A label-free sensing method for phosphopeptides using two-layer gold nanoparticle-based localized surface plasma resonance spectroscopy

In this study, a new type of localized surface plasmon resonance (LSPR) sensing substrate for phosphopeptides was explored. It has been known that LSPR response for target species is larger in the near-infrared region (NIR) than in the visible region of the electromagnetic spectrum. Several types of noble metal nanoparticles (NPs) with NIR absorption capacities have been previously demonstrated as effective LSPR-sensing nanoprobes. Herein, we demonstrate a straightforward approach with improved sensitivity by simply using layer-by-layer (LBL) spherical Au NPs self-assembled on glass slides as the LSPR-sensing substrates that are responsive in the NIR region of the electromagnetic spectrum. The modified glass slide acquired an LSPR absorption band in the NIR, which resulted from the dipole–dipole interactions between Au NPs. To enable the chip to sense phosphopeptides, the surface of the glass chip was spin-coated with thin titania film (TiO₂-Glass@Au NPs). Absorption spectrophotometry was employed as a detection tool. Tryptic digest of α-casein was used as a model sample. The feasibility of using the new LSPR approach for detecting a potential risk factor leading to cancers (i.e., phosphorylated fibrinopeptide A) directly from human serum samples was demonstrated. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was used to confirm the results.     

Ag-PVA和Ag-PVA/TiO2复合超薄膜的制备及性能研究

用3种方法制备了银纳米粒子-聚乙烯醇复合体系,其中用加热还原法所得体系中Ag纳米粒子的尺寸较大(15nm),其表面等离子体共振吸收峰较宽,最大吸收波长位于420nm;用室温硼氢化钠还原法得到的复合体系的吸收峰蓝移至409nm,且峰形较窄,Ag纳米粒子的平均粒径为8.7nm;低温NaBH4还原法所得体系吸收峰进一步蓝移至397nm,此时Ag纳米粒子粒径最小(3.5nm).将室温还原法所得Ag-PVA复合体系旋涂成膜,所得薄膜光滑、透明、均匀性好,该法适用于制备多层薄膜,以调控薄膜的厚度和光谱性质.将Ag-PVA复合体系与钛酸四丁酯(Ti(O_nBu)₄)的乙醇溶液交替旋涂得到Ag-PVA/TiO₂有机/无机复合薄膜.紫外-可见吸收光谱研究表明,随着Ag-PVA层数的增加,薄膜的表面等离子体共振吸收强度呈线性增加,但是TiO₂层数的增加对吸收光谱没有明显影响.Ag-PVA/TiO₂有机/无机复合薄膜将金属纳米粒子、有机高分子与无机半导体材料结合在一起,这种多层纳米结构在光电、催化功能薄膜等方面具有潜在的应用前景.     

Fused Triangulene Dimers: Facile Synthesis by Intramolecular Radical-Radical Coupling and Application for Near-Infrared Lasers

Large graphene-like molecules with four zigzag edges are ideal gain medium materials for organic near-infrared (NIR) lasers. However, synthesizing them becomes increasingly challenging as the molecular size increases. In this study, we introduce a new intramolecular radical-radical coupling approach and successfully synthesize two fused triangulene dimers ( 1 a / 1 b ) efficiently. X-ray crystallographic analysis of 1 a indicates that there is no intermolecular π-π stacking in the solid state. When the more soluble derivative 1 b is dispersed in polystyrene thin films, amplified spontaneous emission in the NIR region is observed. Using 1 b as the active gain material, we fabricate solution-processed distributed feedback lasers that exhibit a narrow emission linewidth at around 790 nm. The laser devices also exhibit low thresholds with high photostability. Our study provides a new synthetic strategy for extended nanographenes, which have diverse applications in electronics and photonics.     

Photostable NIR-II Pigments from Extended Rylenecarboximides

A series of near-infrared (NIR) organic absorbers, named FNs and FPs , have been obtained with absorption maxima from 870 nm to 1100 nm and thus falling into the attractive second near-infrared region (NIR-II). The synthesis of their extended aromatic cores utilized an initial aryl-amination between 4-aminonaphthalene-1,8-dicarboximide ( NMI-NH₂ ) or 9-aminoperylene-3,4-dicarboximide ( PMI-NH₂ ) with chloro-substituted 9,10-anthraquinones followed by a novel base-induced cyclodehydrogenation. A NIR-II pigment, compound FPP , was obtained through de-alkylation of a soluble precursor. The synthesis of this photostable pigment is high-yielding and avoids column chromatographic purification which is important for many applications.     

Rational design of a NIR-emitting Pd(II) sensor via oxidative cyclization to form a benzoxazole ring

By using the substituent effect to tune the palladium(II)-involved reactivity, a new probe is found to respond quantitatively to Pd(II). Unexpectedly, the probe gave an emission band in the desirable near-infrared (NIR) region (780 nm), thus providing the first NIR sensor for palladium detection.     

Optical gain from the open form of a photochromic molecule in the solid state

This work presents evidence for line-narrowing from the UV photoexcited open form of the photochromic molecule, indolinospiropyran (1',3'-dihydro-1',3',3'-trimethyl-6-nitrospiro [2H-1-benzopyran-2,2'-(2H)-indole]) in the solid state. The line-narrowing is attributable to amplified spontaneous emission induced by optical gain and assisted by the waveguiding within the organic film. Optical gain throughout a band as large as 28 nm, with a maximum gain coefficient of 5.6 cm(-1), is observed in the merocyanine emission region (660-730 nm). These results open the way to the realization of hybrid devices based on the coupling between photochromic behavior and stimulated emission from conjugated molecules, such as lasing optical memories, and lasers gated by optical molecular switches.     

Dramatic increases in the lifetime of the Er3+ ion in a molecular complex using a perfluorinated imidodiphosphinate sensitizing ligand

Dramatic increases in the luminescent lifetime of the Er3+ ion in a molecular complex have been observed by chelating the rare-earth ion with a perfluorinated imidodiphosphinate sensitizing ligand, F-tpip. For solution, powder, and evaporated thin films of Er(F-tpip)3, the average lifetimes of the 1530 nm emission band range between 150 and 220 mus, corresponding to a maximum 50-fold increase relative to the nonfluorinated analogue, Er(tpip)3. These are the longest reported lifetimes for the Er3+ ion in a simple organic chelate. These remarkable improvements in luminescence efficiency and excited-state lifetime represent a significant step forward in the design and fabrication of near-infrared (NIR)-emitting molecular devices for communications, sensing, and analytical detection.     

Ultrasmall near-infrared Ag2Se quantum dots with tunable fluorescence for in vivo imaging

A strategy is presented that involes coupling Na(2)SeO(3) reduction with the binding of silver ions and alanine in a quasi-biosystem to obtain ultrasmall, near-infrared Ag(2)Se quantum dots (QDs) with tunable fluorescence at 90 °C in aqueous solution. This strategy avoids high temperatures, high pressures, and organic solvents so that water-dispersible sub-3 nm Ag(2)Se QDs can be directly obtained. The photoluminescence of the Ag(2)Se QDs was size-dependent over a wavelength range from 700 to 820 nm, corresponding to sizes from 1.5 ± 0.4 to 2.4 ± 0.5 nm, with good monodispersity. The Ag(2)Se QDs are less cytotoxic than other nanomaterials used for similar applications. Furthermore, the NIR fluorescence of the Ag(2)Se QDs could penetrate through the abdominal cavity of a living nude mouse and could be detected on its back side, demonstrating the potential applications of these less toxic NIR Ag(2)Se QDs in bioimaging.     

NEAR-INFRARED DYES: Probe Development and Applications in Optical Molecular Imaging

The recent emergence of optical imaging has brought forth a unique challenge for chemists: development of new biocompatible dyes that fluoresce in the near-infrared (NIR) region for optimal use in biomedical applications. This review describes the synthesis of NIR dyes and the design of probes capable of noninvasively imaging molecular events in small animal models.     

Broad-band antireflection coating at near-infrared wavelengths by a breath figure

We prepared a porous thin film by spin-coating of a cellulose acetate butyrate (CAB) solution in tetrahydrofuran under a humid environment. Due to evaporative cooling during spin-coating, condensed water droplets were formed by a breath figure on the CAB solution, and these developed a porous structure after complete drying. By varying the solution concentration and rotating speeds, two distinct morphologies were generated: top and bottom layers with higher and lower porosities, respectively. We found that the two-layer porous film coated on glass exhibited low reflectance of less than 1% in the near-infrared (NIR) regime corresponding to wavelengths between 900 and 2200 nm. Since the porous structure was very uniform over a large area, the film could be easily employed for broad-band antireflection coating at NIR wavelengths.     

Spectroscopic studies of a near-infrared absorbing pH sensitive aminodienone-carbocyanine dye system

Synthetic red and near-infrared absorbing dyes may be used as probe molecules in a large number of applications. Dyes exhibiting spectral changes with hydrogen ion concentration are useful as pH probes. Those dyes which have their absorption and fluorescence maxima in the long wavelength region of the visible spectral region are specially valuable because of decreased interference and semiconductor laser applications. In this paper we have evaluated an aminodienone dyes 1 which demostrates pH dependent absorption and fluorescence spectra as well as solvent polarity dependence. In organic solvents the long wavelength absorption band of the dye is in the reduced interference region. The absorption maximum is at 535 nm in neutral or alkaline solutions in methanol. The absorption spectra undergo a strong bathochromic shift in the presence of acids (lambda(max) = 709 nm) with a concomitant change in the fluorescence spectra. This pH sensitive dye was found to be specially especially useful for organic solvents. The analytical utility of this and similar near-infrared absorbing dyes is discussed.     

Charge Transfer Metal-Organic Framework Containing Redox-Active TTF/NDI Units for Highly Efficient Near-Infrared Photothermal Conversion

Metal-organic frameworks (MOFs), as a class of new inorganic-organic hybrid crystal materials, could have important applications in near-infrared (NIR) photothermal conversion. Herein, a new charge-transfer MOF (Co-MOF) with mixed ligands of H₄TTFTB and bpmNDI incorporating redox-active tetrathiafulvalene/naphthalene diimide (TTF/NDI) units into one system is reported. Due to the presence of TTF/NDI oxidative and reductive couples, stable radicals can be observed in the MOF. In addition, charge transfer from the electron donor (TTF) to the acceptor (NDI) results in a broad absorption in the NIR region. The Co-MOF exhibited an efficient photothermal effect induced by irradiation with a NIR laser. Under the 808 nm laser (0.7 W cm⁻²) illumination, the temperature of the Co-MOF increased from room temperature to 201 °C in only 10 s. Furthermore, a series of polydimethylsiloxane (PDMS) films doped with trace amounts of Co-MOF showed efficient NIR photothermal conversion. When a Co-MOF@PDMS (0.6 wt %) film is irradiated by 808 nm laser with power of 0.5 W cm⁻², it′s temperature can reach a plateau at 62 °C from 20 °C within 100 s. Our experimental results from the Co-MOF@PDMS film demonstrate that the effectiveness and feasibility of the material is promising for photothermal applications.     

Formation of a perylenetetracarboxylic diimide network film by post electrochemical treatment

Perylenetetracarboxylic diimide (PDI) derivatives bearing two or four peripheral pyrrole pendants (PDI-nPy, n=2 or 4) are cross-linkable materials by electro/phototreatment. In this paper, we introduce a new posttreatment technique to produce an insoluble film. Unlike the common solution-phase electrochemical deposition, we first spin-coated PDI-nPy on an electrode and then electrotreated the coated surface in a monomer-free electrolyte solution. This method gives the film a smooth surface with no granules, while the common method induces a rough film with a lot of granules. The post electrochemical treatment also provides a merit of higher resolution in a patterning process on a specific metal electrode. As one of the applications, we carried out an electrochromic study on the posttreated PDI-4Py film. It turned purple (lambdamax=590 nm) and sky blue (lambdamax=797 nm) at 0 and -1.9 V vs Ag/Ag+, respectively. We believe this method will broaden the patterning concept with the desired film morphology and resolution using PDI on a specific electrode.     

Enhancement of Nonlinear Optical Scattering by Gold Nanoparticles through Aggregation-Induced Plasmon Coupling in the Near-Infrared

Gold nanoparticles (AuNPs) are regarded as promising building blocks in functional nanomaterials for sensing, drug delivery and catalysis. One remarkable property of these particles is the localized surface plasmon resonance (LSPR), which gives rise to augmented optical properties through local field enhancement. LSPR also influences the nonlinear optical properties of metal NPs (MNPs) making them potentially interesting candidates for fast, high resolution nonlinear optical imaging. In this work we characterize and discuss the wavelength dependence of the hyper-Rayleigh scattering (HRS) behavior of spherical gold nanoparticles (GNP) and gold nanorods (GNR) in solution, from 850 nm up to 1300 nm, covering the near-infrared (NIR) window relevant for deep tissue imaging. The high-resolution spectral data allows discriminating between HRS and two photon photoluminescence contributions. Upon particle aggregation, we measured very large enhancements (ca. 10⁴) of the HRS intensity in the NIR, which is explained by considering aggregation-induced plasmon coupling effects and local field enhancement. These results indicate that purposely designed coupled nanostructures could prove advantageous for nonlinear optical imaging and biosensing applications.     

Near-Infrared (>1000 nm) Light-Harvesters: Design,Synthesis and Applications

Organic molecules can absorb or emit light in UV, visible and infra-red (IR) region of solar radiation. Fifty percent of energy of solar radiation lies in the IR region of solar spectrum and extended π-conjugated molecules containing low optical band gap can absorb NIR radiations. Recently IR molecules have grabbed the attention of synthetic chemists. Although only few molecules have been reported so far such as derivative of BODIPY, naphthalimide, porphyrins, perylene, BBT etc., they have shown highest absorbing capacity towards greater than 1100 nm. These compounds have potential applications in different fields, such as for biomedical and optoelectronic applications. In this review, we present different classes of light-harvesters with harvesting range above 1000 nm.     

Narrowband Near-Infrared Multiple-Resonance Thermally Activated Delayed Fluorescence Emitters towards High-Performance and Stable Organic Light-Emitting Diodes

Multiple-resonance thermally activated delayed fluorescence (MR-TADF) materials are highly coveted for their high efficiency and narrowband emission in organic light-emitting diodes (OLEDs). Nevertheless, the development of near-infrared (NIR) MR-TADF emitters remains a formidable challenge. In this study, we design two new NIR MR-TADF emitters, PXZ−R−BN and BCz−R−BN, by embedding 10H-phenoxazine (PXZ) and 7H-dibenzo[c,g]carbazole (BCz) fragments to increase the electron-donating ability or extending π-conjugation on the framework of para-boron fusing polycyclic aromatic hydrocarbons (PAHs). Both compounds emit in the NIR region, with a full-width at half-maximum (FWHM) of 49 nm (0.13 eV) for PXZ−R−BN and 43 nm (0.11 eV) for BCz−R−BN in toluene. To sensitize the two NIR MR-TADF emitters in OLEDs, a new platinum complex, Pt-1, is designed as a sensitizer. The PXZ−R−BN-based sensitized OLEDs achieve a maximum external quantum efficiency (EQE_max) of nearly 30 % with an emission band at 693 nm, and exceptional long operational stability with an LT₉₇ (time to 97 % of the initial luminance) value of 39084 h at an initial radiance of 1000 mW sr⁻¹ m⁻². The BCz−R−BN-based OLEDs reach EQE_max values of 24.2 % with an emission band at 713 nm, which sets a record value for NIR OLEDs with emission bands beyond 700 nm.     

Autocatalytic polymerization of selenium/polypyrrole nanocomposites as functional theranostic agents for multi-spectral photoacoustic imaging and photothermal therapy of tumor

The synchronization of diagnosis and treatment is a new trend in cancer treatment. Photoacoustic imaging (PAI) and photothermal therapy (PTT) are recognized as one of the perfect combinations. The autocatalytic polymerization of selenium/polypyrrole (Se@PPy) nanocomposites with a wide-absorption band at near-infrared region (NIR, 800 nm) has been developed in this paper. The wide optical absorption characteristics enable Se@PPy nanocomposites to achieve multi-spectral PAI. Ex vivo experiments show desirable photoacoustic ability of the Se@PPy nanocomposites at wavelengths ranging from 700 nm to 900 nm, which is better than that of commercial indocyanine green (ICG). Se@PPy nanocomposites have high photothermal conversion efficiency up to 36.3% as well as excellent photo-thermal stability. In vitro cytotoxicity test demonstrates that the Se@PPy nanocomposites have good bio-safety. Furthermore, the feasibility of Se@PPy nanocomposites for enhancing multi-spectral PAI guided PTT was verified on 4T1 tumor-bearing nude mice. Our results indicate that Se@PPy nanocomposites could be used as an effective theranostic agent for near-infrared light-mediated PAI and PTT of tumor.     

近红外光谱在蛋白质和含酰胺基团聚合物研究中的应用*

近红外光谱(near-infrared spectroscopy,NIR)是一种常用的无损表征手段,但谱带强度弱、交叠情况严重等缺点局限了它的应用范围。本文介绍了几种常见的改善近红外光谱技术不足的方法,如二阶导数法、二维相关光谱法和化学计量法等,并举例阐述了近红外光谱在蛋白质和含酰胺基团聚合物的结构和含量等方面的应用。这些方法对近红外光谱的定性定量分析起了很好的辅助作用,有效地拓宽了近红外光谱技术的应用领域。     

Synthesis of Bioctacene-Incorporated Nanographene with Near-Infrared Chiroptical Properties

We report the synthesis of a hexabenzoperihexacene (HBPH) with two incorporated octacene substructures, which was unambiguously characterized by single-crystal X-ray analysis. The theoretical isomerization barrier of the (P,P)-/(P,M)-forms was estimated to be 38.4 kcal mol⁻¹, and resolution was achieved by chiral HPLC. Notably, the enantiomers exhibited opposite circular dichroism responses up to the near-infrared (NIR) region (830 nm) with a high g_abs value of 0.017 at 616 nm. Moreover, HBPH demonstrated NIR emission with a maximum at 798 nm and an absolute PLQY of 41 %. The excited-state photophysical properties of HBPH were investigated by ultrafast transient absorption spectroscopy, revealing an intriguing feature that was attributed to the rotational and/or conformational dynamics of HBPH after excitation. These results provide new insight into the design of chiral nanographene with NIR optical properties for potential chiroptical applications.     

Stimuli-responsive organic chromic materials with near-infrared emission

Some organic chromic materials responding to external stimuli, mainly to mechanical forces, with a near-infrared (NIR) emission are discussed. In line with reported cases, there is a conclusion that subtle changes in conformations and packing modes are the primary elements contributing to the optical properties changes.