Laser-Synthesized Germanium Nanoparticles as Biodegradable Material for Near-Infrared Photoacoustic Imaging and Cancer Phototherapy.

Biodegradable nanomaterials can significantly improve the safety profile of nanomedicine. Germanium nanoparticles (Ge NPs) with a safe biodegradation pathway are developed as efficient photothermal converters for biomedical applications. Ge NPs synthesized by femtosecond-laser ablation in liquids rapidly dissolve in physiological-like environment through the oxidation mechanism. The biodegradation of Ge nanoparticles is preserved in tumor cells in vitro and in normal tissues in mice with a half-life as short as 3.5 days. Biocompatibility of Ge NPs is confirmed in vivo by hematological, biochemical, and histological analyses. Strong optical absorption of Ge in the near-infrared spectral range enables photothermal treatment of engrafted tumors in vivo, following intravenous injection of Ge NPs. The photothermal therapy results in a 3.9-fold reduction of the EMT6/P adenocarcinoma tumor growth with significant prolongation of the mice survival. Excellent mass-extinction of Ge NPs (7.9 L g-1 cm-1 at 808 nm) enables photoacoustic imaging of bones and tumors, following intravenous and intratumoral administrations of the nanomaterial. As such, strongly absorbing near-infrared-light biodegradable Ge nanomaterial holds promise for advanced theranostics.

Magmatism controls global oceanic transform fault topography.

Oceanic transform faults play an essential role in plate tectonics. Yet to date, there is no unifying explanation for the global trend in broad-scale transform fault topography, ranging from deep valleys to shallow topographic highs. Using three-dimensional numerical models, we find that spreading-rate dependent magmatism within the transform domain exerts a first-order control on the observed spectrum of transform fault depths. Low-rate magmatism results in deep transform valleys caused by transform-parallel tectonic stretching; intermediate-rate magmatism fully accommodates far-field stretching, but strike-slip motion induces across-transform tension, producing transform strength dependent shallow valleys; high-rate magmatism produces elevated transform zones due to local compression. Our models also address the observation that fracture zones are consistently shallower than their adjacent transform fault zones. These results suggest that plate motion change is not a necessary condition for reproducing oceanic transform topography and that oceanic transform faults are not simple conservative strike-slip plate boundaries.

Laser-Synthesized Elemental Boron Nanoparticles for Efficient Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) is one of the most appealing radiotherapy modalities, whose localization can be further improved by the employment of boron-containing nanoformulations, but the fabrication of biologically friendly, water-dispersible nanoparticles (NPs) with high boron content and favorable physicochemical characteristics still presents a great challenge. Here, we explore the use of elemental boron (B) NPs (BNPs) fabricated using the methods of pulsed laser ablation in liquids as sensitizers of BNCT. Depending on the conditions of laser-ablative synthesis, the used NPs were amorphous (a-BNPs) or partially crystallized (pc-BNPs) with a mean size of 20 nm or 50 nm, respectively. Both types of BNPs were functionalized with polyethylene glycol polymer to improve colloidal stability and biocompatibility. The NPs did not initiate any toxicity effects up to concentrations of 500 µg/mL, based on the results of MTT and clonogenic assay tests. The cells with BNPs incubated at a 10B concentration of 40 µg/mL were then irradiated with a thermal neutron beam for 30 min. We found that the presence of BNPs led to a radical enhancement in cancer cell death, namely a drop in colony forming capacity of SW-620 cells down to 12.6% and 1.6% for a-BNPs and pc-BNPs, respectively, while the relevant colony-forming capacity for U87 cells dropped down to 17%. The effect of cell irradiation by neutron beam uniquely was negligible under these conditions. Finally, to estimate the dose and regimes of irradiation for future BNCT in vivo tests, we studied the biodistribution of boron under intratumoral administration of BNPs in immunodeficient SCID mice and recorded excellent retention of boron in tumors. The obtained data unambiguously evidenced the effect of a neutron therapy enhancement, which can be attributed to efficient BNP-mediated generation of α-particles.

Boron Nanoparticle-Enhanced Proton Therapy for Cancer Treatment.

Proton therapy is one of the promising radiotherapy modalities for the treatment of deep-seated and unresectable tumors, and its efficiency can further be enhanced by using boron-containing substances. Here, we explore the use of elemental boron (B) nanoparticles (NPs) as sensitizers for proton therapy enhancement. Prepared by methods of pulsed laser ablation in water, the used B NPs had a mean size of 50 nm, while a subsequent functionalization of the NPs by polyethylene glycol improved their colloidal stability in buffers. Laser-synthesized B NPs were efficiently absorbed by MNNG/Hos human osteosarcoma cells and did not demonstrate any remarkable toxicity effects up to concentrations of 100 ppm, as followed from the results of the MTT and clonogenic assay tests. Then, we assessed the efficiency of B NPs as sensitizers of cancer cell death under irradiation by a 160.5 MeV proton beam. The irradiation of MNNG/Hos cells at a dose of 3 Gy in the presence of 80 and 100 ppm of B NPs led to a 2- and 2.7-fold decrease in the number of formed cell colonies compared to control samples irradiated in the absence of NPs. The obtained data unambiguously evidenced the effect of a strong proton therapy enhancement mediated by B NPs. We also found that the proton beam irradiation of B NPs leads to the generation of reactive oxygen species (ROS), which evidences a possible involvement of the non-nuclear mechanism of cancer cell death related to oxidative stress. Offering a series of advantages, including a passive targeting option and the possibility of additional theranostic functionalities based on the intrinsic properties of B NPs (e.g., photothermal therapy or neutron boron capture therapy), the proposed concept promises a major advancement in proton beam-based cancer treatment.

Laser-Ablative Synthesis of Silicon-Iron Composite Nanoparticles for Theranostic Applications.

The combination of photothermal and magnetic functionalities in one biocompatible nanoformulation forms an attractive basis for developing multifunctional agents for biomedical theranostics. Here, we report the fabrication of silicon-iron (Si-Fe) composite nanoparticles (NPs) for theranostic applications by using a method of femtosecond laser ablation in acetone from a mixed target combining silicon and iron. The NPs were then transferred to water for subsequent biological use. From structural analyses, it was shown that the formed Si-Fe NPs have a spherical shape and sizes ranging from 5 to 150 nm, with the presence of two characteristic maxima around 20 nm and 90 nm in the size distribution. They are mostly composed of silicon with the presence of a significant iron silicide content and iron oxide inclusions. Our studies also show that the NPs exhibit magnetic properties due to the presence of iron ions in their composition, which makes the formation of contrast in magnetic resonance imaging (MRI) possible, as it is verified by magnetic resonance relaxometry at the proton resonance frequency. In addition, the Si-Fe NPs are characterized by strong optical absorption in the window of relative transparency of bio-tissue (650-950 nm). Benefiting from such absorption, the Si-Fe NPs provide strong photoheating in their aqueous suspensions under continuous wave laser excitation at 808 nm. The NP-induced photoheating is described by a photothermal conversion efficiency of 33-42%, which is approximately 3.0-3.3 times larger than that for pure laser-synthesized Si NPs, and it is explained by the presence of iron silicide in the NP composition. Combining the strong photothermal effect and MRI functionality, the synthesized Si-Fe NPs promise a major advancement of modalities for cancer theranostics, including MRI-guided photothermal therapy and surgery.

Impact of Plasmonic Nanoparticles on Poikilocytosis and Microrheological Properties of Erythrocytes.

Plasmonic nanoparticles (NP) possess great potential in photothermal therapy and diagnostics. However, novel NP require a detailed examination for potential toxicity and peculiarities of interaction with cells. Red blood cells (RBC) are important for NP distribution and the development of hybrid RBC-NP delivery systems. This research explored RBC alterations induced by noble (Au and Ag) and nitride-based (TiN and ZrN) laser-synthesized plasmonic NP. Optical tweezers and conventional microscopy modalities indicated the effects arising at non-hemolytic levels, such as RBC poikilocytosis, and alterations in RBC microrheological parameters, elasticity and intercellular interactions. Aggregation and deformability significantly decreased for echinocytes independently of NP type, while for intact RBC, all NP except Ag NP increased the interaction forces but had no effect on RBC deformability. RBC poikilocytosis promoted by NP at concentration 50 µg mL-1 was more pronounced for Au and Ag NP, compared to TiN and ZrN NP. Nitride-based NP demonstrated better biocompatibility towards RBC and higher photothermal efficiency than their noble metal counterparts.

Porous Co-Pt Nanoalloys for Production of Carbon Nanofibers and Composites.

The controllable synthesis of carbon nanofibers (CNF) and composites based on CNF (Metals/CNF) is of particular interest. In the present work, the samples of CNF were produced via ethylene decomposition over Co-Pt (0-100 at.% Pt) microdispersed alloys prepared by a reductive thermolysis of multicomponent precursors. XRD analysis showed that the crystal structure of alloys in the composition range of 5-35 at.% Pt corresponds to a fcc lattice based on cobalt (Fm-3m), while the CoPt (50 at.% Pt) and CoPt3 (75 at.% Pt) samples are intermetallics with the structure P4/mmm and Pm-3m, respectively. The microstructure of the alloys is represented by agglomerates of polycrystalline particles (50-150 nm) interconnected by the filaments. The impact of Pt content in the Co1-xPtx samples on their activity in CNF production was revealed. The interaction of alloys with ethylene is accompanied by the generation of active particles on which the growth of nanofibers occurs. Plane Co showed low productivity (~5.5 g/gcat), while Pt itself exhibited no activity at all. The addition of 15-25 at.% Pt to cobalt catalyst leads to an increase in activity by 3-5 times. The maximum yield of CNF reached 40 g/gcat for Co0.75Pt0.25 sample. The local composition of the active alloyed particles and the structural features of CNF were explored.

Transition metal dichalcogenide nanospheres for high-refractive-index nanophotonics and biomedical theranostics.

Recent developments in the area of resonant dielectric nanostructures have created attractive opportunities for concentrating and manipulating light at the nanoscale and the establishment of the new exciting field of all-dielectric nanophotonics. Transition metal dichalcogenides (TMDCs) with nanopatterned surfaces are especially promising for these tasks. Still, the fabrication of these structures requires sophisticated lithographic processes, drastically complicating application prospects. To bridge this gap and broaden the application scope of TMDC nanomaterials, we report here femtosecond laser-ablative fabrication of water-dispersed spherical TMDC (MoS2 and WS2) nanoparticles (NPs) of variable size (5 to 250 nm). Such NPs demonstrate exciting optical and electronic properties inherited from TMDC crystals, due to preserved crystalline structure, which offers a unique combination of pronounced excitonic response and high refractive index value, making possible a strong concentration of electromagnetic field in the NPs. Furthermore, such NPs offer additional tunability due to hybridization between the Mie and excitonic resonances. Such properties bring to life a number of nontrivial effects, including enhanced photoabsorption and photothermal conversion. As an illustration, we demonstrate that the NPs exhibit a very strong photothermal response, much exceeding that of conventional dielectric nanoresonators based on Si. Being in a mobile colloidal state and exhibiting superior optical properties compared to other dielectric resonant structures, the synthesized TMDC NPs offer opportunities for the development of next-generation nanophotonic and nanotheranostic platforms, including photothermal therapy and multimodal bioimaging.

Laser-ablative aqueous synthesis and characterization of elemental boron nanoparticles for biomedical applications.

Boron-based nano-formulations look very promising for biomedical applications, including photo- and boron neutron capture therapies, but the fabrication of non-toxic water-dispersible boron nanoparticles (NPs), which contain the highest boron atom concentration, is difficult using currently available chemical and plasma synthesis methods. Here, we demonstrate purely aqueous synthesis of clean boron NPs by methods of femtosecond laser ablation from a solid boron target in water, thus free of any toxic organic solvents, and characterize their properties. We show that despite highly oxidizing water ambience, the laser-ablative synthesis process follows an unusual scenario leading to the formation of boron NPs together with boric acid (H3BO3) as an oxidation by-product coating the nanoparticles, which acts to stabilize the elemental boron NPs dispersion. We then demonstrate the purification of boron NPs from residual boric acid in deionized water, followed by their coating with polyethylene glycol to improve colloidal stability and biocompatibility. It was found that the formed NPs have a spherical shape with averaged size of about 37 nm, and are composed of elemental boron in mostly amorphous phase with the presence of certain crystalline fraction. The synthesized NPs demonstrate low toxicity and exhibit strong absorption in the NIR window of relative tissue transparency, promising their use in photoacoustic imaging and phototherapy, in addition to their promise for neutron capture therapy. This combined potential ability of generating imaging and therapy functionalities makes laser-synthesized B NPs a very promising multifunctional agent for biomedical applications.

Synthesis of Titanium Nitride Nanoparticles by Pulsed Laser Ablation in Different Aqueous and Organic Solutions.

Owing to a strong photothermal response in the near-IR spectral range and very low toxicity, titanium nitride (TiN) nanoparticles (NPs) synthesized by pulsed laser ablation in liquids (PLAL) present a novel appealing object for photo-induced therapy of cancer, but the properties of these NPs still require detailed investigation. Here, we have elaborated methods of femtosecond laser ablation from the TiN target in a variety of liquid solutions, including acetonitrile, dimethylformamide, acetone, water, and H2O2, to synthesize TiN NPs and clarify the effect of liquid type on the composition and properties of the formed NPs. The ablation in all solvents led to the formation of spherical NPs with a mean size depending on the liquid type, while the composition of the NPs ranged from partly oxidized TiN to almost pure TiO2, which conditioned variations of plasmonic peak in the region of relative tissue transparency (670-700 nm). The degree of NP oxidation depended on the solvent, with much stronger oxidation for NPs prepared in aqueous solutions (especially in H2O2), while the ablation in organic solvents resulted in a partial formation of titanium carbides as by-products. The obtained results contribute to better understanding of the processes in reactive PLAL and can be used to design TiN NPs with desired properties for biomedical applications.

Laser Synthesized Core-Satellite Fe-Au Nanoparticles for Multimodal In Vivo Imaging and In Vitro Photothermal Therapy.

Hybrid multimodal nanoparticles, applicable simultaneously to the noninvasive imaging and therapeutic treatment, are highly demanded for clinical use. Here, Fe-Au core-satellite nanoparticles prepared by the method of pulsed laser ablation in liquids were evaluated as dual magnetic resonance imaging (MRI) and computed tomography (CT) contrast agents and as sensitizers for laser-induced hyperthermia of cancer cells. The biocompatibility of Fe-Au nanoparticles was improved by coating with polyacrylic acid, which provided excellent colloidal stability of nanoparticles with highly negative ζ-potential in water (-38 ± 7 mV) and retained hydrodynamic size (88 ± 20 nm) in a physiological environment. The ferromagnetic iron cores offered great contrast in MRI images with r2 = 11.8 ± 0.8 mM-1 s-1 (at 1 T), while Au satellites showed X-ray attenuation in CT. The intravenous injection of nanoparticles enabled clear tumor border visualization in mice. Plasmonic peak in the Fe-Au hybrids had a tail in the near-infrared region (NIR), allowing them to cause hyperthermia under 808 nm laser exposure. Under NIR irradiation Fe-Au particles provided 24.1 °C/W heating and an IC50 value below 32 µg/mL for three different cancer cell lines. Taken together, these results show that laser synthesized Fe-Au core-satellite nanoparticles are excellent theranostic agents with multimodal imaging and photothermal capabilities.

Laser-Ablative Synthesis of Ultrapure Magneto-Plasmonic Core-Satellite Nanocomposites for Biomedical Applications.

The combination of magnetic and plasmonic properties at the nanoscale promises the development of novel synergetic image-guided therapy strategies for the treatment of cancer and other diseases, but the fabrication of non-contaminated magneto-plasmonic nanocomposites suitable for biological applications is difficult within traditional chemical methods. Here, we describe a methodology based on laser ablation from Fe target in the presence of preliminarily ablated water-dispersed Au nanoparticles (NPs) to synthesize ultrapure bare (ligand-free) core-satellite nanostructures, consisting of large (several tens of nm) Fe-based core decorated by small (mean size 7.5 nm) Au NPs. The presence of the Fe-based core conditions a relatively strong magnetic response of the nanostructures (magnetization of >12.6 emu/g), while the Au NPs-based satellite shell provides a broad extinction peak centered at 550 nm with a long tale in the near-infrared to overlap with the region of relative tissue transparency (650-950 nm). We also discuss possible mechanisms responsible for the formation of the magnetic-plasmonic nanocomposites. We finally demonstrate a protocol to enhance colloidal stability of the core-satellites in biological environment by their coating with different polymers. Exempt of toxic impurities and combining strong magnetic and plasmonic responses, the formed core-satellite nanocomposites can be used in biomedical applications, including photo- and magneto-induced therapies, magnetic resonance imaging or photoacoustic imaging.

Silicon-Gold Nanoparticles Affect Wharton's Jelly Phenotype and Secretome during Tri-Lineage Differentiation.

Multiple studies have demonstrated that various nanoparticles (NPs) stimulate osteogenic differentiation of mesenchymal stem cells (MSCs) and inhibit adipogenic ones. The mechanisms of these effects are not determined. The aim of this paper was to estimate Wharton's Jelly MSCs phenotype and humoral factor production during tri-lineage differentiation per se and in the presence of silicon-gold NPs. Silicon (SiNPs), gold (AuNPs), and 10% Au-doped Si nanoparticles (SiAuNPs) were synthesized by laser ablation, characterized, and studied in MSC cultures before and during differentiation. Humoral factor production (n = 41) was analyzed by Luminex technology. NPs were nontoxic, did not induce ROS production, and stimulated G-CSF, GM-CSF, VEGF, CXCL1 (GRO) production in four day MSC cultures. During MSC differentiation, all NPs stimulated CD13 and CD90 expression in osteogenic cultures. MSC differentiation resulted in a decrease in multiple humoral factor production to day 14 of incubation. NPs did not significantly affect the production in chondrogenic cultures and stimulated it in both osteogenic and adipogenic ones. The major difference in the protein production between osteogenic and adipogenic MSC cultures in the presence of NPs was VEGF level, which was unaffected in osteogenic cells and 4-9 times increased in adipogenic ones. The effects of NPs decreased in a row AuNPs > SiAuNPs > SiNPs. Taken collectively, high expression of CD13 and CD90 by MSCs and critical level of VEGF production can, at least, partially explain the stimulatory effect of NPs on MSC osteogenic differentiation.

Comparative Evaluation of Engineered Polypeptide Scaffolds in HER2-Targeting Magnetic Nanocarrier Delivery.

Targeted drug delivery is one of the most intriguing and challenging issues in modern biomedicine. For active targeting, full-size IgG molecules (150 kDa) are usually used. Recent studies have revealed that small artificial polypeptide scaffolds such as DARPins (14 kDa) and affibodies (8 kDa) are much more promising tools for drug delivery due to their small size, artificial nature, low immunogenicity, and many other properties. However, there is no comparative information on the targeting abilities of scaffold polypeptides, which should be taken into account when developing drug delivery systems (DDSs). The present work is the first comprehensive study on the comparison of the effectiveness of different HER2-targeting proteins within the architecture of nanoparticles. Namely, we synthesized trimodal nanoparticles: magnetic, fluorescent, and directed toward HER2 oncomarker on cancer cells. The magnetic particles (MPs) were covalently modified with (i) full-size IgG, 150 kDa, (ii) DARPin_G3, 14 kDa, and (iii) affibody ZHER2:342, 8 kDa. We showed that the number of DARPin_G3 and affibody ZHER2:342 molecules conjugated to the nanoparticle surface are 10 and 40 times higher, respectively, than the corresponding value for trastuzumab. Using the methods of magnetic particle quantification (MPQ)-cytometry and confocal microscopy, we showed that all types of the obtained magnetic conjugates specifically labeled HER2-overexpressing cells. Namely, we demonstrated that particle binding to HER2-positive cells is 1113 ± 39 fg/cell for MP*trastuzumab, 1431 ± 186 fg/cell for MP*ZHER2:342, and 625±21 fg/cell for MP*DARPin_G3, which are 2.77, 2.75, and 2.30 times higher than the corresponding values for control HER2-negative cells. Thus, we showed that the smallest HER2-recognizing polypeptide affibody ZHER2:342 is more effective in terms of specificity and selectivity in nanoparticle-mediated cell labeling.

Laser Ablation-Assisted Synthesis of Plasmonic Si@Au Core-Satellite Nanocomposites for Biomedical Applications.

Owing to strong plasmonic absorption and excellent biocompatibility, gold nanostructures are among best candidates for photoacoustic bioimaging and photothermal therapy, but such applications require ultrapure Au-based nanoformulations of complex geometry (core-shells, nanorods) in order to shift the absorption band toward the region of relative tissue transparency (650-1000 nm). Here, we present a methodology for the fabrication of Si@Au core-satellite nanostructures, comprising of a Si core covered with small Au nanoparticles (NP), based on laser ablative synthesis of Si and Au NPs in water/ethanol solutions, followed by a chemical modification of the Si NPs by 3-aminopropyltrimethoxysilane (APTMS) and their subsequent decoration by the Au NPs. We show that the formed core-satellites have a red-shifted plasmonic absorption feature compared to that of pure Au NPs (520 nm), with the position of the peak depending on APTMS amount, water-ethanol solvent percentage and Si-Au volume ratio. As an example, even relatively small 40-nm core-satellites (34 nm Si core + 4 nm Au shell) provided a much red shifted peak centered around 610 nm and having a large tail over 700 nm. The generation of the plasmonic peak is confirmed by modeling of Si@Au core-shells of relevant parameters via Mie theory. Being relatively small and exempt of any toxic impurity due to ultraclean laser synthesis, the Si@Au core-satellites promise a major advancement of imaging and phototherapy modalities based on plasmonic properties of nanomaterials.

Laser-synthesized TiN nanoparticles for biomedical applications: Evaluation of safety, biodistribution and pharmacokinetics.

Having plasmonic absorption within the biological transparency window, titanium nitride (TiN) nanoparticles (NPs) can potentially outperform gold counterparts in phototheranostic applications, but characteristics of available TiN NPs are still far from required parameters. Recently emerged laser-ablative synthesis opens up opportunities to match these parameters as it makes possible the production of ultrapure low size-dispersed spherical TiN NPs, capable of generating a strong phototherapy effect under 750-800 nm excitation. This study presents the first assessment of toxicity, biodistribution and pharmacokinetics of laser-synthesized TiN NPs. Tests in vitro using 8 cell lines from different tissues evidenced safety of both as-synthesized and PEG-coated NPs (TiN-PEG NPs). After systemic administration in mice, they mainly accumulated in liver and spleen, but did not cause any sign of toxicity or organ damage up to concentration of 6 mg kg-1, which was confirmed by the invariability of blood biochemical parameters, weight and hemotoxicity examination. The NPs demonstrated efficient passive accumulation in EMT6/P mammary tumor, while concentration of TiN-PEG NPs was 2.2-fold higher due to "stealth" effect yielding 7-times longer circulation in blood. The obtained results evidence high safety of laser-synthesized TiN NPs for biological systems, which promises a major advancement of phototheranostic modalities on their basis.

Nonlinear photoacoustic response of suspensions of laser-synthesized plasmonic titanium nitride nanoparticles.

A nonlinear photoacoustic (PA) response from solutions of 40 nm plasmonic titanium nitride nanoparticles (NPs) synthesized by laser ablation in a liquid environment (acetone) is reported. Using a photoacoustic Z-scan with 5 ns pumping pulses, values of effective nonlinear absorption (NLA) coefficients ßPA,eff were measured and found to be 3.27±0.17 × 10-8, 6.41±0.32 × 10-8, and 3.22±0.16 × 10-8 for 600, 700, and 800 nm pumping wavelengths, respectively. To take into account the influence of nonlinear scattering, absorption-dependent PA measurements were carried out together with the optical Z-scan, and the obtained data were compared. The origin of the effective absorptive nonlinearity is discussed based on combined NLA in NPs, nonlinear scattering, and bubble generation triggered by NP-mediated light absorption. Potential applications include biomedical diagnostics and therapy.

Preparation of porous Co-Pt alloys for catalytic synthesis of carbon nanofibers.

A simple and convenient procedure for the production of highly dispersed porous Co-Pt alloys to be used as catalysts for the synthesis of nanostructured carbon fibers (CNF) has been developed. The technique is based on the thermal decomposition of specially synthesized multicomponent precursors in a reducing atmosphere. A series of porous single-phase alloys Co-Pt (10-75 at% Pt) have been synthesized. The alloys containing 75 and 50 at% Pt were identified by the x-ray diffraction analysis as the intermetallics CoPt3 and CoPt, respectively. Within the region of 10-35 at% Pt, the synthesized alloys are represented by Co1-x Pt x random solid solutions with face-centered cubic lattice. The alloys obtained are characterized by a porous structure consisting of assembled fragments with a size of 50-150 nm. The obtained alloys were tested in the catalytic chemical vapor deposition of the ethylene to CNF. A significant synergistic effect between Co and Pt in the synthesis of carbon nanomaterials (CNMs) was revealed. The yield of CNF (for 30 min reaction) for catalysts containing 25-35 at% Pt was 30-38 g(CNF)/g(cat), whereas those for Co (100%) and Pt (100%) samples were as low as 5.6 and >0.1 g(CNF)/g(cat), respectively. The produced CNM composed of fibers with a segmented structure was shown to be characterized by a rather high specific surface area (200-250 m2 g-1) and structural homogeneity.

Laser-Ablative Synthesis of Stable Aqueous Solutions of Elemental Bismuth Nanoparticles for Multimodal Theranostic Applications.

Elemental bismuth (Bi) nanoparticles (NPs), with the high atomic density of the Bi nuclei, could serve as efficient targeted agents for cancer treatment, with applications such as contrast agents for computed tomography (CT) imaging, sensitizers for image-guided X-ray radiotherapy, and photothermal therapy. However, the synthesis of elemental Bi NPs suitable for biological applications is difficult using conventional chemical routes. Here, we explore the fabrication of ultrapure Bi-based nanomaterials by femtosecond laser ablation from a solid Bi target in ambient liquids and characterize them by a variety of techniques, including TEM, SEM, XRD, FTIR, Raman, and optical spectroscopy. We found that laser-ablative synthesis using an elemental Bi solid target leads to the formation of spherical Bi NPs having the mean size of 20-50 nm and a low size-dispersion. The NPs prepared in water experience a fast (within a few minutes) conversion into 400-500 nm flake-like nanosheets, composed of bismuth subcarbonates, (BiO)2CO3 and (BiO)4CO3(OH)2, while the NPs prepared in acetone demonstrate high elemental stability. We introduce a procedure to obtain a stable aqueous solution of elemental Bi NPs suitable for biological applications, based on the coating of Bi NPs prepared in acetone with Pluronic® F68 and their subsequent transfer to water. We also show that the laser-synthesized elemental Bi NPs, due to their vanishing band gap, exhibit remarkable absorption in the infrared range, which can be used for the activation of photothermal therapy in the near IR-to-IR window with maximum optical transparency in biological media. Exempt of any toxic synthetic by-products, laser-ablated elemental Bi NPs present a novel appealing nanoplatform for combination image-guided photoradiotherapies.

Laser- synthesized TiN nanoparticles as promising plasmonic alternative for biomedical applications.

Exhibiting a red-shifted absorption/scattering feature compared to conventional plasmonic metals, titanium nitride nanoparticles (TiN NPs) look as very promising candidates for biomedical applications, but these applications are still underexplored despite the presence of extensive data for conventional plasmonic counterparts. Here, we report the fabrication of ultrapure, size-tunable TiN NPs by methods of femtosecond laser ablation in liquids and their biological testing. We show that TiN NPs demonstrate strong and broad plasmonic peak around 640-700 nm with a significant tail over 800 nm even for small NPs sizes (<7 nm). In vitro tests of laser-synthesized TiN NPs on cellular models evidence their low cytotoxicity and excellent cell uptake. We finally demonstrate a strong photothermal therapy effect on U87-MG cancer cell cultures using TiN NPs as sensitizers of local hyperthermia under near-infrared laser excitation. Based on absorption band in the region of relative tissue transparency and acceptable biocompatibility, laser-synthesized TiN NPs promise the advancement of biomedical modalities employing plasmonic effects, including absorption/scattering contrast imaging, photothermal therapy, photoacoustic imaging and SERS.