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1.
Small ; 17(42): e2103505, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34554636

RESUMO

The implementation of in vivo fluorescence imaging as a reliable diagnostic imaging modality at the clinical level is still far from reality. Plenty of work remains ahead to provide medical practitioners with solid proof of the potential advantages of this imaging technique. To do so, one of the key objectives is to better the optical performance of dedicated contrast agents, thus improving the resolution and penetration depth achievable. This direction is followed here and the use of a novel AgInSe2 nanoparticle-based contrast agent (nanocapsule) is reported for fluorescence imaging. The use of an Ag2 Se seeds-mediated synthesis method allows stabilizing an uncommon orthorhombic crystal structure, which endows the material with emission in the second biological window (1000-1400 nm), where deeper penetration in tissues is achieved. The nanocapsules, obtained via phospholipid-assisted encapsulation of the AgInSe2 nanoparticles, comply with the mandatory requisites for an imaging contrast agent-colloidal stability and negligible toxicity-and show superior brightness compared with widely used Ag2 S nanoparticles. Imaging experiments point to the great potential of the novel AgInSe2 -based nanocapsules for high-resolution, whole-body in vivo imaging. Their extended permanence time within blood vessels make them especially suitable for prolonged imaging of the cardiovascular system.


Assuntos
Nanocápsulas , Nanopartículas , Pontos Quânticos , Diagnóstico por Imagem , Fluorescência , Imagem Óptica
2.
Nano Lett ; 18(1): 602-609, 2018 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-29206471

RESUMO

The reduced magnitude of the optical trapping forces exerted over sub-200 nm dielectric nanoparticles complicates their optical manipulation, hindering the development of techniques and studies based on it. Improvement of trapping capabilities for such tiny objects requires a deep understanding of the mechanisms beneath them. Traditionally, the optical forces acting on dielectric nanoparticles have been only correlated with their volume, and the size has been traditionally identified as a key parameter. However, the most recently published research results have shown that the electrostatic characteristics of a sub-100 nm dielectric particle could also play a significant role. Indeed, at present it is not clear what optical forces depend. In this work, we designed a set of experiments in order to elucidate the different mechanism and properties (i.e., size and/or electrostatic properties) that governs the magnitude of optical forces. The comparison between experimental data and numerical simulations have shown that the double layer induced at nanoparticle's surface, not considered in the classical description of nanoparticle's polarizability, plays a relevant role determining the magnitude of the optical forces. Here, the presented results constitute the first step toward the development of the dielectric nanoparticle over which enhanced optical forces could be exerted, enabling their optical manipulation for multiples purposes ranging from fundamental to applied studies.

3.
Nano Lett ; 16(12): 8005-8014, 2016 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-27960460

RESUMO

Precise knowledge and control over the orientation of individual upconverting particles is extremely important for full exploiting their capabilities as multifunctional bioprobes for interdisciplinary applications. In this work, we report on how time-resolved, single particle polarized spectroscopy can be used to determine the orientation dynamics of a single upconverting particle when entering into an optical trap. Experimental results have unequivocally evidenced the existence of a unique stable configuration. Numerical simulations and simple numerical calculations have demonstrated that the dipole magnetic interactions between the upconverting particle and trapping radiation are the main mechanisms responsible of the optical torques that drive the upconverting particle to its stable orientation. Finally, how a proper analysis of the rotation dynamics of a single upconverting particle within an optical trap can provide valuable information about the properties of the medium in which it is suspended is demonstrated. A proof of concept is given in which the laser driven intracellular rotation of upconverting particles is used to successfully determine the intracellular dynamic viscosity by a passive and an active method.

4.
Small ; 11(13): 1555-61, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25451550

RESUMO

3D remote control of multifunctional fluorescent up-converting nanoparticles (UCNPs) using optical forces is being required for a great variety of applications including single-particle spectroscopy, single-particle intracellular sensing, controlled and selective light-activated drug delivery and light control at the nanoscale. Most of these potential applications find a serious limitation in the reduced value of optical forces (tens of fN) acting on these nanoparticles, due to their reduced dimensions (typically around 10 nm). In this work, this limitation is faced and it is demonstrated that the magnitude of optical forces acting on UCNPs can be enhanced by more than one order of magnitude by a controlled modification of the particle/medium interface. In particular, substitution of cationic species at the surface by other species with higher mobility could lead to UCNPs trapping with constants comparable to those of spherical metallic nanoparticles.


Assuntos
Nanopartículas , Óptica e Fotônica , Fluorescência , Microscopia Eletrônica de Transmissão , Propriedades de Superfície
5.
Small ; 9(12): 2162-70, 2013 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-23401166

RESUMO

Laser-induced thermal effects in optically trapped microspheres and single cells are investigated by quantum dot luminescence thermometry. Thermal spectroscopy has revealed a non-localized temperature distribution around the trap that extends over tens of micrometers, in agreement with previous theoretical models besides identifying water absorption as the most important heating source. The experimental results of thermal loading at a variety of wavelengths reveal that an optimum trapping wavelength exists for biological applications close to 820 nm. This is corroborated by a simultaneous analysis of the spectral dependence of cellular heating and damage in human lymphocytes during optical trapping. This quantum dot luminescence thermometry demonstrates that optical trapping with 820 nm laser radiation produces minimum intracellular heating, well below the cytotoxic level (43 °C), thus, avoiding cell damage.

6.
Adv Mater ; 35(52): e2306606, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37787978

RESUMO

Luminescence lifetime-based sensing is ideally suited to monitor biological systems due to its minimal invasiveness and remote working principle. Yet, its applicability is limited in conditions of low signal-to-noise ratio (SNR) induced by, e.g., short exposure times and presence of opaque tissues. Herein this limitation is overcome by applying a U-shaped convolutional neural network (U-NET) to improve luminescence lifetime estimation under conditions of extremely low SNR. Specifically, the prowess of the U-NET is showcased in the context of luminescence lifetime thermometry, achieving more precise thermal readouts using Ag2 S nanothermometers. Compared to traditional analysis methods of decay curve fitting and integration, the U-NET can extract average lifetimes more precisely and consistently regardless of the SNR value. The improvement achieved in the sensing performance using the U-NET is demonstrated with two experiments characterized by extreme measurement conditions: thermal monitoring of free-falling droplets, and monitoring of thermal transients in suspended droplets through an opaque medium. These results broaden the applicability of luminescence lifetime-based sensing in fields including in vivo experimentation and microfluidics, while, hopefully, spurring further research on the implementation of machine learning (ML) in luminescence sensing.


Assuntos
Luminescência , Termometria , Redes Neurais de Computação
7.
Front Chem ; 10: 941861, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35903194

RESUMO

Minimally invasive monitoring of brain activity is essential not only to gain understanding on the working principles of the brain, but also for the development of new diagnostic tools. In this perspective we describe how brain thermometry could be an alternative to conventional methods (e.g., magnetic resonance or nuclear medicine) for the acquisition of thermal images of the brain with enough spatial and temperature resolution to track brain activity in minimally perturbed animals. We focus on the latest advances in transcranial luminescence thermometry introducing a critical discussion on its advantages and shortcomings. We also anticipate the main challenges that the application of luminescent nanoparticles for brain thermometry will face in next years. With this work we aim to promote the development of near infrared luminescence for brain activity monitoring, which could also benefit other research areas dealing with the brain and its illnesses.

8.
Nanoscale Adv ; 3(22): 6310-6329, 2021 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-36133487

RESUMO

Research in novel materials has been extremely active over the past few decades, wherein a major area of interest has been nanoparticles with special optical properties. These structures can overcome some of the intrinsic limitations of contrast agents routinely used in medical practice, while offering additional functionalities. Materials that absorb or scatter near infrared light, to which biological tissues are partially transparent, have attracted significant attention and demonstrated their potential in preclinical research. In this review, we provide an at-a-glance overview of the most recent developments in near infrared nanoparticles that could have far-reaching applications in the life sciences. We focus on materials that offer additional functionalities besides diagnosis based on optical contrast: multiple imaging modalities (multimodal imaging), sensing of physical and chemical cues (multivariate diagnosis), or therapeutic activity (theranostics). Besides presenting relevant case studies for each class of optically active materials, we discuss their design and safety considerations, detailing the potential hurdles that may complicate their clinical translation. While multifunctional nanomaterials have shown promise in preclinical research, the field is still in its infancy; there is plenty of room to maximize its impact in preclinical studies as well as to deliver it to the clinics.

9.
Adv Mater ; 33(30): e2100077, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34117667

RESUMO

Deliberate and local increase of the temperature within solid tumors represents an effective therapeutic approach. Thermal therapies embrace this concept leveraging the capability of some species to convert the absorbed energy into heat. To that end, magnetic hyperthermia (MHT) uses magnetic nanoparticles (MNPs) that can effectively dissipate the energy absorbed under alternating magnetic fields. However, MNPs fail to provide real-time thermal feedback with the risk of unwanted overheating and impeding on-the-fly adjustment of the therapeutic parameters. Localization of MNPs within a tissue in an accurate, rapid, and cost-effective way represents another challenge for increasing the efficacy of MHT. In this work, MNPs are combined with state-of-the-art infrared luminescent nanothermometers (LNTh; Ag2 S nanoparticles) in a nanocapsule that simultaneously overcomes these limitations. The novel optomagnetic nanocapsule acts as multimodal contrast agents for different imaging techniques (magnetic resonance, photoacoustic and near-infrared fluorescence imaging, optical and X-ray computed tomography). Most crucially, these nanocapsules provide accurate (0.2 °C resolution) and real-time subcutaneous thermal feedback during in vivo MHT, also enabling the attainment of thermal maps of the area of interest. These findings are a milestone on the road toward controlled magnetothermal therapies with minimal side effects.


Assuntos
Meios de Contraste/química , Nanopartículas Magnéticas de Óxido de Ferro/química , Nanocápsulas/química , Animais , Linhagem Celular Tumoral , Corantes Fluorescentes/química , Temperatura Alta , Humanos , Hipertermia Induzida , Raios Infravermelhos , Campos Magnéticos , Magnetismo , Camundongos , Imagem Óptica , Terapia Fototérmica , Compostos de Prata/química
10.
Front Chem ; 8: 593398, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33240853

RESUMO

Since Ashkin's pioneering work, optical tweezers have become an essential tool to immobilize and manipulate microscale and nanoscale objects. The use of optical tweezers is key for a variety of applications, including single-molecule spectroscopy, colloidal dynamics, tailored particle assembly, protein isolation, high-resolution surface studies, controlled investigation of biological processes, and surface-enhanced spectroscopy. In recent years, optical trapping of individual sub-100-nm objects has got the attention of the scientific community. In particular, the three-dimensional manipulation of single lanthanide-doped luminescent nanoparticles is of great interest due to the sensitivity of their luminescent properties to environmental conditions. Nevertheless, it is really challenging to trap and manipulate single lanthanide-doped nanoparticles due to the weak optical forces achieved with conventional optical trapping strategies. This limitation is caused, firstly, by the diffraction limit in the focusing of the trapping light and, secondly, by the Brownian motion of the trapped object. In this work, we summarize recent experimental approaches to increase the optical forces in the manipulation of lanthanide-doped nanoparticles, focusing our attention on their surface modification and providing a critical review of the state of the art and future prospects.

11.
Adv Biosyst ; 3(10): e1900082, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-32648719

RESUMO

Chemicals capable of producing structural and chemical changes on cells are used to treat diseases (e.g., cancer). Further development and optimization of chemotherapies require thorough knowledge of the effect of the chemical on the cellular structure and dynamics. This involves studying, in a noninvasive way, the properties of individual cells after drug administration. Intracellular viscosity is affected by chemical treatments and it can be reliably used to monitor chemotherapies at the cellular level. Here, cancer cell monitoring during chemotherapeutic treatments is demonstrated using intracellular allocated upconverting nanorockers. A simple analysis of the polarized visible emission of a single particle provides a real-time readout of its rocking dynamics that are directly correlated to the cytoplasmic viscosity. Numerical simulations and immunodetection are used to correlate the measured intracellular viscosity alterations to the changes produced in the cytoskeleton of cancer cells by anticancer drugs (colchicine and Taxol). This study evidences the possibility of monitoring cellular properties under an external chemical stimulus for the study and development of new treatments. Moreover, it provides the biomedical community with new tools to study intracellular dynamics and cell functioning.


Assuntos
Antineoplásicos , Citoplasma/efeitos dos fármacos , Monitoramento de Medicamentos/métodos , Nanoestruturas , Viscosidade/efeitos dos fármacos , Antineoplásicos/química , Antineoplásicos/farmacologia , Citoesqueleto/efeitos dos fármacos , Células HeLa , Humanos , Microscopia de Fluorescência , Nanoestruturas/química
12.
Nanoscale ; 10(27): 12935-12956, 2018 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-29953157

RESUMO

The current status of the use of core-shell rare-earth-doped nanoparticles in biomedical applications is reviewed in detail. The different core-shell rare-earth-doped nanoparticles developed so far are described and the most relevant examples of their application in imaging, sensing, and therapy are summarized. In addition, the advantages and disadvantages they present are discussed. Finally, a critical opinion of their potential application in real life biomedicine is given.


Assuntos
Metais Terras Raras , Nanopartículas , Pesquisa Biomédica
13.
Adv Mater ; 28(12): 2421-6, 2016 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-26821941

RESUMO

3D optical manipulation of a thermal-sensing upconverting particle allows for the determination of the extension of the thermal gradient created in the surroundings of a plasmonic-mediated photothermal-treated HeLa cancer cell.


Assuntos
Nanopartículas/química , Európio/química , Fluoretos/química , Ouro/química , Células HeLa , Humanos , Lasers , Microscopia Eletrônica de Varredura , Microscopia de Fluorescência , Nanopartículas/metabolismo , Nanotubos/química , Temperatura , Itérbio/química , Ítrio/química
14.
Nanoscale ; 8(1): 300-8, 2016 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-26607763

RESUMO

An approach to unequivocally determine the three-dimensional orientation of optically manipulated NaYF4:Er(3+),Yb(3+) upconverting nanorods (UCNRs) is demonstrated. Long-term immobilization of individual UCNRs inside single and multiple resonant optical traps allow for stable single UCNR spectroscopy studies. Based on the strong polarization dependent upconverted luminescence of UCNRs it is possible to unequivocally determine, in real time, their three-dimensional orientation when optically trapped. In single-beam traps, polarized single particle spectroscopy has concluded that UCNRs orientate parallel to the propagation axis of the trapping beam. On the other hand, when multiple-beam optical tweezers are used, single particle polarization spectroscopy demonstrated how full spatial control over UCNR orientation can be achieved by changing the trap-to-trap distance as well as the relative orientation between optical traps. All these results show the possibility of real time three-dimensional manipulation and tracking of anisotropic nanoparticles with wide potential application in modern nanobiophotonics.

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