relevant biological materials in microfluidic devices and the vascular system will play a major role in liquid biopsy and related diagnoses. An optical microscope probing simultaneously non-linear coherent anti-Stokes Raman scattering (CARS) and linear scattering (LS) was used to probe microparticles in aqueous solutions flowed unconstrained in microfluidic channels. Despite the optical complexity of these systems, where out-of-focus microparticles randomly impede CARS and LS, and where water CARS generates a substantial background, we demonstrate that in-focus microparticles can be individually and unambiguously detected when CARS and LS are co-analyzed. The ability to chemically discriminate microscale features in optically realistic flows supports the relevance of multimodal CARS platforms for liquid biopsy.

peer-reviewed The optimum geometry for waveguide propagation was determined by comparing bowtie and semicircle antenna cuts to a standard plain waveguide with a 635 nm laser. The results of both experimental data and COMSOL simulations proved that the bowtie antenna increased waveguide output in comparison to the plain waveguide with the semicircle pattern showing no enhancement. It was also determined that the propagation was highest when the polarization direction of the laser was perpendicular to the direction of the waveguide for all patterns, while polarization along the propagation direction led to little or no output in all antenna and plain waveguide cases. The waveguide output of the bowtie antenna and plain structures was then measured using a tunable laser for wavelengths from 570 nm to 958 nm under both parallel and perpendicular polarization conditions. The results indicated that the bowtie antenna performed better over the entire range with an average increase factor of 2.12 ±0.40 over the plain waveguide pattern when perpendicularly polarized to the waveguide direction, and 1.10±0.48 when parallel. The measured values indicate that the structure could have applications in broadband devices.