Bismuth selenide nanostructured clusters as optical coherence tomography contrast agents: beyond gold-based particles

Optical coherence tomography (OCT) is an imaging technique currently used in clinical practice to obtain optical biopsies of different biological tissues in a minimally invasive way. Among the contrast agents proposed to increase the efficacy of this imaging method, gold nanoshells (GNSs) are the best performing ones. However, their preparation is generally time-consuming, and they are intrinsically costly to produce. Herein, we propose a more affordable alternative to these contrast agents: Bi2Se3 nanostructured clusters with a desert rose-like morphology prepared via a microwave-assisted method. The structures are prepared in a matter of minutes, feature strong near-infrared extinction properties, and are biocompatible. They also boast a photon-to-heat conversion efficiency of close to 50%, making them good candidates as photothermal therapy agents. In vitro studies evidence the prowess of Bi2Se3 clusters as OCT contrast agents and prove that their performance is comparable to that of GNSsJ.Y. acknowledges the support from the China Scholarship Council (CSC file no. 201704910867). R.M. acknowledges the support of the European Commission through the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant agreement no. 797945 (LANTERNS). This work was supported by the Spanish Ministry of Economy and Competitiveness under projects MAT2017-83111R, MAT2017-85617-R, and PID2019- 106211RB-I00, by the Instituto de Salud Carlos III (PI16/ 00812), by the Comunidad Autonoma de Madrid (B2017/ ́ BMD-3867 RENIM-CM), and cofinanced by the European Structural and Investment Fun

Adjustable near-infrared fluorescence lifetime emission of biocompatible rare-earth-doped nanoparticles for in vivo multiplexing

Rare-earth-doped inorganic nanocrystals are an important class of nanoparticles for bioimaging applications due to the facility of providing them with tailored emissions in the visible and near-infrared regions of the electromagnetic spectrum. Recently it has become of interest to engineer the dopant composition of these materials in order to enable multiplexed lifetime imaging for autofluorescence-free in vivo bioimaging. Herein we report a simple approach to obtain different fluorescence lifetimes for the Yb3+emission (2F5/2 → 2F7/2) in Nd3+, Yb3+, Tm3+ co-doped NaGdF4 nanoparticles by only changing their crystal size while keeping their hydrodynamic diameter constant. This allowed straightforward transformation of infrared images in the time domain into lifetime maps. The particles were then deployed as in vivo contrast agents for near-infrared imaging in a mouse demonstrating their multiplexing capabilityThis work was financed by the Spanish Ministerio de Ciencia e Inovación under projects PID2019-106211RB-I00 and PID2020-118878RB-I00, by the Instituto de Salud Carlos III (PI19/00565), by the Comunidad Autónoma de Madrid (CAM) S2017/ BMD3867 RENIM-CM grant and co-financed by the European structural and investment fund. Additional funding was provided by the European Union Horizon 2020 FETOpen project NanoTBTech (801305), the CAM young investigator project SI3/PJI/2021-00211 the Fundación para la Investigación Biomédica del Hospital Universitario Ramón y Cajal project IMP21_A4 (2021/0427), and also by COST action CA17140. R. M. acknowledges the support of the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 797945 (LANTERNS). J.Y. acknowledges the support from the China Scholarship Council (CSC File No.201704910867

Nanoprobes for biomedical imaging with tunable near-infrared optical properties obtained via green synthesis

Ideally, any material used should be nontoxic and produced with safe, inexpensive, and energy-effective processes. In the case of optically active nanoparticles, this is often not the case, as they are frequently composed of hazardous heavy metals and/or produced with methods far from being environmentally friendly. Herein, the preparation of Ag2S-based nanoparticles via a simple green synthesis route is explored. Aqueous extracts of roasted coffee are used as sources of coordinating molecules. Optimization of the reaction conditions yields dimeric Ag Ag2S nanoparticles, whose near-infrared photoluminescence can be switched on via H2O2-mediated oxidation. This oxidation transforms suitable photoacoustic contrast agents into fluorescence imaging probes. Theoretical calculations further clarify the role of metallic silver in determining the optical properties of Ag2S. Overall, it is demonstrated that nanomaterials with tangible applicative potential can be prepared via cost- and energy-effective synthesis strategies that entail benign, renewable chemical

In vivo near-infrared imaging using ternary selenide semiconductor nanoparticles with an uncommon crystal structure

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 Ag2Se 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 Ag2S 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 systemJ.Y. acknowledges the support from the China Scholarship Council (CSC File No. 201704910867). R.M. acknowledges the support of the European Commission through the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 797945 (LANTERNS). P.R. is grateful for a Juan de la Cierva – Incorporación scholarship (IJC2019-041915-I). This work was supported by the Ministerio de Ciencia e Innovación de España under projects MAT2016-75362-C3-1-R, MAT2017-83111R, and MAT2017-85617-R, by the Instituto de Salud Carlos III (PI16/00812), by the Comunidad Autónoma de Madrid (B2017/BMD3867/RENIM-CM, PID2019-106211RB-I00), and cofinanced by the European Structural and investment fund. Additional funding was provided by the European Union Horizon 2020 FETOpen project NanoTBTech (801305), the Fundación para la Investigación Biomédica del Hospital Universitario Ramón y Cajal project IMP18_38 (2018/0265), and also by COST action CA17140. E.X. is grateful for a Juan de la Cierva Formación scholarship (FJC2018-036734-I

In Vivo Near-Infrared Imaging Using Ternary Selenide Semiconductor Nanoparticles with an Uncommon Crystal Structure

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 Ag2Se 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 Ag2S 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

Síntesis y caracterización de nanopartículas activa en el infrarrojo cercano para bioimagen

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de Materiales. Fecha de lectura: 18-01-202

Transformer-based comparative multi-view illegal transaction detection.

In recent years, as the Ether platform has grown by leaps and bounds. Numerous unscrupulous individuals have used illegal transaction to defraud large sums of money, causing billions of dollars of losses to investors worldwide. Facing the endless stream of the illegal transaction based on Ether smart contracts problems, such as illegal transaction, money laundering, financial fraud, phishing. Currently, illegal transaction are only detected by a single view of the smart contract's contract code view feature and account transaction view feature, which is not only incomplete, but also not fully representative of the smart contract's features. More importantly, the single view detection model cannot accurately capture the global structure and semantic features between the Tokens of the view features. In this case, it is particularly important that all view features are shared among themselves. In this paper, we investigate a Transformer-based model for contrasting illegal transaction detection networks under multiple views (TranMulti-View Net). The model in this paper is based on Transformer to learn a multi-view fusion representation, which aims to maximise the fusion of the interaction information of different view features under the same condition. In this model we first use the Transformer model to learn global structure and semantic features from a sequence of Tokens tokenised by a view, capturing the remote dependencies of Tokens in the view features, and then we share the contract code view features and the account transaction view features across all views to learn important semantic information between views from each other. In addition, we find that the approach of semi-supervised training of multi-view features using contrast learning outperforms the scheme of prediction based on direct fusion of different view features, resulting in stronger correlation between view features. As a result, the underlying semantic information can be captured more accurately, leading to more accurate predictions of illegal transaction. The experimental results show that our proposed TranMulti-View Net obtains good detection results with a Precision score of 98%

Performance of different illegal transaction contract detection models.

Performance of different illegal transaction contract detection models.</p

Represents the result of clustering by Kmeans after removing the full concatenation layer of the last layer in Tranmulti-View Net, and the best result is displayed in bold.

Represents the result of clustering by Kmeans after removing the full concatenation layer of the last layer in Tranmulti-View Net, and the best result is displayed in bold.</p

Comparison of access control technologies.

Comparison of access control technologies.</p