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1.
    
Anticounterfeiting materials are used to distinguish real banknotes, products, and documents from counterfeits, fakes, or unauthorized replicas. However, conventional anticounterfeiting materials generally exhibit a single anticounterfeiting function, resulting in a low level of security. Herein, a novel anticounterfeiting nanocomposite is demonstrated with numerous prominent security features. The nanocomposite is fabricated by doping upconverting nanoparticles (UCNPs) in a photoresponsive azobenzene-containing polymer (azopolymer). Because of the cis–trans photoisomerization of the azopolymer, the nanocomposite exhibits photoinduced reversible color changes suitable for anticounterfeiting applications. Additionally, the hard nanocomposite can be converted to a rubber-like soft solid by light irradiation. Imprinted microstructures are fabricated on the photosoftened nanocomposite, which result in photonic colors. Moreover, polarization-dependent structures are fabricated on the nanocomposite via photoinduced orientation for encryption. Importantly, UCNPs in the nanocomposite emit visible light upon excitation by near-infrared light, enabling the observation of various anticounterfeiting structures with high contrast. An advantage of the anticounterfeiting nanocomposite is that the security features can be observed by the naked eye for quick discrimination and can be analyzed using laboratory equipment for higher accuracy. The anticounterfeiting nanocomposite is easily processed on paper, glass, and plastic, which demonstrates its potential anticounterfeiting functions for banknotes, wines, and medicines.  相似文献   

2.
    
The ability to optically induce biological responses in 3D has been dwarfed by the physical limitations of visible light penetration to trigger photochemical processes. However, many biological systems are relatively transparent to low-energy light, which does not provide sufficient energy to induce photochemistry in 3D. To overcome this challenge, hydrogels that are capable of converting red or near-IR (NIR) light into blue light within the cell-laden 3D scaffolds are developed. The upconverted light can then excite optically active proteins in cells to trigger a photochemical response. The hydrogels operate by triplet–triplet annihilation upconversion. As proof-of-principle, it is found that the hydrogels trigger an optogenetic response by red/NIR irradiation of HeLa cells that have been engineered to express the blue-light sensitive protein Cry2olig. While it is remarkable to photoinduce the clustering of Cry2olig with blanket NIR irradiation in 3D, it is also demonstrated how the hydrogels trigger clustering within a single cell with great specificity and spatiotemporal control. In principle, these hydrogels may allow for photochemical control of cell function within 3D scaffolds, which can lead to a wealth of fundamental studies and biochemical applications.  相似文献   

3.
    
Layer‐by‐Layer (LbL) assembly is a simple and highly versatile method to modify surfaces and fabricate robust and highly‐ordered nanostructured coatings over almost any type of substrate. Such versatility enables the incorporation of a plethora of building blocks, including materials exhibiting switchable properties, in a single device through a multitude of complementary intermolecular interactions. Switchable materials may undergo reversible physicochemical changes in response to a variety of external triggers. Although most of the works in the literature have been focusing on stimuli‐responsive materials that are sensitive to common triggers such as pH, ionic strength, or temperature, much less has been discussed on LbL systems which are sensitive to non‐invasive and easily controlled light stimulus, despite its unique potential. This review provides a deep overview of the recent progresses achieved in the design and fabrication of light‐responsive LbL polymeric multilayer systems, their potential future challenges and opportunities, and possible applications. Many examples are given on light‐responsive polymeric multilayer assemblies built from metal nanoparticles, functional dyes, and metal oxides. Such stimuli‐responsive functional materials, and combinations among them, may lead to novel and highly promising nanostructured smart functional systems well‐suited for a wide range of research fields, including biomedicine and biotechnology.  相似文献   

4.
    
Preclinical studies of nanoparticles for pulmonary therapeutics are often performed on 2D cell cultures or in vitro models that do not include a mucus barrier. However, the mucus layer lining the lungs is an essential barrier for drugs to permeate in order to exert a therapeutic effect. Herein, the role of surface coating of lanthanide-doped upconverting nanoparticles (UCNPs) and their interaction with the mucus barrier are explored using a patient-derived 3D cell culture model. The upconverted emissions from the UCNPs are used to track them throughout the 3D model and study their localization as a function of administration time and mucus thickness. Positively charged, ligand-free, and negatively charged, supported lipid bilayer-coated UCNPs are evaluated. A substantial difference in the residence time in mucus and mucociliary clearance of each type of UCNP is observed in a realistic and relevant model. As such, these results underscore the need for preclinical investigations in tissue models, especially with respect to the surface properties of the nanoparticles under study.  相似文献   

5.
    
Paramagnetic gadolinium (Gd‐III)‐ion‐doped upconversion nanoparticles (UCNPs) are attractive optical‐magnetic molecule imaging probes and are a highly promising nanoplatform for future theranostic nanomedicine design. However, the related relaxivity mechanism of this contrast agent is still not well understood and no significant breakthrough in relaxivity enhancement has been achieved. Here, the origin and optimization of both the longitudinal (r1) and transverse (r2) relaxivities are investigated using models of water soluble core@shell structured Gd3+‐doped UCNPs. The longitudinal relaxivity enhancement of the nanoprobe is demonstrated to be co‐contributed by inner‐and outer‐sphere mechanisms for ligand‐free probes, and mainly by outer‐sphere mechanism for silica‐shielded probes. The origin of the transverse relaxivity is inferred to be mainly from an outer‐sphere mechanism regardless of surface‐coating, but with the r2 values highly related to the surface‐state. Key factors that influence the observed relaxivities and r2/r1 ratios are investigated in detail and found to be dependent on the thickness of the NaGdF4 interlayer and the related surface modifications. A two orders of magnitude (105‐fold) enhancement in r1 relaxivity and 18‐fold smaller r2/r1 ratio compared to the first reported values are achieved, providing a new perspective for magnetic resonance (MR) sensitivity optimization and multimodality biological imaging using Gd3+‐doped UCNPs.  相似文献   

6.
    
The hypoxic hallmark of tumor has aroused substantial burdens on a variety of therapeutic modalities including photodynamic therapy (PDT). Recently, biological oxygen evolution enabled by photosynthetic cyanobacterial cells has emerged as one of the most advanced and promising tissue oxygenation strategies, which is particularly beneficial for in situ tumor-PDT. Herein, a near infrared-driven PDT platform based on the photosynthetic cyanobacterial cells hybridized with photosensitizer rose bengal (RB)-loaded upconversion nanoparticles, named as UR-Cyan cells, is reported. Upon the irradiation of 980 nm laser and its upconversions to shorter wavelengths, the formulated UR-Cyan cells are both photosynthetically active for oxygen production and photosensitive for the subsequent singlet oxygen generation by the photosensitizer, resulting in enhanced and sustainable PDT efficacy against tumor cells/tissues. The present design offers a practical approach to conquer the hypoxic burden of PDT operations against a wide range of pathological lesions with excellent biocompatibility and clinical promises.  相似文献   

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8.
    
Multimodal bio‐imaging has attracted great attention for early and accurate diagnosis of tumors, which, however, suffers from the intractable issues such as complicated multi‐step syntheses for composite nanostructures and interferences among different modalities like fluorescence quenching by MRI contrast agents (e.g., magnetic iron oxide NPs). Herein, the first example of T2‐weighted MR imaging of Ho3+‐doped upconversion nanoparticles (UCNPs) is presented, which, very attractively, could also be simultaneously used for upconversion luminesence (UCL) and CT imaging, thus enabling high performance multi‐modal MRI/UCL/CT imagings in single UCNPs. The new finding of T2‐MRI contrast enhancement by integrated sensitizer (Yb3+) and activator (Ho3+) in UCNPs favors accurate MR diagnosis of brain tumor and provides a new strategy for acquiring T2‐MRI/optical imaging without fluorescence quenching. Unlike other multi‐phased composite nanostructures for multimodality imaging, this Ho3+‐doped UCNPs are featured with simplicity of synthesis and highly efficient multimodal MRI/UCL/CT imaging without fluorescence quenching, thus simplify nanostructure and probe preparation and enable win–win multimodality imaging.  相似文献   

9.
    
Developing photoactive nanosystems against microbial infection and its therapeutic application is compromised by the lack of suitable materials or molecular dyes activatable at biofriendly NIR light. In this direction, the upconverting nanoparticles based on core–shell lanthanide-doped nanoclusters are developed synthetically to achieve a broad range of NIR-active phototherapeutic antimicrobial agents. This review illustrates antimicrobial photodynamic therapy (aPDT) and multimodal therapy by NIR photoirradiation, generated by lanthanum doped upconverting nanoparticles (UCNPs). The objective herein is to discuss the insights in developing the UCNPs for designing efficient aPDTs and their efficacies against emerging antibiotic-resistant bacterial colonies and their biofilms, drug-resistant fungi, and viruses. The biosafety and biocompatibility of UCNPs at both in vitro and in vivo level are also presented in detail. Finally, our perspectives on the ways of future material engineering needed for the effective translation into their real-world applications are also commented.  相似文献   

10.
    
Theranostic nanoagents targeted for personalized medicine provide a unified platform for therapeutics and diagnostics. To be able to discretely control each individually, allows for safer, more precise, and truly multifunctional theranostics. Rare earth doped nanoparticles can be rationally tailored to best match this condition with the aid of core/shell engineering. In such nanoparticles, the light‐mediated theranostic approach is functionally decoupled—therapeutics or diagnostics are prompted on‐demand, by wavelength‐specific excitation. These decoupled rare earth nanoparticles (dNPs) operate entirely under near‐infrared (NIR) excitation, for minimized light interference with the target and extended tissue depth action. Under heating‐free 806 nm irradiation, dNPs behave solely as high‐contrast NIR‐to‐NIR optical markers and nanothermometers, visualizing and probing the area of interest without prompting the therapeutic effect beforehand. On the contrary, 980 nm NIR irradiation is upconverted by the dNPs to UV/visible light, which triggers secondary photochemical processes, e.g., generation of reactive oxygen species by photosensitizers coupled to the dNPs, causing damage to cancer cells. Additionally, integration of NIR nanothermometry helps to control the temperature in the vicinity of the dNPs avoiding possible overheating and quenching of upconversion (UC) emission, harnessed for photodynamic therapy. Overall, a new direction is outlined in the development of state‐of‐the‐art rare earth based theranostic nanoplatforms.  相似文献   

11.
    
Upconverting NaYF4:Yb3+,Er3+/NaYF4 core‐shell (CS) nanoparticles (NPs) were synthesized by thermal decomposition of lanthanide trifluoroacetate precursors and mixed with TiO2 NPs to fabricate dye‐sensitized solar cells (DSSCs). The CS geometry effectively prevents the capture of electrons because of the surface states and improves photo‐emission. The as‐synthesized CS NPs show upconversion (UC) luminescence, converting near infrared (NIR) light into visible light (450–700 nm), making the photon absorption by the ruthenium‐based dyes (which have little or no absorption in the NIR region) possible. The champion DSSCs fabricated using CS UC NPs (average size = 25 nm) show enhancements of ~12.5% (sensitized with black/N749 dye) and of ~5.5% (sensitized with N719 dye) in overall power conversion efficiency under AM 1.5G illumination. This variation in the enhancement of the DSSC efficiencies for black and N719 dyes is attributed to the difference in the extinction coefficient and the absorption wavelength range of dyes. Incident photon‐to‐current conversion efficiency measurements also evidently showed the photocurrent enhancement in the NIR region of the spectrum because of the UC effect. The results prove that the augmentation in efficiency is primarily due to NIR to visible spectrum modification by the fluorescent UC NPs. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

12.
    
Porous silicon (pSi) is emerging as a promising material in the development of nanovectors for the systemic delivery of therapeutic and imaging agents. The integration of photolithographic patterning, typical of the semiconductor industry, with electrochemical silicon etching provides a highly flexible strategy to fabricate monodisperse and precisely tailored nanovectors. Here, a microfabrication strategy for direct lithographic patterning of discoidal pSi particles is presented that enables precise and independent control over particle size, shape, and porous structure. Discoidal pSi nanovectors with diameters ranging from 500 to 2600 nm, heights from 200 to 700 nm, pore sizes from 5 to 150 nm, and porosities from 40 to 90% are demonstrated. The degradation in serum, interaction with immune and endothelial cells in vitro, and biodistribution in mice bearing breast tumors are assessed for two discoidal nanovectors with sizes of 600 nm × 400 nm and 1000 nm × 400 nm. It is shown that both particle types are degraded after 24 h of continuous gentle agitation in serum, do not stimulate cytokine release from macrophages or affect endothelial cell viability, and accumulate up to about 10% of the injected dose per gram tissue in orthotopic murine models of breast cancer. The accumulation of the discoidal pSi nanovectors into the breast tumor mass is found to be up to five times higher than for spherical silica beads with similar diameters.  相似文献   

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14.
    
Photodynamic therapy (PDT) is a noninvasive and site‐specific therapeutic technique for the clinical treatment of various of superficial diseases. In order to tuning the operation wavelength and improve the tissue penetration of PDT, rare‐earth doped upconversion nanoparticles (UCNPs) with strong anti‐stokes emission are introduced in PDT recently. However, the conventional Yb3+‐sensitized UCNPs are excited at 980 nm which is overlapped with the absorption of water, thus resulting in strong overheating effect. Herein, a convenient but effective design to obtain highly emissive 795 nm excited Nd3+‐sensitized UCNPs (NaYF4:Yb,Er@NaYF4:Yb0.1Nd0.4@NaYF4) is reported, which provides about six times enhanced upconversion luminescence, comparing with traditional UCNPs (NaYF4:Yb,Er@NaYF4). A colloidal stable and non‐leaking PDT nanoplatform is fabricated later through a highly PEGylated mesoporous silica layer with covalently linked photosensitizer (Rose Bengal derivative). With as‐prepared Nd3+‐sensitized UCNPs, the nanoplatform can produce singlet oxygen more effective than traditional UCNPs. Significant higher penetration depth and lower overheating are demonstrated as well. All these features make as‐prepared nanocomposites excellent platform for PDT treatment. In addition, the nanoplatform with uniform size, high surface area, and excellent colloidal stability can be extended for other biomedical applications, such as imaging probes, biosensors, and drug delivery vehicles.  相似文献   

15.
    
Constructing near-infrared light (NIR) light-enhanced room temperature gas sensors is becoming more promising for practical application. In this study, learning from the structure and photosynthetic process of chlorophyll thylakoid membranes in plants, the first “Thylakoid membrane” structural formaldehyde (HCHO) sensor is constructed by matching the upconversion emission of the lanthanide-doped upconversion nanoparticles (UCNPs) and the UV–vis adsorption of the as-prepared nanocomposites. The NIR-mediated sensor exhibits excellent performances, including ultra-high response (Ra / Rg = 2.22, 1 ppm), low practical limit of detection (50 ppb), reliable repeatability, high selectivity, and broadband spectral response. The practicality of the NIR-mediated gas sensor is confirmed through the remote and external stimulation test. A study of sensing mechanism demonstrates that it is the UCNPs-based light transducer produces more light-induced oxygen species for gas response in the process of non-radiative/radiative energy transfer, playing a key role in significantly improving the sensing properties of the sensor. The universality of NIR-mediated gas sensors based on UCNPs is verified using ZnO, In2O3, and SnO2 systems. This work paves a way for fabricating high-performance NIR-mediated gas sensors and will expand the application fields of NIR light.  相似文献   

16.
    
Nanotechnology seeks to mimic what nature has achieved: self‐assembly at the nanometer scale. Viral nanoparticles (VNPs) provide natural examples of self‐assembled architectures with unique structural and chemical properties. Here, the utilization of an archaeal virus, Sulfolobus islandicus rod‐shaped virus 2 (SIRV2), as a template for site‐selective and spatially controlled bioconjugation is described. SIRV2 is a virus of a hyperthermophilic and acidophilic host, the archaeon S. islandicus growing optimally at 80 °C and pH 3, and is thus, by its nature, an extremely stable VNP. The stability of SIRV2 in different solvent/water mixtures is monitored, and it is found that in other, non‐natural harsh conditions the VNPs also remained intact. Further, the question of whether the particles offer attachment sites allowing for selective chemical modification and decoration with functional ligands using biotin as a probe is addressed. It is found that carboxylate‐, carbohydrate‐ and amine‐selective chemistries are applicable and various biotinylated SIRV2 formulations can be fabricated. Depending on the chemistry and hence attachment site used, the display of the biotin labels can be spatially controlled at the virus body and at the ends. Labeling studies also provide novel insights into the structural properties of SIRV2, indicating that the major coat protein (CP) forms the virus body while the minor CP is located in the tail fibers at the end of the particles. Overall, SIRV2 represents an extremely stable and structurally interesting VNP with the potential for novel nanobiotechnological applications.  相似文献   

17.
    
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18.
金属包层渐变折射率平板波导传播特性   总被引：1，自引：0，他引：1  
本文采用多层线型分割近似，结合欧姆损耗微扰法，分析了金属包层渐变折射率平板波导的传播特性。按此方法计算了几类典型波导的传播常数数值，结果均与精确值相吻合，且物理概念清楚，计算方法简单。  相似文献   

19.
    
Pancreatic cancer has one of the highest fatality rates of all diseases, but poor drug availability after intravenous (IV) administration has hindered the diagnosis and treatment of patients. Herein, the authors report a novel strategy, combining intraperitoneal administration and phosphatidylcholine‐camouflaged NaLuF4:Yb,Tm/NaLuF4/NaDyF4 upconversion nanoparticles (UCNP@PC) to gain the enhanced dual‐modal imaging (upconversion luminescence/magnetic resonance imaging) of orthotopic pancreatic cancer. Remarkably, the authors observe a 16‐fold improvement in the efficacy of utilization promoted intraperitoneally administered UCNP@PC in monitoring orthotopic pancreatic cancer compared with IV approach. Benefiting from modification with phosphatidylcholine, a major component of cell membranes, the optimized nanostructures show excellent biocompatibility and are rapidly excreted via the bile pathway after their intraperitoneal administration. The integration of the advanced design of UCNP@PC and the optimal drug administration route also give a general strategy for the advanced diagnosis and treatment of a series of intraperitoneal cancers.  相似文献   

20.
    
Optical techniques used in medical diagnosis, surgery, and therapy require efficient and flexible delivery of light from light sources to target tissues. While this need is currently fulfilled by glass and plastic optical fibers, recent emergence of biointegrated approaches, such as optogenetics and implanted devices, calls for novel waveguides with certain biophysical and biocompatible properties and desirable shapes beyond what the conventional optical fibers can offer. To this end, exploratory efforts have begun to harness various transparent biomaterials to develop waveguides that can serve existing applications better and enable new applications in future photomedicine. Here, the recent progress in this new area of research for developing biomaterial‐based optical waveguides is reviewed. It begins with a survey of biological light‐guiding structures found in plants and animals, a source of inspiration for biomaterial photonics engineering. The review then describes natural and synthetic polymers and hydrogels that offer appropriate optical properties, biocompatibility, biodegradability, and mechanical flexibility have been exploited for light‐guiding applications. Finally, perspectives on biomedical applications that may benefit from the unique properties and functionalities of light‐guiding biomaterials are discussed briefly.  相似文献   

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