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Plasmonic substrates have been extensively investigated due to their potential applications in fluorescence microscopy, chemical sensing, and photochemical reactions. The optical properties of the substrate depend on the spatial and temporal features of the plasmon excited. Hence, the ability to directly visualize plasmon dynamics is crucial. In this study, we investigated the spatial and temporal properties of plasmon excitation in a plasmonic nanobowl substrate consisting of a periodic hexagonal array of nanoscale bowl-like structures developed with self-assembly. Near-field transmission imaging revealed that multiple plasmon resonance bands are observed from visible to near-infrared spectral region, and the optical contrast of the image is dependent on the observed band. Near-field two-photon photoluminescence microscopy revealed that the probability of excitation inside each nanoscale bowl-like structure is greater than that in the surrounding area. Near-field time-resolved imaging revealed that the nanobowl substrate exhibited a substantially long plasmon dephasing time, exceeding 12 fs. Based on the spectral features of the near-field and far-field spectra, we found that optically dark plasmon mode is excited by the near-field illumination and only partly contributes to the long dephasing time observed. This fact indicates that the dephasing time is extended by some other mechanism in the periodic substrate. We revealed from this study that the enhanced optical fields induced in the nanobowl structure originate from the photosynergetic effect of the cavity mode and plasmon mode excited.
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The light-induced force and convection can be enhanced by the collective effect of electrons (superradiance and red shift) in high-density metallic nanoparticles, leading to macroscopic assembly of target molecules. We here demonstrate application of the light-induced assembly for drug delivery system with enhancement of cell membrane accumulation and penetration of biofunctional molecules including cell-penetrating peptides (CPPs) with superradiance-mediated photothermal convection. For induction of photothermal assembly around targeted living cells in cell culture medium, infrared continuous-wave laser light was focused onto high-density gold-particle-bound glass bottom dishes exhibiting plasmonic superradiance or thin gold-film-coated glass bottom dishes. In this system, the biofunctional molecules can be concentrated around the targeted living cells and internalized into them only by 100 s laser irradiation. Using this simple approach, we successfully achieved enhanced cytosolic release of the CPPs and apoptosis induction using a pro-apoptotic domain with a very low peptide concentration (nM level) by light-induced condensation.
Assuntos
Sistemas de Liberação de Medicamentos , Nanopartículas Metálicas , Linhagem Celular Tumoral , Luz , Ouro/químicaRESUMO
Spin-orbit interaction is a crucial issue in the field of nanoscale physics and chemistry. Here, we theoretically demonstrate that the spin angular momentum (SAM) can accelerate and decelerate the orbital motion of nanoparticles (NPs) via light-induced interparticle interactions by a circularly polarized optical vortex. The Laguerre-Gaussian beam as a conventional optical vortex with orbital angular momentum (OAM) induces the orbital and spinning motion of a trapped object depending on the spatial configuration. On the contrary, it is not clear whether circularly polarized light induces the orbital motion for the particles trapped off-axis. The present study reveals that the interparticle light-induced force due to the SAM enhances or weakens the orbital torque and modulates rotational dynamics depending on the number of NPs, where the rotation speed of NPs in the optical field with both positive SAM and OAM can be 4 times faster than that in the optical field with negative SAM and positive OAM. The obtained results will not only clarify the principle for the control of NPs based on OAM-SAM coupling via light-matter interaction but also contribute to the unconventional laser processing technique for nanostructures with various chiral symmetries.
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We have developed a novel bacterial detection technique by desiccating a bacterial suspension deposited on an electrode. It was also found that the use of an indium-tin-oxide (ITO) electrode dramatically improved the resolution of the voltammogram, allowing us to observe two pairs of redox peaks, each assigned to the adsorption of isoprenoid ubiquinone (UQn) and menaquinone (MKn), which were present in the bacterial cell envelopes, giving midpeak potentials of -0.015 and -0.25 V versus Ag|AgCl|saturated KCl| at pH 7.0, respectively. Most of the microorganisms classified in both the Gram-negative and -positive bacteria gave well-defined redox peaks, demonstrating that this procedure made the detection of the quinones possible without solvent extraction. It has been demonstrated that the present technique can be used not only for the detection of bacteria, but also for profiling of the isoprenoid quinones, which play important roles in electron and proton transfer in microorganisms. In this respect, the present technique provides a much more straightforward way than the solvent extraction in that one sample can be prepared in 1 min by heat evaporation of a suspension containing the targeted bacteria, which has been applied on the ITO electrode.
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Técnicas Eletroquímicas , Bactérias Gram-Positivas/química , Quinonas/análise , Eletrodos , Bactérias Gram-Negativas/química , Bactérias Gram-Negativas/metabolismo , Bactérias Gram-Positivas/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Oxirredução , Compostos de Estanho/química , Vitamina K 2/análiseRESUMO
In our study, various bacteria, including Gram-negative (Pseudomonas aeruginosa, Escherichia coli, Acinetobacter calcoaceticus, Serratia marcescens, Shewanella oneidensis) and Gram-positive (Bacillus subtilis) bacteria, were straightforwardly immobilized into the conducting polymers (CPs) by electrochemical deposition. The doping state of bacteria in the polymer films (polypyrrole and poly(3,4-ethylenedioxythiophene)) varied according to the polymerization conditions. The viability of bacteria in the polymers and of those adsorbed on various substrates was evaluated. The activity of bacteria doped on the polymer film was evaluated by cyclic voltammetry in a thin-layer cell.
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Bactérias Gram-Negativas/metabolismo , Bactérias Gram-Positivas/metabolismo , Polímeros/química , Pirróis/química , Compostos Bicíclicos Heterocíclicos com Pontes/química , Compostos Bicíclicos Heterocíclicos com Pontes/metabolismo , Técnicas Eletroquímicas , Bactérias Gram-Negativas/química , Bactérias Gram-Positivas/química , Polímeros/metabolismo , Pirróis/metabolismoRESUMO
Specific identification of bacteria has been achieved through precisely transferred bacterial structure on the surface of overoxidized polypyrrole (OPPy) film. The recognition of target bacteria was successfully carried out in real time using OPPy film in combination with dielectrophoresis. The unique combination of both techniques made the specific detection of template bacilli possible at concentrations as low as 10(3) CFU/mL within 3 min, without any bacterial pretreatment. The observation of the movement of bacteria by using a fluorescent microscope revealed that living bacteria were being trapped vertically in the cavity created in the OPPy film. Further, the bacterial cavities had high selectivity and were able to discriminate particular target bacteria, Pseudomonas aeruginosa, out of bacterial mixtures containing Acinetobacter calcoaceticus, Escherichia coli, and Serratia marcescens, which are known to have a similar shape. This simple method can be used for a wide variety of applications in which rapid bacterial detection is required, such as food safety risk assessment, clinical point-of-care testing, and continuous environmental monitoring.
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Eletroforese/métodos , Pseudomonas aeruginosa/química , Pseudomonas aeruginosa/isolamento & purificação , Eletroquímica , Impressão Molecular , Polímeros/síntese química , Polímeros/química , Pirróis/síntese química , Pirróis/químicaRESUMO
Extracellular vesicles (EVs), including nanoscale exosomes and ectosomes, hold promise as biomarkers that provide information about the cell of origin through their cargo of nucleic acids and proteins, both on their surface and within. Here, we develop a detection method of EVs based on light-induced acceleration of specific binding between their surface and antibody-modified microparticles, using a controlled microflow with three-dimensional analysis by confocal microscopy. Our method successfully detected 103-104 nanoscale EVs in liquid samples as small as a 500 nanoliters within 5 minutes, with the ability to distinguish multiple membrane proteins. Remarkably, we achieved the specific detection of EVs secreted from living cancer cell lines with high linearity, without the need for a time-consuming ultracentrifugation process that can take several hours. Furthermore, the detection range can be controlled by adjusting the action range of optical force using a defocused laser, consistent with the theoretical calculations. These findings demonstrate an ultrafast, sensitive, and quantitative approach for measuring biological nanoparticles, enabling innovative analyses of cell-to-cell communication and early diagnosis of various diseases, including cancer.
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Micropartículas Derivadas de Células , Exossomos , Vesículas Extracelulares , Neoplasias , Humanos , Micropartículas Derivadas de Células/metabolismo , Exossomos/metabolismo , Anticorpos/metabolismoRESUMO
The analysis of trace amounts of proteins based on immunoassays and other methods is essential for the early diagnosis of various diseases such as cancer, dementia, and microbial infections. Here, we propose a light-induced acceleration of antigen-antibody reaction of attogram-level proteins at the solid-liquid interface by tuning the laser irradiation area comparable to the microscale confinement geometry for enhancing the collisional probability of target molecules and probe particles with optical force and fluidic pressure. This principle was applied to achieve a 102-fold higher sensitivity and ultrafast specific detection in comparison with conventional protein detection methods (a few hours) by omitting any pretreatment procedures; 47-750 ag of target proteins were detected in 300 nL of sample after 3 minutes of laser irradiation. Our findings can promote the development of proteomics and innovative platforms for high-throughput bio-analyses under the control of a variety of biochemical reactions.
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Reações Antígeno-Anticorpo , Detecção Precoce de Câncer , Imunoensaio , ProteínasRESUMO
Rapid evaluation of functions in densely assembled bacteria is a crucial issue in the efficient study of symbiotic mechanisms. If the interaction between many living microbes can be controlled and accelerated via remote assembly, a cultivation process requiring a few days can be ommitted, thus leading to a reduction in the time needed to analyze the bacterial functions. Here, we show the rapid, damage-free, and extremely dense light-induced assembly of microbes over a submillimeter area with the "bubble-mimetic substrate (BMS)". In particular, we successfully assembled 104-105 cells of lactic acid bacteria (Lactobacillus casei), achieving a survival rate higher than 95% within a few minutes without cultivation process. This type of light-induced assembly on substrates like BMS, with the maintenance of the inherent functions of various biological samples, can pave the way for the development of innovative methods for rapid and highly efficient analysis of functions in a variety of microbes.
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Materiais Biomiméticos/química , Microbioma Gastrointestinal/efeitos da radiação , Intestinos/microbiologia , Lacticaseibacillus casei/efeitos da radiação , Lasers , Poliestirenos/química , Percepção de Quorum/efeitos da radiação , Viabilidade MicrobianaRESUMO
Some bacteria are recognized to produce useful substances and electric currents, offering a promising solution to environmental and energy problems. However, applications of high-performance microbial devices require a method to accumulate living bacteria into a higher-density condition in larger substrates. Here, we propose a method for the high-density assembly of bacteria (106 to 107 cells/cm2) with a high survival rate of 80 to 90% using laser-induced convection onto a self-organized honeycomb-like photothermal film. Furthermore, the electricity-producing bacteria can be optically assembled, and the electrical current can be increased by one to two orders of magnitude simply by increasing the number of laser irradiations. This concept can facilitate the development of high-density microbial energy conversion devices and provide new platforms for unconventional environmental technology.
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Bactérias/metabolismo , Luz , Fontes de Energia Bioelétrica , Polímeros/metabolismoRESUMO
A new strategy for the synthesis of a mushroom-like aggregate, based on repeated sequences of a 3D gold nanoparticle-conducting polymer-gold nanoparticle arrangement, by a single-step process at the organic/water interface has been described.
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Light-induced heating on a solid-liquid interface can generate a vapor submillimeter bubble and fluid flow, which enables us to densely and rapidly assemble dispersoids into a desired position (photothermal assembly). Here, we revealed that the surface modulation of the light-induced bubble by a surfactant dominates the assembly dynamics of nanoparticles and microparticles as dispersoids, which results in highly efficient photothermal assembly under the surfactant-controlled fluid flow. This mechanism can facilitate the concentration measurement of small objects (microparticles, bacteria, viruses, etc.). Particularly, we found that the surfactant-controlled fluid flow and bubble enable high-density assembly of dispersoids and remarkable enhancement of assembly efficiency, achieving 10-20 times in comparison with the case of no surfactant. This result can extend the limit of measurable concentration by one order. Furthermore, this study revealed the influence of concentration, size, and constituent material of the dispersoids on the assembly efficiency for the improvement of measurement precision. These findings are crucial for laser-induced assembly for the rapid concentration measurement of various microbes without a cultivation process as bioanalysis, for the high-sensitivity detection of harmful particles, and for the colloidal lithography.
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We focused on changes in the electrical property of the open bridge-structured gold nanoparticles array consisting of 46-nm parent and 12-nm son gold nanoparticles by hybridization and applied it for a simple electrical DNA detection. Since a target DNA of a 24-mer oligonucleotide was added to the probe DNA modified 12-nm Au nanoparticles, which was arranged on the gap between the 46-nm Au particles, the response was read by an electrical readout system. Even in a simple measuring method, we obtained a rapid response to the cDNA with a high S/N ratio of 30 over a wide concentration range and a detection limit of 5.0 fmol. Moreover, the array discriminated 1-base mismatches, regardless of their location in the DNA sequence, which enabled us to detect single-nucleotide polymorphism, which is one of the important diagnoses, without any polymerase chain reaction amplification, sophisticated instrumentation, or fluorescent labeling through an easy-to-handle electrical readout system.
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DNA/análise , DNA/química , Ouro/química , Nanopartículas Metálicas/química , Sequência de Bases , Nanopartículas Metálicas/ultraestrutura , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Técnicas de Sonda Molecular , Conformação de Ácido NucleicoRESUMO
Porphyrin-based molecules play an important role in natural biological systems such as photosynthetic antennae and haemoglobin. Recent organic chemistry provides artificial porphyrin-based molecules having unique electronic and optical properties, which leads to wide applications in material science. Here, we successfully produced many macroscopically anisotropic structures consisting of porphyrin dimers by light-induced solvothermal assembly with smooth evaporation in a confined volatile organic solvent. Light-induced fluid flow around a bubble on a gold nanofilm generated a sub-millimetre radial assembly of the tens-micrometre-sized petal-like structures. The optical properties of the petal-like structures depend on the relative angle between their growth direction and light polarisation, as confirmed by UV-visible extinction and the Raman scattering spectroscopy analyses, being dramatically different from those of structures obtained by natural drying. Thus, our findings pave the way to the production of structures and polycrystals with unique characteristics from various organic molecules.
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For sustainable human life, biosensing systems for contaminants or disease-causing bacteria are crucial for food security, environmental improvement, and disease prevention. With an aim of enhancing the sensitivity and detection speed, many researchers have developed efficient detection methods for target bacteria. In this review, we discuss recent topics related to active and passive bacterial detection methods, including (1) optical approaches with unique functional nano- and micro-structures, and (2) electrical approaches involving mechanical modulation and electrochemical reactions. Particularly, we discuss the prospects in the development of label-free, rapid, and highly sensitive biosensors based on active detection principles with light-induced dynamics, in conjunction with dielectrophoresis-induced selective trapping.
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Bactérias/isolamento & purificação , Técnicas Biossensoriais , Monitoramento Ambiental/métodos , Técnicas Eletroquímicas , NanotecnologiaRESUMO
Molecular imprinting technique enables the selective binding of nanoscale target molecules to a polymer film, within which their chemical structure is transcribed. Here, we report the successful production of mixed bacterial imprinted film (BIF) from several food poisoning bacteria by the simultaneous imprinting of their nanoscale surface chemical structures (SCS), and provide highly selective trapping of original micron-scale bacteria used in the production process of mixed BIF even for multiple kinds of bacteria in real samples. Particularly, we reveal the rapid specific identification of E. coli group serotypes (O157:H7 and O26:H11) using an alternating electric field and a quartz crystal microbalance. Furthermore, we have performed the detailed physicochemical analysis of the specific binding of SCS and molecular recognition sites (MRS) based on the dynamic Monte Carlo method under taking into account the electromagnetic interaction. The dielectrophoretic selective trapping greatly depends on change in SCS of bacteria damaged by thermal treatment, ultraviolet irradiation, or antibiotic drugs, which can be well explained by the simulation results. Our results open the avenue for an innovative means of specific and rapid detection of unknown bacteria for food safety and medicine from a nanoscale viewpoint.
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Aderência Bacteriana , Fenômenos Fisiológicos Bacterianos , Polímeros , Microbiologia de Alimentos/métodos , Viabilidade Microbiana , Impressão Molecular , Polímeros/química , Propriedades de SuperfícieRESUMO
We clarify an unconventional principle of the light-driven operation of a biosensor for enhanced sensitivity with the help of random nanospikes added to the surface of a nanohole array. Such a system is capable of optically guiding viruses and trapping them in the vicinity of a highly sensitive site by an anomalous light-induced force arising from random-nanospike-modulated extraordinary optical transmission and the plasmonic mirror image in a virus as a dielectric submicron object. In particular, after guiding the viruses near the apex of nanospikes, there are conditions where the spectral peak shift of extraordinary optical transmission can be greatly increased and reach several hundred nanometers in comparison with that of a conventional nanohole array without random nanospikes. These results will allow for the development of a simple, rapid, and highly sensitive virus detection method based on optical trapping with the help of random-nanospike-modulated extraordinary optical transmission, facilitating convenient medical diagnosis and food inspection.
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Macroscopic unique self-assembled structures are produced via double-stranded DNA formation (hybridization) as a specific binding essential in biological systems. However, a large amount of complementary DNA molecules are usually required to form an optically observable structure via natural hybridization, and the detection of small amounts of DNA less than femtomole requires complex and time-consuming procedures. Here, we demonstrate the laser-induced acceleration of hybridization between zeptomole-level DNA and DNA-modified nanoparticles (NPs), resulting in the assembly of a submillimetre network-like structure at the desired position with a dramatic spectral modulation within several minutes. The gradual enhancement of light-induced force and convection facilitated the two-dimensional network growth near the air-liquid interface with optical and fluidic symmetry breakdown. The simultaneous microscope observation and local spectroscopy revealed that the assembling process and spectral change are sensitive to the DNA sequence. Our findings establish innovative guiding principles for facile bottom-up production via various biomolecular recognition events.
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DNA/química , Nanopartículas/química , Conformação de Ácido Nucleico , Hibridização de Ácido Nucleico , Simulação por Computador , DNA/análise , Difusão , Ouro/química , Lasers , Luz , Nanopartículas Metálicas/química , Microscopia , Modelos Estatísticos , Análise de Sequência de DNARESUMO
To immobilize viable bacteria on an electrode, we present a novel and straightforward technique that relies on the negative ζ-potentials of bacteria for insertion into conducting polymers as dopants. In the present study, we conducted an electrochemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with various gram-negative bacteria, including Pseudomonas aeruginosa, Escherichia coli, and Shewanella oneidensis. The PEDOT film doped with bacteria indicated a typical redox response, high conductivity, and electrochemical stability. Fluorescence microscopy confirmed that approximately 90% of the bacteria incorporated into the PEDOT film at >0.5 µm in thickness were viable.