Functionalized Ultrabright Fluorescent Mesoporous Silica Nanoparticles

The problem of functionalization of recently reported ultrabright fluorescent mesoporous silica nanoparticles while preserving their fluorescent brightness is solved. This is a serious issue because of the open geometry of mesoporous channels and physical encapsulation of fluorescent dye inside those channels. Amine modification of mesoporous nanoparticles is described to preserve the brightness comparable to that of earlier reported ultrabright silica nanoparticles. Scaling to 40 nm sized particles, amine‐functionalized nanoparticle have fluorescent brightness equivalent to the one of 630 free rhodamine 6G (R6G) dye molecules in water. To demonstrate further most challenging functionalization, which relies on using organic‐solvent‐based chemistry, folic acid conjugation is developed. Two different methods are used to conjugate folites to the amine functionalities. Both methods result in a decrease of fluorescence intensity, which can nonetheless still be called ultrabright. The brightness can drop to either 310 or 80 R6G dye molecules per particle of nominal diameter of 40 nm.     

A Dual-Functional Ferroferric Oxide/Quantum Dots Theranostic Nanoplatform for Fluorescent Labeling and Photothermal Therapy

A biocompatible, nontoxic theranostic nanoplatform consisting of mesoporous silica-coated ferroferric oxide (Fe₃O₄) and Mn-doped ZnS-ZnS quantum dots (QDs) is synthesized via a layer-by-layer method. Transmission electron microscopy, X-ray diffractometer, magnetometry, and fluorophotometer are employed to characterize the nanoplatform. The nanoplatform exhibits excellent superparamagnetic, fluorescent, and light absorption properties. The template method is introduced to form a mesoporous silica structure on the nanoplatform, lowering the mass of the nanoplatform and effectively promoting the absorption efficiency of the incident light compared with the traditional silica layer. In addition, after endocytosis of the nanoplatform, cancer cells are easily detected under a fluorescence microscope because of the excellent fluorescent behavior of QDs. Moreover, in vitro experiments confirm that nanoplatform possesses perfect photothermal effect to destroy tumor cells under laser irradiation. Therefore, ferroferric oxide/QDs nanoplatforms, combined with the functions of fluorescent labeling and photothermal therapy for cancer cells, are expected to be a promising biopotential material in the field of diagnosis and treatment.     

Large Scale Synthesis of Highly Stable Fluorescent Carbon Dots Using Silica Spheres as Carriers for Targeted Bioimaging of Cancer Cells

In this paper, fluorescent carbon dots (CDs) loaded on silica (SiO₂) spheres are synthesized by the one‐pot hydrothermal route, and then folic acids (FA) are covalently conjugated on the surface of SiO₂ spheres. The formed SiO₂@CDs‐FA composites can target specific tissues, e.g., cancer. The key of this method is the employment of (3‐aminopropyl)trimethoxysilane as bridge joint, which not only serves as surface passivation agents allowing the large scale synthesis of CDs with high quantum yield, but also enables SiO₂@CDs composites further covalent conjugation of FA. The resultant SiO₂@CDs composites have many advantages such as easy separation and purification, highly stable, well water‐soluble, and biocompatible. Moreover, the SiO₂@CDs‐FA could be used as fluorescent probes for biological imaging in vitro. The uptake of the SiO₂@CDs‐FA into HeLa cells is receptor‐mediated endocytosis, which is confirmed by a comparative study using FR‐negative 293T cells. Findings from this study suggest that the SiO₂@CDs‐FA composites could be used as a platform for cancer diagnosis studies in various biological systems.     

A General Strategy to Encapsulate Semiconducting Polymers within PEGylated Mesoporous Silica Nanoparticles for Optical Imaging and Drug Delivery

Although semiconducting polymers (SPs) have become an important category for optical imaging and phototherapy, their biomedical application is still facing a number of challenges. Herein, a cationic surfactant–assisted approach to encapsulate hydrophobic SPs within highly PEGylated mesoporous silica (mSiO₂) nanoparticles with excellent colloidal stability and enhanced fluorescence in aqueous solution is reported. In comparison to the previously reported amphiphilic polymer coating and silification method, this universal strategy not only suppresses the formation of empty polymer micelles and free silica nanoparticles, but also provides high specific surface area for drug loading. As a proof of concept, furan-containing diketopyrrolopyrrole-based semiconducting polymers (PDFT) are coated with mesoporous silica and utilized for fluorescence imaging in the second near-infrared region (NIR-II, 1000–1700 nm) and drug delivery. In vivo blood vessel imaging and tumor imaging are achieved with high resolution (0.21 mm) and signal-to-background ratio (≈4.2). Additionally, pH-responsive drug release and improved therapeutic effect are observed. By choosing desired SPs, different optical imaging and therapeutic modalities can also be achieved, thus the SP@mSiO₂ nanostructures obtained here provide numerous opportunities for theranostic applications.     

基于InP@ZnS QDs/Dured纳米荧光探针的DNA检测

利用巯基丙酸包覆的In P@Zn S量子点(QDs)与Dured构建了一种检测DNA的荧光探针。在该探针中,以环境友好型带负电的In P@Zn S量子点为荧光团,与带正电的Dured通过静电结合,构建了In P@Zn S QDs/Dured纳米荧光探针。通过荧光共振能量转移(FRET)机理,量子点荧光被猝灭;当DNA存在时,Dured与DNA的特异性结合使Dured从In P@Zn S QDs表面脱附,FRET过程被打断,In P@Zn S QDs荧光恢复,以荧光"关-开"方式检测DNA。该探针检测DNA的线性范围为2.0~275.0 ng·L-1,检测限为1.0 ng·L-1,并可用于模拟生物生理条件下的DNA检测。     

半导体聚合物纳米荧光探针的制备及生物应用研究进展

半导体聚合物作为功能有机高分子材料被广泛应用于有机光电子器件领域的研究。近年来由半导体聚合物构成的荧光纳米粒子引起了广泛的研究兴趣。这类新型纳米探针具有光学吸收截面大、量子效率高、辐射跃迁速率快、光稳定性好等特性,在荧光成像和生物传感等领域获得了重要应用。本文简要概述了近年来半导体聚合物纳米粒子的研究进展,包括其光物理性质、表面功能化以及在细胞标记、体内成像、生物传感、单粒子示踪、药物输送和光动力学疗法等领域的应用。     

Tunable and High Photoluminescence Quantum Yield from Self‐Decorated TiO2 Quantum Dots on Fluorine Doped Mesoporous TiO2 Flowers by Rapid Thermal Annealing

Herein a novel approach is reported to achieve tunable and high photoluminescence (PL) quantum yield (QY) from the self‐grown spherical TiO₂ quantum dots (QDs) on fluorine doped TiO₂ (F‐TiO₂) flowers, mesoporous in nature, synthesized by a simple solvothermal process. The strong PL emission from F‐TiO₂ QDs centered at ≈485 nm is associated with shallow and deep traps, and a record high PL QY of ≈5.76% is measured at room temperature. Size distribution and doping of F‐TiO₂ nanocrystals (NCs) are successfully tuned by simply varying the HF concentration during synthesis. During the post‐growth rapid thermal annealing (RTA) under vacuum, the arbitrary shaped F‐TiO₂ NCs transform into spherical QDs with smaller sizes and it shows dramatic enhancement (≈163 times) in the PL intensity. Electron spin resonance (ESR) and X‐ray photoelectron spectroscopy (XPS) confirm the high density of oxygen vacancy defects on the surface of TiO₂ NCs. Confocal fluorescence microscopy imaging shows bright whitish emission from the F‐TiO₂ QDs. Low temperature and time resolved PL studies reveal that the ultrafast radiative recombination in the TiO₂ QDs results in highly efficient PL emission. A highly stable, biologically inert, and highly fluorescent TiO₂ QDs/flowers without any capping agent demonstrated here is significant for emerging applications in bioimaging, energy, and environmental cleaning.     

Fe_3O_4@SiO_2@CdTe磁性荧光复合微球的制备与表征

采用水热合成法和Stber法制备了氨基功能化SiO2包覆的Fe3O4磁性纳米微球Fe3O4@SiO2-NH2,它与巯基乙酸修饰的CdTe量子点通过酰胺缩合反应,将量子点键合到磁性微球上,制备出单分散性的Fe3O4@SiO2@CdTe磁性荧光双功能微球.用透射电子显微镜、X-射线衍射仪、荧光分光光度计、振动样品磁强计表征了该纳米复合微球的结构和性能.结果表明:Fe3O4@SiO2@CdTe磁性荧光复合微球单分散性好,平均粒径为470nm,饱和磁化强度为37.9emu/g,具有良好的超顺磁性和较高的荧光发光效率.     

Optical Properties of Ag and Au Nanoparticles Dispersed within the Pores of Monolithic Mesoporous Silica

The optical absorption of silver and gold nanoparticles dispersed within the pores of monolithic mesoporous silica upon annealing at elevated temperatures has been investigated. With decreasing particle size, the surface plasmon resonance position of the particles blue-shifts first and then red-shifts for silver/silica samples, but only red-shifts for gold/silica samples. This size evolution of the resonance position is completely different from that previously reported for fully embedded particles. We assume a local porosity at the particle/matrix interface, such that free surface of particles within the pores may be in contact with ambient air, and present a two-layer core/shell model to calculate the optical properties. These calculations also consider deviations from the optical constants of bulk matter to account for corresponding effects below about 10 nm particle size. From the good agreement between experimental results and model calculations, we conclude a peculiar particle/ambience interaction dominating the size evolution of the resonance. Because of the difference of core electron structure, the relative importance of the effects of local porosity and free surface, respectively, are different for silver and gold. For silver, the effect of the local porosity is stronger, but for gold the opposite is found.     

Glutathione‐Mediated Degradation of Surface‐Capped MnO2 for Drug Release from Mesoporous Silica Nanoparticles to Cancer Cells

Owing to its higher concentration in cancer cells than that in the corresponding normal cells, glutathione (GSH) provides an effective and flexible mechanism to design drug delivery systems. Here a novel GSH‐responsive mesoporous silica nanoparticle (MSN) is reported for controlled drug release. In this system, manganese dioxide (MnO₂) nanostructure, formed by the reduction of KMnO₄ on the surface of carboxyl‐functionalized MSN can block the pores (MSN@MnO₂). By a redox reaction, the capped MnO₂ nanostructure can dissociate into Mn²⁺ in the presence of GSH molecules. The blocked pores are then uncapped, which result in the release of the entrapped drugs. As a proof‐of‐concept, doxorubicin (DOX) as model drug is loaded into MSN@MnO₂. DOX‐loaded MSN@MnO₂ shows an obvious drug release in 10 × 10^?3 m GSH, while no release is observed in the absence of GSH. In vitro studies using human hepatocellular liver carcinoma cell line (HepG2) prove that the DOX‐loaded MSN@MnO₂ can entry into HepG2 cells and efficiently release the loaded DOX, leading to higher cytotoxicity than to that of human normal liver cells (L02). It is believed that further developments of this GSH‐responsive drug delivery system will lead to a new generation of nanodevices for intracellular controlled delivery.     

希夫碱与介孔分子筛纳米超分子材料的发光

合成了希夫碱N,N′2亚水杨基1,4苯二胺(L1)、4[2羟基1萘甲醛基]苯甲酸(L2)和4[2羟基1苯甲醛基]苯甲酸(L3)。使用1HNMR、IR、UV和元素分析手段对希夫碱的结构进行表征。荧光光谱表明固体粉末希夫碱的L1、L2和L3具有较强的光致发光性能,多个精细特征激发峰,其荧光强度大小顺序为L1>L2>L3。荧光时间分辨实验表明,L1、L2和L3的荧光寿命分别为199,199,214ns。L1、L2和L3在乙醇溶液中荧光强度的顺序则为L3>L2>L1。希夫碱L3、L2和L1的乙醇溶液的荧光量子产率大小分别为0.60,0.56和0.0086。希夫碱L1、L2或L3与(CH3)3Si MCM41超分子材料的发光强度比与MCM41组装的强,说明疏水的分子筛环境有利于客体的发光。客体分子L1、L2和L3的激发光谱存在多个精细的激发峰,最大激发波长皆为468nm。希夫碱L1、L2或L3与分子筛形成的超分子材料的发射峰一般朝短波方向移动;L1、L2与(CH3)3Si MCM41及L2、L3与MCM41组装形成超分子体系后,最大激发峰分别红移到529,507,507,505nm;超分子MCM41L1和(CH3)3Si MCM41L3的最大激发峰波长则保持不变。L1、L2和L3分别与(CH3)3Si MCM41形成的超分子体系的荧光寿命则有较大的变化;而L1、L2和L3分别与MCM41形成超分子体系的荧光寿命几乎没有发生变化。荧光时间分辨实验说明主体对希夫碱客体具有很强的选择性。     

Mesoporous Silica Promoted Deposition of Bioinspired Polydopamine onto Contrast Agent: A Universal Strategy to Achieve Both Biocompatibility and Multiple Scale Molecular Imaging

Polydopamine (PDA) preserves universal coating and metal‐binding ability, and is suitable for application in synthesizing multifunctional agents. Herein, utilizing mesoporous silica assisted deposition to enhance both heterogeneous nucleation and loading amounts of PDA, the magnetic resonance (MR) T₁ component (PDA‐Fe³⁺) and MR T₂/computed tomography (CT)/multiphoton luminescence (MPL) component (FePt) have been successfully integrated in aqueous solution. This four‐in‐one (T₁, T₂, CT, MPL) imaging nanocomposite, FePt@mSiO₂ @PDA‐polyethylene glycol (PEG), demonstrated its multi‐imaging power both in vitro/in vivo. According to our in vitro/in vivo results, FePt@mSiO₂@PDA‐PEG reveals water‐content‐dependent property in T₁ MR imaging, which suggests the necessity of having dual‐modal MR ability in a single particle for the precision diagnosis. Most importantly, this dual (T₁,T₂)‐MRI/CT contrast agent is demonstrated complementary to each other in the in vivo testing. PDA coated mesoporous silica also offers an advantage of delayed degradation that prevents adverse effects caused by silica fragments before excretion. The potential of this nanocomposites in both drug carrier and photothermal agent was further evaluated by using doxorubicin and monitoring solution temperature after irradiating 808 nm continuous‐wave, respectively The merits of controlled polymerization, enhanced PDA loading, and biofavorable degradation make this methodology promising to other nanoparticle@mSiO₂ for a wide range of bioapplications.     

H2O2水热合成双峰介孔硅MCM-48球

在温和的条件下,通过H₂O₂水热处理预合成的MCM-48,得到了有序的双峰介孔硅MCM-48球． 结果表明H₂O₂对于同时去除有机模板剂及形成双峰介孔硅MCM-48球具有重要的作用．采用XRD、TEM、FT-IR和N₂吸附-解吸等方法对双峰介孔MCM-48材料进行了表征,对双峰介孔MCM-48的形成机理也进行了探讨．     

Facile Synthesis of Single‐Phase Mesoporous Gd2O3:Eu Nanorods and Their Application for Drug Delivery and Multimodal Imaging

In this work, a new and facile strategy is developed to synthesize a single‐phase Eu³⁺‐doped mesoporous gadolinium oxide nanorods (MS‐Gd₂O₃:Eu@PEG) by incorporating a facile wet‐chemical route, which includes an induced silica layer being coated onto the nanorods, and evolution of pores and formation of channels, as well as a surface‐modified process for multimodal imaging and anti‐cancer drug delivery. The properties of these as‐prepared Gd₂O₃:Eu nanorods are characterized by transmission electron microscopy (TEM), X‐ray diffraction (XRD), N₂ adsorption/desorption, and photoluminescence (PL). The in vitro cytotoxicity test, drug loading, and drug release experiments reveal that the MS‐Gd₂O₃:Eu@PEG nanorods have good biocompatibility, efficient loading capacity, and pH‐sensitive releasing behavior, suggesting the nanorods could be an ideal candidate as drug delivery vehicles for cancer therapy. Furthermore, the MS‐Gd₂O₃:Eu@PEG nanorods show clearly dose‐dependent contrast enhancement in T₁‐weighted magnetic resonance images and can potentially be used as a T₁‐positive contrast agent. These results indicate our prepared multifunctional mesoporous gadolinium oxide nanorods can serve as a promising platform for simultaneous anti‐cancer drug delivery and multimodal imaging.     

Rapid Visualization of Latent Fingerprints with Color‐Tunable Solid Fluorescent Carbon Dots

Latent fingerprints (LFPs) imaging is the most important approach to identify individuals, and there is a persisting need for the development of simple, rapid, accurate, and universal LFPs recognition methods. The nitrogen‐ and sulfur‐doped solid fluorescent carbon dots (N,S‐SFCD) are synthesized with a simple microwave‐assisted method by using l ‐glutathione and citric acid as precursors. The obtained N,S‐SFCD has a uniform size from 2 to 7 nm with quantum yield over 48%. The presence of heteroatoms and functional groups on the surface endows the N,S‐SFCD with good dispersibility and strong fluorescence emission, and overcomes the typical aggregation‐induced fluorescence quenching, thus allowing the N,S‐SFCD to be used in both solution and their powder forms. Furthermore, the color‐tunable fluorescence, electrostatic interaction with fingerprints, and good stability enable N, S‐SFCD to act as an excellent chemosensor for fluorescence imaging. LFPs are detected with high resolution through powder method, and their second‐ and third‐level substructures are clearly identified. The method is validated for LFPs visualization on various substrates, and aged (7, 15, and 30 d) LFPs can also be successfully stained with N,S‐SFCD. The results demonstrate that the N,S‐SFCD as a developer has great potential in LFPs imaging for forensic investigations.     

基于CdSe@ZnS量子点水溶性纳米粒子的制备及荧光性能

作为一种新型的荧光探针,量子点（QD）已经受到越来越多的重视,制备工艺也显得格外重要。水相中合成的量子点效率低,油相中的量子点经过转相以后效率也大大衰减。本论文利用再沉淀包覆的方法制备了具有良好的水溶性的掺杂绿光CdSe@ZnS的纳米颗粒G-NPs（534 nm）和掺杂红光CdSe@ZnS的纳米颗粒R-NPs（610 nm）,具有窄的半峰宽（G-NPs~29 nm,R-NPs~31 nm）,较小的粒径（45 nm）,并在此基础上通过发射光谱与荧光衰减研究了量子点之间的能量传递现象。该方法保留了量子点原来的性质,基于其优良的光学性质,对人类肝细胞肝癌细胞株（HepG2）进行了荧光标记,从共聚焦成像实验结果看出,纳米颗粒得到了良好的吞噬效果。     

SiO_2/Ag核壳结构纳米粒子的制备及其表面荧光增强

以罗丹明B掺杂的SiO2球为核,通过化学还原的方法制备了二氧化硅/银核壳结构复合纳米粒子。采用透射电镜(TEM)、紫外-可见-近红外(UV-Vis-NIR)分光光度计和荧光分光光度计对二氧化硅/银核壳结构纳米粒子的表面形貌、表面等离子共振和表面荧光增强特性进行了研究和表征。结果表明,二氧化硅/银核壳结构纳米粒子的表面等离子共振峰具有明显的可调谐性,且其表面荧光增强强烈依赖于银壳层的表面等离子共振,随银壳层厚度的增大而增强。     

氮掺杂碳量子点的合成及作为荧光探针对Hg~(2+)的检测

与传统量子点相比,碳量子点作为一种新型的荧光碳纳米材料,由于其良好的生物相容性、易于表面功能化、低毒性等优点受到了广泛关注。采用柠檬酸为碳源,氨水为氮源,热解法制备出水溶性好的氮掺杂碳量子点(NCDs)。透射电镜(TEM)观察NCDs的粒径在3nm左右;X射线光电子能谱(XPS)和傅里叶红外光谱(FIIR)证明NCDs的表面被羧基、氨基、羟基、羰基等官能团功能化,说明NCDs有很好的水溶性。研究还发现Hg~(2+)对NCDs的荧光有良好的猝灭作用,可作为荧光探针检测水中Hg~(2+)含量。在PBS缓冲液中(0.1mol·L~(-1) pH 7.0),NCDs的荧光猝灭率(F/F0)与汞离子浓度在0.001~0.1μmol·L~(-1)之间存在良好的线性关系,检出限为2.1nmol·L~(-1)。该方法灵敏度高、选择性好、方法简便,可应用于Hg~(2+)快速、灵敏的检测。