Plasmonic Nanobubbles Research Articles

Extraction evolutionary features of continuous light-induced plasmonic nanobubbles by a dynamic spectral regression model

A comprehensive understanding of the nature of light-induced plasmonic nanobubbles (PNBs) generated around noble metal nanoparticles is essential for optimizing PNB-based applications, such as light-driven microfluidic control. To investigate the overall evolution pattern of plasmonic nanobubbles (PNBs) under continuous light illumination, a computational model based on the least-squares method is established. Meanwhile, the variations in nanofluid transmittance and vaporization mass under continuous light illumination are measured by an immersion fiber and an electronic balance, respectively. The effects of nanoparticle concentration on the nanofluid transmittance and vaporization mass are analyzed. Considering the variations in nanofluid concentration, the overall evolution pattern of PNBs is preliminarily analyzed by monitoring the real-time dynamic change in nanofluid transmittance. The experimental results indicate that the nanoparticle concentration has an important effect on the nanofluid vaporization process. During the illumination stage, an increased nanofluid concentration intensifies the synergistic effect of water vaporization and PNB growth on transmittance reduction. The change in nanofluid transmittance caused by PNB scattering greatly exceeds that caused by increasing nanoparticle concentration. The nanofluid concentration gradually increases and peaks at the end of the cooling stage, and the rate of change of the nanofluid concentration is proportional to the nanofluid concentration. The numerical calculations show that the average size and the range of the PNB size distribution continuously increase with increasing irradiation time, and decrease during the cooling stage. A higher nanofluid concentration corresponds to a wider range of PNB size distribution.

Molecular Dynamics Simulation Combined with Near-Field Electromagnetic Analysis for Ultrashort-Pulsed Light-Induced Plasmonic Nanobubbles.

Ultrashort-pulsed light-induced nanobubbles gain great attention in research fields such as cancer therapy, optical imaging, and drug delivery. However, the mechanism governing the nucleation and growth of nanobubbles remains controversial. In this study, a molecular dynamics simulation combined with near-field electromagnetic theory is developed to investigate the influence of the localized surface plasmon resonance effect (LSPR) on nanobubble nucleation under various time-length pulsed light and to reveal the energy transfer differences during the nanobubble generation process. The results show that when silver nanoparticles (NPs) are irradiated by a 5 ps shorter-pulsed light, the temperature of the water layer adjacent to the nanoparticle surpasses that of the nanoparticle itself and reaches the spinodal temperature. This leads to nanobubbles' rapid nucleation at approximately 20 ps, which is 80 ps earlier than that irradiated by a 100 ps longer-pulsed light. Comparatively, during longer-pulsed light irradiation, a slower increase in both the temperature of the silver NPs and the water layer results in delayed nucleation of nanobubbles. Therefore, the plasmonic nanobubbles (PNBs) were observed around in 74 and 100 ps when irradiated by 50 and 100 ps longer-pulsed light, respectively. Moreover, the result indicates that the LSPR-induced enhanced electric field by shorter-pulsed light (5 ps) is 2.1 × 1010 V/m, which can accelerate the motion of water molecules surrounding silver NPs, resulting in rapid generation of nanobubbles. However, the intensities of the resonant electric field drop to 5.6 × 109 and 5.0 × 109 V/m when the duration times of pulsed light are 50 and 100 ps, respectively. These results indicate that the energy transfer mechanism of plasmonic nanobubbles (PNBs) under ultrashort-pulsed light irradiation might be very different from that of thermally mediated nanobubbles (TNBs). This work provides new insights into understanding the generation of PNBs induced by ultrashort-pulsed light.

Vapor Nanobubbles around Heated Nanoparticles: Wetting Dependence of the Local Fluid Thermodynamics and Kinetics of Nucleation.

Plasmonic nanobubbles are composite objects resulting from the interaction between light and metallic nanoparticles immersed in a fluid. Plasmonic nanobubbles have applications in photothermal therapies, drug delivery, microfluidic manipulations, and solar energy conversion. Their early formation is, however, barely characterized due to the short time and length scales relevant to the process. Here, we investigate, using molecular dynamics (MD) simulations, the effect of nanoparticle wettability on both the local fluid thermodynamics and the kinetics of nanobubble generation in water. We first show that the local onset temperature of vapor nucleation decreases with the nanoparticle/water interfacial energy and may be 100 K below the water spinodal temperature in the case of weak nanoparticle/water interactions. Second, we demonstrate that vapor nucleation may be slower in the case of weak water/nanoparticle interactions. This result, which is qualitatively at odds with the predictions of isothermal classical nucleation theory, may be explained by the competition between two antagonist effects: while, classically, hydrophobicity increases the vapor nucleation rate, it also penalizes interfacial thermal transfer, slowing down kinetics. The kinetics of heat transfer from the nanoparticle to water is controlled by the interfacial thermal conductance. This quantity turns out not only to decrease with the nanoparticle hydrophobicity but also drops down prior to phase change, yielding even longer nucleation times. Such conclusions were reached by considering the comparison between MD and continuous heat transfer models. These results put forward the role of nanoparticle wettability in the generation of plasmonic nanobubbles observed experimentally and open the path to the control of boiling using nanopatterned surfaces.

The non-linear evolution of radiative properties of plasmonic nanofluid during light-induced vaporization process

The light-induced vaporization process of plasmonic nanofluid plays an essential role in solar energy harvesting. Under light illumination, metallic nanoparticles can be converted into ideal thermal sources at nanoscale and generate plasmonic nanobubbles (PNBs) at the localized surface plasmon resonance (LSPR) wavelength, Therefore, the radiative properties of nanofluid closely correlate with the evolution of PNB nucleation, growth, fusion, and dissipation. A model based on finite element modeling is developed to investigate the evolution of radiative properties. The effect of gold nanoparticle (AuNP) size, PNB size, and AuNP aggregation morphology on the extinction cross section, albedo, and LSPR peak wavelength of particle-bubble complexes (P-B complexes) during the evolution of PNB is determined. The results indicate that with the vaporization process of nanofluid, the evolution of PNBs makes the radiation properties exhibit an obvious non-linear evolution pattern. Specifically, the generation of PNB shifts the LSPR peak wavelength towards blue, while the aggregation of AuNPs shifts it towards red. In the presence of PNB, the variation of the LSPR peak wavelength depends on the competition between the blue-shifting effect of PNB growth and the red-shifting effect of AuNP aggregation. After PNB dissipation, the aggregation of AuNPs raises the aggregates’ albedo. An albedo lower than 0.5 indicates a strong absorption of incident light energy. The increase in AuNP size, PNB size, and the aggregation of AuNPs all contribute to the increase in the peak extinction cross section. When PNB is present, whether the albedo of P-B complexes exceeds 0.5 depends on the relative magnitude of the extinction cross section of AuNP aggregates and PNB. The increase in the number of AuNPs aggregation layers causes the blue-shifted LSPR peak wavelength of AuNP aggregates, the decreased peak extinction cross section, the increased LSPR peak width, and the potential for multiple extinction peaks.

Microfluidic device-fabricated spiky nano-burflower shape gold nanomaterials facilitate large biomolecule delivery into cells using infrared light pulses.

Photothermal nanoparticle-sensitised photoporation is an emerging approach, which is considered an efficient tool for the intracellular delivery of biomolecules. Nevertheless, using this method to achieve high transfection efficiency generally compromises cell viability and uneven distribution of nanoparticles results in non-uniform delivery. Here, we show that high aspect ratio gold nano-burflowers, synthesised in a microfluidic device, facilitate highly efficient small to very-large cargo delivery uniformly using infrared light pulses without sacrificing cell viability. By precisely controlling the flow rates of shaping reagent and reducing agent, high-density (24 numbers) sharply branched spikes (∼80 nm tip-to-tip length) of higher aspect ratios (∼6.5) with a small core diameter (∼45 nm) were synthesised. As produced gold burflower-shape nanoparticles are biocompatible, colloidally stable (large surface zeta potential value), and uniform in morphology with a higher plasmonic peak (max. 890 nm). Theoretical analysis revealed that spikes on the nanoparticles generate a higher electromagnetic field enhancement upon interaction with light pulses. It induces plasmonic nanobubbles in the vicinity of the cells, followed by pore formation on the membrane leading to diverse biomolecular delivery into cells. Our platform has been successfully implemented for uniform delivery of small to very large biomolecules, including siRNA (20-24 bp), plasmid DNA expressing green fluorescent protein (6.2 kbp), Cas-9 plasmid (9.3 kbp), and β-galactosidase enzyme (465 kDa) into diverse mammalian cells with high transfection efficiency and cell viability. For very large biomolecules such as enzymes, the best results were achieved as ∼100% transfection efficiency and ∼100% cell viability in SiHa cells. Together, our findings demonstrate that the spiky gold nano-burflower shape nanoparticles manufactured in a microfluidic system exhibited excellent plasmonic behaviour and could serve as an effective tool in manipulating cell physiology.

Laser-Induced Plasmonic Nanobubbles and Microbubbles in Gold Nanorod Colloidal Solution.

In this work, we studied the initiated plasmonic nanobubbles and the follow-up microbubble in gold nanorod (GNR) colloidal solution induced by a pulsed laser. Owing to the surface plasmon resonance (SPR)-enhanced photothermal effect of GNR, several nanobubbles are initiated at the beginning of illumination and then to trigger the optical breakdown of water at the focal spot of a laser beam. Consequently, microbubble generation is facilitated; the threshold of pulsed laser energy is significantly reduced for the generation of microbubbles in water with the aid of GNRs. We used a probing He-Ne laser with a photodetector and an ultrasonic transducer to measure and investigate the dynamic formations of nanobubbles and the follow-up microbubble in GNR colloids. Two wavelengths (700 nm and 980 nm) of pulsed laser beams are used to irradiate two kinds of dilute GNR colloids with different longitudinal SPRs (718 nm and 966 nm). By characterizing the optical and photoacoustic signals, three types of microbubbles are identified: a single microbubble, a coalesced microbubble of multiple microbubbles, and a splitting microbubble. The former is caused by a single breakdown, whereas the latter two are caused by discrete and series-connected multiple breakdowns, respectively. We found that the thresholds of pulsed energy to induce different types of microbubbles are reduced as the concentration of GNRs increases, particularly when the wavelength of the laser is in the near-infrared (NIR) region and close to the SPR of GNRs. This advantage of a dilute GNR colloid facilitating the laser-induced microbubble in the NIR range of the bio-optical window could make biomedical applications available. Our study may provide an insight into the relationship between plasmonic nanobubbles and the triggered microbubbles.

Digital plasmonic nanobubble detection for rapid and ultrasensitive virus diagnostics

Rapid and sensitive diagnostics of infectious diseases is an urgent and unmet need as evidenced by the COVID-19 pandemic. Here, we report a strategy, based on DIgitAl plasMONic nanobubble Detection (DIAMOND), to address this need. Plasmonic nanobubbles are transient vapor bubbles generated by laser heating of plasmonic nanoparticles (NPs) and allow single-NP detection. Using gold NPs as labels and an optofluidic setup, we demonstrate that DIAMOND achieves compartment-free digital counting and works on homogeneous immunoassays without separation and amplification steps. DIAMOND allows specific detection of respiratory syncytial virus spiked in nasal swab samples and achieves a detection limit of ~100 PFU/mL (equivalent to 1 RNA copy/µL), which is competitive with digital isothermal amplification for virus detection. Therefore, DIAMOND has the advantages including one-step and single-NP detection, direct sensing of intact viruses at room temperature, and no complex liquid handling, and is a platform technology for rapid and ultrasensitive diagnostics.

Plasmonic Nanobubbles–A Perspective

The field of plasmonic nanobubbles, referring to bubbles generated around nanoparticles due to plasmonic heating, is growing rapidly in recent years. Theoretical, simulation and experimental studies have been reported to reveal the fundamental physics related to this nanoscale multi-physics phenomenon. Using plasmonic nanobubbles for applications is in the early stage but progressing. In this article, we briefly review the current state of this research field and give our perspectives on the research needs in the theoretical, simulation and experimental fronts. We also give our perspectives on how the fundamental understanding can be applied to more practical applications.

Strong and fast rising pressure waves emitted by plasmonic vapor nanobubbles

Plasmonic vapor nanobubbles are currently considered for a wide variety of applications ranging from solar energy harvesting and photoacoustic imaging to nanoparticle-assisted cancer therapy. Yet, due to their small size and unstable nature, their generation and consequences remain difficult to characterize. Here, building on a phase-field model, we report on the existence of strong pressure waves that are emitted when vapor nanobubbles first form around a laser-heated nanoparticle immersed in water and subsequently after bubble rebound. These effects are strongest when the fluid is locally brought high in its supercritical state, which may be realized with a short laser pulse. Because of the greatly out-of-equilibrium nature of nanobubble generation, the waves combine a high-pressure peak with a fast pressure rising time and propagate in water over micron distances, opening the way to induce spatially and temporally localized damage. Discussing the consequences on biological cell membranes, we conclude that acoustic-mediated perforation is more efficient than nanobubble expansion to breach the membrane. Our findings should serve as a guide for optimizing the thermoacoustic conversion efficiency of plasmonic vapor nanobubbles.4 MoreReceived 10 December 2020Accepted 13 May 2021DOI:https://doi.org/10.1103/PhysRevResearch.3.023231Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCavitationDrops & bubblesThermoacoustic effectCondensed Matter & Materials PhysicsFluid Dynamics

Radiation induced plasmonic nanobubbles: fundamentals, applications and prospects

<abstract> When plasmonic nanoparticles (PNPs) are illuminated by a light source with a plasmon frequency, an intensive localized surface plasmon resonance (LSPR) effect can be excited, which causes an obvious enhancement of the local electric field around the PNPs. The light energy is converted into heat by the PNPs, causing a gradual increase in the temperature of the media around these PNPs. Under the induction of radiation, the heat generated by PNPs vaporizes the surrounding water, and under the combined effect of the local electric field, plasmonic nanobubbles (PNBs) are generated. After that, PNBs will continue to grow, which is mainly caused by the influx of dissolved gas from the surrounding water. With the growth of PNBs, PNB-induced micro convection and some unique nonlinear changes of optical properties can be observed. Since the size, location and lifetime of PNBs can be flexibly controlled by adjusting the parameters of the light source, PNBs have been widely used in several emerging applications such as microfluidic manipulations, medical drug delivery and cell therapy. In this review, we first introduce the physical mechanism of PNB generation and discuss the micro convection and optical nonlinearity caused by PNBs. In addition, we demonstrate the nucleation mechanism and the growth kinetics of PNBs. Then we review the PNBs-based applications in microfluid flow control, particle manipulation, optical property tuning, medical drug delivery and cancer therapy. Finally, we summarize the current challenges of this field and propose an outlook for future developments. </abstract>

Plasmonic Nanobubbles in “Armored” Surface Nanodroplets

Plasmonic nanobubbles are bubbles that are formed from local heat generated by noble metal nanoparticles under illumination of light at resonance. Understanding the formation and behavior of plasmo...

Explosive, oscillatory, and Leidenfrost boiling at the nanoscale.

We investigate the different boiling regimes around a single continuously laser-heated 80nm gold nanoparticle and draw parallels to the classical picture of boiling. Initially, nanoscale boiling takes the form of transient, inertia-driven, unsustainable boiling events characteristic of a nanoscale boiling crisis. At higher heating power, nanoscale boiling is continuous, with a vapor film being sustained during heating for at least up to 20μs. Only at high heating powers does a substantial stable vapor nanobubble form. At intermediate heating powers, unstable boiling sometimes takes the form of remarkably stable nanobubble oscillations with frequencies between 40MHz and 60MHz, frequencies that are consistent with the relevant size scales according to the Rayleigh-Plesset model of bubble oscillation, though how applicable that model is to plasmonic vapor nanobubbles is not clear.

Retraction: Improved Cellular Specificity of Plasmonic Nanobubbles versus Nanoparticles in Heterogeneous Cell Systems.

Retraction: Improved Cellular Specificity of Plasmonic Nanobubbles versus Nanoparticles in Heterogeneous Cell Systems.

Retraction of "Transient Photothermal Spectra of Plasmonic Nanobubbles".

The photothermal efficacy of near-infrared gold nanoparticles (NP), nanoshells, and nanorods was studied under pulsed high-energy optical excitation in plasmonic nanobubble (PNB) mode as a function of the wavelength and duration of the excitation laser pulse. PNBs, transient vapor nanobubbles, were generated around individual and clustered overheated NPs in water and living cells. Transient PNBs showed two photothermal features not previously observed for NPs: the narrowing of the spectral peaks to 1 nm and the strong dependence of the photothermal efficacy upon the duration of the laser pulse. Narrow red-shifted (relative to those of NPs) near-infrared spectral peaks were observed for 70 ps excitation laser pulses, while longer sub- and nanosecond pulses completely suppressed near-infrared peaks and blue shifted the PNB generation to the visual range. Thus, PNBs can provide superior spectral selectivity over gold NPs under specific optical excitation conditions.

Plasmonic Nanosurgery for Destruction of Microscopic Residual Disease Following Resection in Cancer

Surgery, when possible, continues to remain the best possible treatment option for cancer patients. However, in some cases the cancer can be unresectable and requires radiation or chemotherapy prior to surgery even being an option. Macroscopic surgery can leave behind microscopic residual disease, which can lead to recurrence and may be lethal. Image-guided surgery has shown clinical benefit by reducing recurrence rates and improving survival in patients. Remotely triggered destruction of microscopic residual disease immediately following macroscopic resection would be an attractive tool for surgeons and a beneficial option for patients. Externally activated, targeted destruction of cancer could also be used for the management of unresectable tumors. Here, we explore the use of biocompatible, gold nanoparticles for photo-triggered destruction of microscopic residual disease through the formation of plasmonic nanobubbles. A pulsed laser is used to activate gold nanoparticles, which through surface plasmon resonance causes a rise in temperature that in turn vaporizes nearby liquid medium to form short-lived nanobubbles, which are referred to as plasmonic nanobubbles. When these nanobubbles form and then collapse, a pressure pulse is emitted only in cancerous cells that can be photo acoustically detected and this signal can be converted into an image. These nanobubbles can be used either for nano-guided surgery or nanosurgery in which the pressure pulse emitted actually destroys the cancer cells. These plasmonic nanobubbles have been extensively explored by Lukianova-Hleb and co-workers for cancer applications. Their animal studies showed that following surgery, they could detect the remaining tumor cells at a tissue depth of 4mm, which is highly significant for the clinical translation of this technology. The high selectivity of plasmonic nanobubbles, along with the ability for real-time elimination of microscopic residual disease demonstrated by these researchers could form the basis for a clinical trial and the eventual clinical translation of nanosurgery for cancer applications.

Vapor Bubbles

This article reviews the fundamental physics of vapor bubbles in liquids. Work on bubble growth and condensation for stationary and translating bubbles is summarized and the differences with bubbles containing a permanent gas stressed. In particular, it is shown that the natural frequency of a vapor bubble is proportional not to the inverse radius, as for a gas bubble, but to the inverse radius raised to the power 2/3. Permanent gas dissolved in the liquid diffuses into the bubble with strong effects on its dynamics. The effects of the diffusion of heat and mass on the propagation of pressure waves in a vaporous bubbly liquid are discussed. Other topics briefly touched on include thermocapillary flow, plasmonic nanobubbles, and vapor bubbles in an immiscible liquid.

Methods for Generation and Detection of Nonstationary Vapor Nanobubbles Around Plasmonic Nanoparticles.

Laser pulse-induced vapor nanobubbles are nonstationary nanoevents that offer a broad range of applications, especially in the biomedical field. Plasmonic (usually gold) nanoparticles have the highest energy efficacy of the generation of vapor nanobubbles and such nanobubbles were historically named as plasmonic nanobubbles. Below we review methods (protocols) for generating and detecting plasmonic nanobubbles in liquids. The biomedical applications of plasmonic nanobubbles include in vivo and in vitro detection and imaging, gene transfer, micro-surgery, drug delivery, and other diagnostic, therapeutic, and theranostic applications.

Retraction of "Tunable Plasmonic Nanoprobes for Theranostics of Prostate Cancer".

[This retracts the article on p. 3 in vol. 1, PMID: 21547151.].

Remotely Triggered Nano-Theranostics For Cancer Applications.

Nanotechnology has enabled the development of smart theranostic platforms that can concurrently diagnose disease, start primary treatment, monitor response, and, if required, initiate secondary treatments. Recent in vivo experiments demonstrate the promise of using theranostics in the clinic. In this paper, we review the use of remotely triggered theranostic nanoparticles for cancer applications, focusing heavily on advances in the past five years. Remote triggering mechanisms covered include photodynamic, photothermal, phototriggered chemotherapeutic release, ultrasound, electro-thermal, magneto-thermal, X-ray, and radiofrequency therapies. Each section includes a brief overview of the triggering mechanism and summarizes the variety of nanoparticles employed in each method. Emphasis in each category is placed on nano-theranostics with in vivo success. Some of the nanotheranostic platforms highlighted include photoactivatable multi-inhibitor nanoliposomes, plasmonic nanobubbles, reduced graphene oxide-iron oxide nanoparticles, photoswitching nanoparticles, multispectral optoacoustic tomography using indocyanine green, low temperature sensitive liposomes, and receptor-targeted iron oxide nanoparticles loaded with gemcitabine. The studies reviewed here provide strong evidence that the field of nanotheranostics is rapidly evolving. Such nanoplatforms may soon enable unique advances in the clinical management of cancer. However, reproducibility in the synthesis procedures of such “smart” platforms that lend themselves to easy scale-up in their manufacturing, as well as the development of new and improved models of cancer that are more predictive of human responses, need to happen soon for this field to make a rapid clinical impact.

A Study on Multipeutics

Multipeutics is the simultaneous application of m ≥ 4 cancer treatments. m = 4 is quadrapeutics, which was invented by researchers at Rice University, Northeastern University, MD Anderson Cancer Centre and China Medical University, see [1]. Multipeutics is our idea. From section 6 Summary, it follows that multipeutics can be more potent than quadrapeutics by comparing these two mathematical models. The first two treatments in quadrapeutics are systemically administered nano gold particles G and lysosomal chemo therapeutic drug D. They form mixed clusters M primarily in cancer cells and can be excited by a laser pulse, the third treatment, to form plasmonic nanobubbles N. These nanobubbles can kill the cancer cells by mechanical impact. If they do not the chemo therapeutic drug can be released into the cytoplasm, which might be lethal to the cancer cell. The fourth treatment is x rays X and the cancer cells have been sensitized to x rays by the treatment. We present an ODE (ordinary differential equations) model of quadrapeutics and of multipeutics, which is quadrapeutics and n ≥ 1 immune or chemo therapies. In the present paper we have found a polynomial p of degree at most 2(n + 3), such that a singular point (C, D, G, M, N, I1, …, In) will have p(M) = 0 Here I1, …, In are immune or chemo therapies. So this gives us candidates for singular points. Quadrapeutics is treated extensively. We find in theorem 3 a polynomium s of degree at most six in M such that a positive singular point (C, D, G, M, N) of the quadrapeutics system will have s(M) = 0. The main theorem of the present paper is the multipeutics theorem, saying that the more treatments we apply the lower the cancer burden, even if we take the doses of each treatment smaller. From the proof of this theorem, we can say, that quadrapeutics can outperform chemo radiation if the nanobubble kill rate k21 is sufficiently big. See also Figure 1 and Figure 2 and the text explaining them.