Femtosecond laser programmed artificial musculoskeletal systems.

Natural musculoskeletal systems have been widely recognized as an advanced robotic model for designing robust yet flexible microbots. However, the development of artificial musculoskeletal systems at micro-nanoscale currently remains a big challenge, since it requires precise assembly of two or more materials of distinct properties into complex 3D micro/nanostructures. In this study, we report femtosecond laser programmed artificial musculoskeletal systems for prototyping 3D microbots, using relatively stiff SU-8 as the skeleton and pH-responsive protein (bovine serum albumin, BSA) as the smart muscle. To realize the programmable integration of the two materials into a 3D configuration, a successive on-chip two-photon polymerization (TPP) strategy that enables structuring two photosensitive materials sequentially within a predesigned configuration was proposed. As a proof-of-concept, we demonstrate a pH-responsive spider microbot and a 3D smart micro-gripper that enables controllable grabbing and releasing. Our strategy provides a universal protocol for directly printing 3D microbots composed of multiple materials.

Formation of long-lived reactive species of blood serum proteins induced by low-intensity irradiation of helium-neon laser and their involvement in the generation of reactive oxygen species.

It was demonstrated that low-intensity radiation of helium-neon (He-Ne) laser at 632.8nm, which leads to the transition of oxygen to a singlet state, causes the formation of reactive oxygen species (ROS) - hydrogen peroxide, hydroxyl and superoxide (hydroperoxide) radicals - in aqueous solutions. The oxygen effect - dependence of hydrogen peroxide formation on the concentration of molecular oxygen - was shown, and the participation of singlet oxygen, hydroxyl radicals and superoxide (hydroperoxide) radicals in this process was testified. Laser radiation-induced ROS in solutions of blood serum proteins, bovine serum albumin and bovine gamma-globulin, cause the formation of long-lived reactive protein species (LRPS) with a half-life of about 4h. The generation of LRPS caused by laser irradiation results in prolonged several-hour generation of ROS - hydrogen peroxide, hydroxyl and superoxide radicals. As affected by LRPS, coupled radical reactions lead to conversion of dissolved molecular oxygen to hydrogen peroxide. Irradiation with light sources away from the oxygen absorption band is not attended by formation of ROS and LRPS. A consideration is provided for the possible molecular mechanisms of ROS formation under the influence of He-Ne laser irradiation, the role of proteins in their generation and the biological significance of these processes.

Modulation of protein behavior through light responses of TiO2 nanodots films.

In this work, the behavior of protein molecules adsorbed on TiO2 nanodots films are modulated through the light responses of the nanodots. TiO2 nanodots films are first prepared through phase separation induced self assembly. Then, bovine serum albumin (BSA) is adsorbed on TiO2 nanodots films and exposed to ultraviolet (365 nm) illumination. It is found the conformation of surface-bound BSA molecules changes with ultraviolet illumination. Moreover, the BSA molecules conjugate to the surface-bound molecules, which are in the overlayer, are released. The reason is ascribed to that TiO2 nanodots absorb ultraviolet and result in the increase of surface hydroxyl groups on nanodots. Such increase further leads to intensified attraction of -NH3 groups in the surface-bound BSA molecules. That not only changes the conformation of the surface-bound BSA molecules, but also weaken the conjugation between surface-bound molecules and other BSA molecules in the overlayer. Eventually, the overlayer of BSA molecules is released. It is believed that such protein conformation variation and release behavior induced through light responses of TiO2 nanodots are crucial in understanding the biomedical performance of TiO2 nanostructures. Also, it could be widely utilized in tailoring of the materials-protein interactions.

Gel phantom study with high-intensity focused ultrasound: influence of metallic stent containing either air or fluid.

We aimed to investigate whether a cylindrical structure containing either air or fluid and with or without a metallic stent affects the volume and density of cavitation produced by high-intensity focused ultrasound via a gel phantom study. Sixteen tissue-mimicking phantoms based on a polyacrylamide gel mixed with bovine serum albumin with a cylindrical hole 1 cm in diameter and 7.5 cm in length were divided into four groups of four phantoms with air in the holes (group 1), four phantoms with fluid in the holes (group 2), four phantoms with air-containing metallic stents (group 3) and four phantoms with fluid-containing metallic stents (group 4). A pulsed high-intensity focused ultrasound beam (50% duty cycle, 40-Hz pulse repetition frequency) at 75 W of acoustic power was directed perpendicularly to the longitudinal axis of the hole, with its focus at the posterior wall of the hole. The size of the cavitation on the x-, y-, and z-axes was measured, and the volumes of cavitation and coagulation were calculated using the formula for the volume of an elliptical cone. The density of cavitation was measured in the tissue phantom anterior to the hole with a 1 × 1-cm square region of interest. For statistical analysis, the Kruskal-Wallis test and Mann-Whitney U-test were used. The phantoms with air-containing holes (groups 1 and 3) developed larger and denser cavitations anterior to the focus, without unnecessary coagulation posterior to the focus, compared with the phantoms with fluid-containing holes (groups 2 and 4), regardless of the presence of stents. All of the axes and volumes of the anterior cavitations were significantly larger than those of the posterior cavitations in groups 1 and 3 (all p-values <0.05). The results of this study might be applied to maximize cavitation to enhance drug delivery into tumors.

Structural changes of ultrasonicated bovine serum albumin revealed by hydrogen-deuterium exchange and mass spectrometry.

The structural changes of bovine serum albumin (BSA) under high-intensity ultrasonication were investigated by fluorescence spectroscopy and mass spectrometry. Evidence for the ultrasonication-induced conformational changes of BSA was provided by the intensity changes and maximum-wavelength shift in fluorescence spectrometry. Matrix-assisted laser desorption-ionization time-of-flight mass spectroscopy (MALDI-TOF MS) revealed the increased intensity of the peak at the charge state +5 and a newly emerged peak at charge state +6, indicating that the protein became unfolded after ultrasonication. Prevalent unfolding of BSA after ultrasonication was revealed by hydrogen-deuterium exchange coupled with mass spectrometry (HDX-MS). Increased intensity and duration of ultrasonication further promoted the unfolding of the protein. The unfolding induced by ultrasonication goes through an intermediate state similar to that induced by a low concentration of denaturant.

A neutron dynamic therapy with a boron tracedrug UTX-51 using a compact neutron generator.

BACKGROUND/AIM: We are developing a neutron dynamic therapy (NDT) with boron tracedrugs for a new mechanical-clearance treatment of pathotoxic misfolded, aggregated, and self-propagating prion-associated disease proteins. We present a compact neutron generator-based NDT using a boron tracedrug UTX-51. Our NDT is based on the weak thermal neutron-bombarded destructive action of UTX-51 on bovine serum albumin (BSA) using the neutron beams produced from a compact inertial electrostatic confinement fusion (IECF) neutron generator. RESULTS: BSA as an NDT molecular target was subjected to thermal neutron irradiation for eight hours using a compact neutron generator. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern showed no protein band when 2 nmoles of BSA were irradiated with more than 100 nmoles of UTX-51, while BSA was not affected when irradiated without UTX-51. CONCLUSION: For the first time, we have succeeded in the molecular destruction of a prion-disease model protein, BSA, by NDT with a boron tracedrug, UTX-51, using a compact neutron generator.

Syntheses and structural investigation of some alkali metal ion-mediated LV(V)O2(-) (L(2-) = tridentate ONO ligands) species: DNA binding, photo-induced DNA cleavage and cytotoxic activities.

Eight alkali metal ion-mediated dioxidovanadium(v), [{V(V)O2L(1-6)}A(H2O)n]∝, complexes for A = Li(+), Na(+), K(+) and Cs(+), containing tridentate aroylhydrazonate ligands coordinating via ONO donor atoms, are described. All the synthesised ligands and the metal complexes were successfully characterised by elemental analysis, IR, UV-Vis and NMR spectroscopy. X-ray crystallographic investigation of 3, 5-7 shows the presence of distorted NO4 coordination geometries for LVO2(-) in each case, and varying µ-oxido and/or µ-aqua bridging with interesting variations correlated with the size of the alkali metal ions: with small Li(+), no bridging-O is found but four ion aggregates are found with Na(+), chains for K(+) and finally, layers for Cs(+). Two (5) or three-dimensional (3, 6 and 7) architectures are consolidated by hydrogen bonding. The dioxidovanadium(v) complexes were found to exhibit DNA binding activity due to their interaction with CT-DNA by the groove binding mode, with binding constants ranging from 10(3) to 10(4) M(-1). Complexes 1-8 were also tested for DNA nuclease activity against pUC19 plasmid DNA which showed that 6 and 7 had the best DNA binding and photonuclease activity; these results support their good protein binding and cleavage activity with binding constants ranging from 10(4) to 10(5) M(-1). Finally, the in vitro antiproliferative activity of all complexes was assayed against the HeLa cell line. Some of the complexes (2, 5, 6 and 7) show considerable activity compared to commonly used chemotherapeutic drugs. The variation in cytotoxicity of the complexes is influenced by the various functional groups attached to the aroylhydrazone derivative.

Hard X-ray-induced optical luminescence via biomolecule-directed metal clusters.

Here, we demonstrate that biomolecule-directed metal clusters are applicable in the study of hard X-ray excited optical luminescence, promising a new direction in the development of novel X-ray-activated imaging probes.

Development of an albuminous reactive oxygen species assay for photosafety evaluation under experimental biomimetic conditions.

The generation of reactive oxygen species (ROS) from an ultraviolet (UV)-exposed chemical can be an experimental indicator of phototoxic potential. The aim of the present study was to develop a new ROS assay using serum albumin to provide photosafety assessment under experimental biomimetic conditions. To assess assay robustness, a validation study on an albuminous ROS (aROS) assay was conducted with a focus on intra- and inter-day precisions and Z'-factor reflecting both the assay signal-to-noise ratio and variation associated with signal measurements. In the aROS assay on quinine HCl (200 µM), a typical phototoxic drug, both intra- and inter-day precisions (coefficient of variation; CV) were found to be below 4%, and the Z'-factors for singlet oxygen and superoxide suggested a large separation band between samples and blank signals. To evaluate the prediction capacity, the aROS and ROS assays were applied to 21 phototoxins and 10 non-phototoxic chemicals. Upon aROS assay on these model chemicals, the individual specificity was 100%, and the positive and negative predictivities were found to be 100% and 81.8%, respectively. The aROS assay can be employed for poorly soluble chemicals for which the ROS assay is unavailable. Comparing the ROS assay data, there seemed to be a photochemical transition of some chemicals in albuminous solution. A molecular interaction between albumin and chemical was also assessed by UV and fluorescent spectroscopic analyses, and the results suggested the limited relationship between the albumin-chemical interaction and the photochemical change. The aROS assay may allow photosafety assessment of new drug entities with a wide range of applicability partly under experimental biomimetic conditions.

Detection of parathion pesticide by quartz crystal microbalance functionalized with UV-activated antibodies.

Photonic immobilization technique (PIT) has been used to develop an immunosensor for the detection of parathion. An antibody solution has been activated by breaking the disulfide bridge in the triad Trp/Cys-Cys through absorption of ultrashort UV laser pulses. The free thiol groups so produced interact with gold lamina making the antibody oriented upside, that is, with its variable parts exposed to the environment, thereby greatly increasing the detection efficiency. PIT has been applied to anchor polyclonal antiparathion antibodies to the gold electrode of a Quartz Crystal Microbalance (QCM) giving rise to very high detection sensitivity once the parathion is made heavier by complexion with BSA (bovine serum albumin), this latter step only required by the mass based transducer used in this case. The comparison of the sensor response with irradiated antibodies against different analytes shows that the high degree of antibody specificity is not affected by PIT nor is it by the complexion of parathion with BSA. These results pave the way to important applications in biosensing, since the widespread occurrence of the Trp/Cys-Cys residues triads in proteins make our procedure very general and effective to detect light analytes.

Preparation of visible-light-excited europium biolabels for time-resolved luminescence cell imaging application.

By using a visible-light-excited ternary Eu(3+) complex, BHHBCB-Eu(3+)-BPT (BHHBCB: 1,2-bis[4'-(1",1",1",2",2",3",3"-heptafluoro-4″,6″-hexanedion-6″-yl)-benzyl]-4-chlorosulfobenzene; BPT: 2-(N,N-diethylanilin-4-yl)-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), as a luminophore, two kinds of novel visible-light-excited europium materials, the silica-encapsulated BHHBCB-Eu(3+)-BPT (Eu@SiO2) nanoparticles and BHHBCB-Eu(3+)-BPT-conjugated bovine serum albumin (BSA-BHHBCB-Eu(3+)-BPT), were prepared for biolabeling and time-resolved luminescence cell imaging applications. The Eu@SiO2 nanoparticles, prepared by the copolymerization of 3-aminopropyl(triethoxy)silane-BHHBCB-Eu(3+)-BPT conjugate, free 3-aminopropyl(triethoxy) silane and tetraethyl orthosilicate in a water-in-oil reverse microemulsion, are monodispersed, spherical and uniform in size, and strongly luminescent with an excitation peak at ≈ 400 nm and a long luminescence lifetime of 346 µs. The BSA-BHHBCB-Eu(3+)-BPT, prepared by covalent binding of BHHBCB-Eu(3+)-BPT to BSA, shows also strong visible-light-excited luminescence with a excitation peak at ≈ 400 nm and a long luminescence lifetime of 402µs. The two materials were used for labeling transferrin and folic acid. Using the time-resolved luminescence imaging of living HeLa cells, the cell-surface receptors of transferrin and folic acid were successfully visualized by the prepared biolabels based on the ligand-receptor affinity binding interaction. The results demonstrated the feasibility of the new materials as visible-light-excited biolabels for the time-resolved luminescence cell imaging.

Light-responsive polymer nanoreactors: a source of reactive oxygen species on demand.

Various domains present the challenges of responding to stimuli in a specific manner, with the desired sensitivity or functionality, and only when required. Stimuli-responsive systems that are appropriately designed can effectively meet these challenges. Here, we introduce nanoreactors that encapsulate photosensitizer-protein conjugates in polymer vesicles as a source of "on demand" reactive oxygen species. Vesicles made of poly(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyloxazoline) successfully encapsulated the photosensitizer Rose Bengal-bovine serum albumin conjugate (RB-BSA) during a self-assembly process, as demonstrated by UV-Vis spectroscopy. A combination of light scattering and transmission electron microscopy indicated that the nanoreactors are stable over time. They serve a dual role: protecting the photosensitizer in the inner cavity and producing in situ reactive oxygen species (ROS) upon irradiation with appropriate electromagnetic radiation. Illumination with appropriate wavelength light allows us to switch on/off and to control the production of ROS. Because of the oxygen-permeable nature of the polymer membrane of vesicles, ROS escape into the environment around vesicles, as established by electron paramagnetic resonance. The light-sensitive nanoreactor is taken up by HeLa cells in a Trojan horse fashion: it is nontoxic and, when irradiated with the appropriate laser light, produces ROS that induce cell death in a precise area corresponding to the irradiation zone. These nanoreactors can be used in theranostic approaches because they can be detected via the fluorescent photosensitizer signal and simultaneously produce ROS efficiently "on demand".

Investigation of the photocatalytic effect of zinc oxide nanoparticles in the presence of nitrite.

Zinc oxide nanoparticles are widely used in sunscreen products because of their chemical stability and capability of blocking harmful ultraviolet rays. However, zinc oxide nanoparticles can also generate reactive species under ultraviolet irradiation. Because nitrite can form reactive nitrogen species under oxidative stress and because it exists in perspiration and cosmetics, we studied the effects of nitrites on the photocatalytic damage of zinc oxide nanoparticles (50 nm and 90 nm) to bovine serum albumin and human keratinocyte cells under ultraviolet irradiation (365 nm and 254 nm). The results indicate that nitrite plays an enhancing role in photocatalytic damage by breaking amino acid residues and promoting protein oxidation and nitration. The concentrations of zinc oxide and nitrite, the irradiation light and duration, and the pH of the medium are important factors influencing this photocatalytic damage. Size effects of ZnO nanoparticles on bovine serum albumin and keratinocyte cells are different. It is speculated that the extent of photo-damage is partially dependent on the aggregation of zinc oxide. These findings may be valuable for understanding potential risks of applying zinc oxide nanoparticle-containing sunscreens to human skin under sunlight exposure.

Spectroscopic analyses on sonocatalytic damage to bovine serum albumin (BSA) induced by ZnO/hydroxylapatite (ZnO/HA) composite under ultrasonic irradiation.

ZnO/hydroxylapatite (ZnO/HA) composite with HA molar content of 6.0% was prepared by the method of precipitation and heat-treated at 500°C for 40min and was characterized by powder X-ray diffraction (XRD). The sonocatalytic activities of ZnO/HA composite was carried out through the damage of bovine serum albumin (BSA) in aqueous solution. Furthermore, the effects of several factors on the damage of BSA molecules were evaluated by means of UV-vis and fluorescence spectra. Experimental results indicated that the damage degree of BSA aggravated with the increase of ultrasonic irradiation time, irradiation power and ZnO/HA addition amount, but weakened with the increase of solution acidity and ionic strength. In addition, the damage site to BSA was also studied by synchronous fluorescence technology and the damage site was mainly at tryptophan (Trp) residue. This paper provides a valuable reference for driving sonocatalytic method to treat tumor in clinic application.

Design, synthesis and destructive dynamic effects of BODIPY-containing and curcuminoid boron tracedrugs for neutron dynamic therapy.

BACKGROUND: We previously designed the boron tracedrugs UTX-42, UTX-43, and UTX-44, which possess antioxidant potency. In order to explore their destructive dynamic effects when bombarded by weak thermal neutrons, we performed thermal neutron irradiation of bovine serum albumin (BSA) treated with the boron tracedrugs. MATERIALS AND METHODS: Boron tracedrugs, including the boron dipyrromethene (BODIPY)-containing compounds UTX-42, UTX-44, and UTX-47 and the curcuminoid compounds UTX-50 and UTX-51, were designed for neutron dynamic therapy based on their molecular orbital calculation. Newly designed UTX-47, UTX-50, and UTX-51 were synthesized. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to detect decomposition by thermal neutron irradiation of BSA treated with these boron tracedrugs. RESULTS: The combination of 1.0 µM BSA with 100 µM of each of the boron tracedrugs showed a decrease in band intensity after irradiation. CONCLUSION: All boron tracedrugs tested caused destructive dynamic damage of BSA during thermal neutron irradiation, suggesting that boron tracedrugs could be used as dynamic drugs for neutron dynamic therapy.

Studies of inactivation of encephalomyocarditis virus, M13 bacteriophage, and Salmonella typhimurium by using a visible femtosecond laser: insight into the possible inactivation mechanisms.

We report experimental results on the inactivation of encephalomyocarditis virus, M13 bacteriophage, and Salmonella typhimurium by a visible femtosecond laser. Our results suggest that inactivation of virus and bacterium by a visible femtosecond laser involves completely different mechanisms. Inactivation of viruses by a visible femtosecond laser involves the breaking of hydrogen∕hydrophobic bonds or the separation of the weak protein links in the protein shell of a viral particle. In contrast, inactivation of bacteria is related to the damage of their DNAs due to irradiation of a visible femtosecond laser. Possible mechanisms for the inactivation of viruses and bacteria are discussed.

Effect of diode-laser and AC magnetic field of bovine serum albumin nanospheres loaded with phthalocyanine and magnetic particles.

This study reports on the development and characterization of bovine serum albumin (BSA) nanospheres containing Silicon(IV) phthalocyanine (NzPc) and/or maghemite nanoparticles (MNP), the latter introduced via ionic magnetic fluid (MF). The nanosized BSA-loaded samples were designed for synergic application while combining Photodynamic Therapy and Hyperthermia. Incorporation of MNP in the albumin-based template, allowing full control of the magnetic content, was accomplished by adding a highly-stable ionic magnetic fluid sample to the albumin suspension, following heat denaturing. The material's evaluation was performed using Zeta potential measurements and scanning electron microscopy. The samples were characterized by steady-state techniques and time-resolved fluorescence. The in vitro assay, using human fibroblasts, revealed no cytotoxic effect in all samples investigated, demonstrating the potential of the tested system as a synergistic drug delivery system.

Study on the sonodynamic activity and mechanism of promethazine hydrochloride by multi-spectroscopic techniques.

In this paper, the bovine serum albumin (BSA) was selected as a target molecule, the sonodynamic damage to protein in the presence of promethazine hydrochloride (PMT) and its mechanism were studied by the means of absorption, fluorescence and circular dichroism (CD) spectra. The results of hyperchromic effect of absorption spectra and quenching of intrinsic fluorescence spectra indicate that the ultrasound-induced BSA molecules damage is enhanced by PMT. The damage degree of BSA molecules increases with the increase of ultrasonic irradiation time and PMT concentration. The results of synchronous fluorescence, three-dimensional fluorescence and CD spectra confirmed that the synergistic effects of ultrasound and PMT induced the damage of BSA molecules. The results of oxidation-extraction photometry with several reactive oxygen species (ROS) scavengers indicate that the damage of BSA molecules could be mainly due to the generation of ROS and both (1)O(2) and OH are the important mediators of the ultrasound-induced BSA molecules damage in the presence of PMT.

Spectroscopic studies on interaction and sonodynamic damage of metallochlorophyllin (Chl-M (M=Fe, Zn and Cu)) to protein under ultrasonic irradiation.

In this paper, the chlorophyll derivatives, metallochlorophyllin (Chl-M) (M=Fe, Zn and Cu) including chlorophyllin iron (Chl-Fe), chlorophyllin zinc (Chl-Zn) and chlorophyllin copper (Chl-Cu), were adopted as sonosensitizers to combine with ultrasonic irradiation, and the sonodynamic damage of bovine serum albumin (BSA) was investigated. At first, the interaction of Chl-M with BSA was studied by fluorescence spectroscopy. The results show that the quenching mechanism belongs to a static process and among them the affinity of Chl-Fe to BSA is the most obvious. Then, some influence factors on the sonodynamic damage of BSA molecules in the presence of Chl-M under ultrasonic irradiation were also studied. Synchronous fluorescence spectra show that the binding and damage sites of Chl-M to BSA molecule are mainly on the tryptophan (Trp) residues. The generation of ROS in Chl-M sonodynamic process is estimated by the method of Oxidation-Extraction Spectrometry (OEP). This paper may offer some valuable references for the study of the sonodynamic activity of Chl-M and the effect of the central metals. Synchronously, it contributes to the application of Chl-M in SDT for tumor treatment.

Spectroscopic investigation on protein damage by ciprofloxacin under ultrasonic irradiation.

In recent years, sonodynamic activities of many drugs have attracted more and more attention of researchers. The correlative study will promote the development of sonodynamic therapy (SDT) in anti-tumor treatment. In this work, bovine serum albumin (BSA) was used as a protein model to investigate the intensifying effects of ciprofloxacin (CPFX) ultrasonically induced protein damage by UV-vis and fluorescence spectra. Meanwhile, the conformation of BSA is changed upon the addition of CPFX and metal ions under ultrasound (US) so that the damaging site of BSA is considered. Various influencing factors, such as US irradiation time, metal ions, solution temperature and ionic strength, on the ultrasonically induced BSA damage are discussed. It was showed that CPFX could enhance ultrasonically induced BSA damage. The damage degree of BSA was aggravated with the increasing of US irradiation time, solution temperature, ionic strength as well as the addition of metal ions. Furthermore, the reactive oxygen species (ROS) in reaction system were detected by oxidation-extraction photometry (OEP). Experimental results also showed that US could activate CPFX to produce ROS, which were mainly determined as superoxide radical anion (.O2-) and hydroxyl radical (.OH).