Barium titanate core--gold shell nanoparticles for hyperthermia treatments

Gold-seeded Lithium Niobate Nanoparticles: Influence of Gold Surface Coverage on Second Harmonic Properties

Hybrid nanoparticles composed of an efficient nonlinear optical core and a gold shell can enhance and tune the nonlinear optical emission thanks to the plasmonic effect. However the influence of an incomplete gold shell, i.e., isolated gold nano-islands, is still not well studied. Here LiNbO₃ (LN) core nanoparticles of 45 nm were coated with various densities of gold nano-seeds (AuSeeds). As both LN and AuSeeds bear negative surface charge, a positively-charged polymer was first coated onto LN. The number of polymer chains per LN was evaluated at 1210 by XPS and confirmed by fluorescence titration. Then, the surface coverage percentage of AuSeeds onto LN was estimated to a maximum of 30% using ICP-AES. The addition of AuSeeds was also accompanied with surface charge reversal, the negative charge increasing with the higher amount of AuSeeds. Finally, the first hyperpolarizability decreased with the increase of AuSeeds density while depolarization values for Au-seeded LN were close to the one of bare LN, showing a predominance of the second harmonic volumic contribution.

Optical Detection of Denatured Ferritin Protein via Plasmonic Gold Nanoparticles Exposure through Aminosilane Solution

The presence of denatured proteins within a therapeutic drug product can create a series of serious adverse effects, such as mild irritation, immunogenicity, anaphylaxis, or instant death to a patient. The detection of protein degradation is complicated and expensive due to current methods associated with expensive instrumentation, reagents, and processing time. We have demonstrated here a platform for visual biosensing of denatured proteins that is fast, low cost, sensitive, and user friendly by exploiting the plasmonic properties of noble metal nanoparticles. In this study we have exposed artificially heat stressed ferritin and gold nanoparticles to 3-aminopropyl triethoxysilane, which degrades the protein by showing a systematic blue shift in the absorbance spectra of the gold nanoparticle/ferritin and aminosilane solution. This blue shift in absorbance produces a detectable visual color transition from a blue color to a purple hue. By studying the Raman spectroscopy of the gold nanoparticle/ferritin and aminosilane solution, the extent of ferritin degradation was quantified. The degradation of ferritin was again confirmed using dynamic light scattering and was attributed to the aggregation of the ferritin due to accelerated heat stress. We have successfully demonstrated a proof of concept for visually detecting ferritin from horse spleen that has experienced various levels of degradation, including due to heat stress.

Subchronic and chronic toxicity evaluation of inorganic nanoparticles for delivery applications

Inorganic nanoparticles provide the opportunity to localize bioactive agents to the target sites and protect them from degradation. In many cases, acute toxicities of inorganic nanoparticles used for delivery applications have been investigated. However, little information is available regarding the long-term toxicity of such materials. This review focuses on the importance of subchronic and chronic toxicity assessment of inorganic nanoparticles investigated for delivery applications. We have attempted to provide a comprehensive review of the available literature for chronic toxicity assessment of inorganic nanoparticles. Where possible correlations are made between particle composition, physiochemical properties, duration, frequency and route of administration, as well as the sex of animals, with tissue and blood toxicity, immunotoxicity and genotoxicity. A critical gap analysis is provided and important factors that need to be considered for long-term toxicology of inorganic nanoparticles are discussed.

BaTiO3-core Au-shell nanoparticles for photothermal therapy and bimodal imaging

We report sub-100 nm metal-shell (Au) dielectric-core (BaTiO₃) nanoparticles with bimodal imaging abilities and enhanced photothermal effects. The nanoparticles efficiently absorb light in the near infrared range of the spectrum and convert it to heat to ablate tumors. Their BaTiO₃ core, a highly ordered non-centrosymmetric material, can be imaged by second harmonic generation, and their Au shell generates two-photon luminescence. The intrinsic dual imaging capability allows investigating the distribution of the nanoparticles in relation to the tumor vasculature morphology during photothermal ablation. Our design enabled in vivo real-time tracking of the BT-Au-NPs and observation of their thermally-induced effect on tumor vessels.

STATEMENT OF SIGNIFICANCE

Photothermal therapy induced by plasmonic nanoparticles has emerged as a promising approach to treating cancer. However, the study of the role of intratumoral nanoparticle distribution in mediating tumoricidal activity has been hampered by the lack of suitable imaging techniques. This work describes metal-shell (Au) dielectric-core (BaTiO₃) nanoparticles (abbreviated as BT-Au-NP) for photothermal therapy and bimodal imaging. We demonstrated that sub-100 nm BT-Au-NP can efficiently absorb near infrared light and convert it to heat to ablate tumors. The intrinsic dual imaging capability allowed us to investigate the distribution of the nanoparticles in relation to the tumor vasculature morphology during photothermal ablation, enabling in vivo real-time tracking of the BT-Au-NPs and observation of their thermally-induced effect on tumor vessels.

Piezoelectric Effects of Materials on Bio-Interfaces

Electrical stimulation of cells and tissues is an important approach of interaction with living matter, which has been traditionally exploited in the clinical practice for a wide range of pathological conditions, in particular, related to excitable tissues. Standard methods of stimulation are, however, often invasive, being based on electrodes and wires used to carry current to the intended site. The possibility to achieve an indirect electrical stimulation, by means of piezoelectric materials, is therefore of outstanding interest for all the biomedical research, and it emerged in the latest decade as a most promising tool in many bioapplications. In this paper, we summarize the most recent achievements obtained by our group and by others in the exploitation of piezoelectric nanoparticles and nanocomposites for cell stimulation, describing the important implications that these studies present in nanomedicine and tissue engineering. A particular attention will be also dedicated to the physical modeling, which can be extremely useful in the description of the complex mechanisms involved in the mechanical/electrical transduction, yet also to gain new insights at the base of the observed phenomena.

Polypeptide-Based Gold Nanoshells for Photothermal Therapy

Targeted killing of cancer cells by engineered nanoparticles holds great promise for noninvasive photothermal therapy applications. We present the design and generation of a novel class of gold nanoshells with cores composed of self-assembled block copolypeptide vesicles with photothermal properties. Specifically, poly(L-lysine)₆₀- block-poly(L-leucine)₂₀ (K₆₀L₂₀) block copolypeptide vesicles coated with a thin layer of gold demonstrate enhanced absorption of light due to surface plasmon resonance (SPR) in the near-infrared range. We show that the polypeptide-based K₆₀L₂₀ gold nanoshells have low toxicity in the absence of laser exposure, significant heat generation upon exposure to near-infrared light, and, as a result, localized cytotoxicity within the region of laser irradiation in vitro. To gain a better understanding of our gold nanoshells in the context of photothermal therapy, we developed a comprehensive mathematical model for heat transfer and experimentally validated this model by predicting the temperature as a function of time and position in our experimental setup. This model can be used to predict which parameters of our gold nanoshells can be manipulated to improve heat generation for tumor destruction. To our knowledge, our results represent the first ever use of block copolypeptide vesicles as the core material of gold nanoshells.

Barium titanate nanoparticles: promising multitasking vectors in nanomedicine

Ceramic materials based on perovskite-like oxides have traditionally been the object of intense interest for their applicability in electrical and electronic devices. Due to its high dielectric constant and piezoelectric features, barium titanate (BaTiO3) is probably one of the most studied compounds of this family. Recently, an increasing number of studies have been focused on the exploitation of barium titanate nanoparticles (BTNPs) in the biomedical field, owing to the high biocompatibility of BTNPs and their peculiar non-linear optical properties that have encouraged their use as nanocarriers for drug delivery and as label-free imaging probes. In this review, we summarize all the recent findings about these 'smart' nanoparticles, including the latest, most promising potential as nanotransducers for cell stimulation.

Femtosecond-Laser-Pulse Characterization and Optimization for CARS Microscopy

We present a simple method and its experimental implementation to determine the pulse durations and linear chirps of the pump-and-probe pulse and the Stokes pulse in a coherent anti-Stokes Raman scattering microscope at sample level without additional autocorrelators. Our approach exploits the delay line, ubiquitous in such microscopes, to perform a convolution of the pump-and-probe and Stokes pulses as a function of their relative delay and it is based on the detection of the photons emitted from an appropriate non-linear sample. The analysis of the non-resonant four-wave-mixing and sum-frequency-generation signals allows for the direct retrieval of the pulse duration on the sample and the linear chirp of each pulse. This knowledge is crucial in maximizing the spectral-resolution and contrast in CARS imaging.

Two-Photon Lithography of 3D Nanocomposite Piezoelectric Scaffolds for Cell Stimulation

In this letter, we report on the fabrication, the characterization, and the in vitro testing of structures suitable for cell culturing, prepared through two-photon polymerization of a nanocomposite resist. More in details, commercially available Ormocomp has been doped with piezoelectric barium titanate nanoparticles, and bioinspired 3D structures resembling trabeculae of sponge bone have been fabricated. After an extensive characterization, preliminary in vitro testing demonstrated that both the topographical and the piezoelectric cues of these scaffolds are able to enhance the differentiation process of human SaOS-2 cells.

Nanopharmacology in translational hematology and oncology

Nanoparticles have displayed considerable promise for safely delivering therapeutic agents with miscellaneous therapeutic properties. Current progress in nanotechnology has put forward, in the last few years, several therapeutic strategies that could be integrated into clinical use by using constructs for molecular diagnosis, disease detection, cytostatic drug delivery, and nanoscale immunotherapy. In the hope of bringing the concept of nanopharmacology toward a viable and feasible clinical reality in a cancer center, the present report attempts to present the grounds for the use of cell-free nanoscale structures for molecular therapy in experimental hematology and oncology.