Visualization of pulmonary clearance mechanisms via noninvasive optical imaging validated by near-infrared flow cytometry

In vivo optical imaging with near-infrared (NIR) probes is an established method of diagnostics in preclinical and clinical studies. However, the specificities of these probes are difficult to validate ex vivo due to the lack of NIR flow cytometry. To address this limitation, we modified a flow cytometer to include an additional NIR channel using a 752 nm laser line. The flow cytometry system was tested using NIR microspheres and cell lines labeled with a combination of visible range and NIR fluorescent dyes. The approach was verified in vivo in mice evaluated for immune response in lungs after intratracheal delivery of the NIR contrast agent. Flow cytometry of cells obtained from the lung bronchoalveolar lavage demonstrated that the NIR dye was taken up by pulmonary macrophages as early as 4-h post-injection. This combination of optical imaging with NIR flow cytometry extends the capability of imaging and enables complementation of in vivo imaging with cell-specific studies.

Turn-on fluorescent sensing of glutathione S-transferase at near-infrared region based on FRET between gold nanoclusters and gold nanorods

A fluorescence resonance energy transfer (FRET) method based on gold nanoclusters capped glutathione (AuNCs@GSH) and amine-terminated gold nanorods (AuNRs) is designed for turn-on and near-infrared region (NIR) sensing of glutathione S-transferase (GST). The absorption band of AuNRs is tuned carefully to maximize the spectra overlap and enhance the efficiency of FRET. The FRET from multiple AuNCs to single AuNR quenches about 70% fluorescence emission of AuNCs. After GST is added, the strong specific interaction of GSH-GST can replace the AuNCs@GSH from AuNRs, FRET based on electrostatic interaction between AuNCs@GSH and AuNRs is switched off. Thus, emission enhancement of AuNCs@GSH is observed. The fluorescent enhancement is linearly with the increasing GST concentration over the range of 2-100 nM GST and the limit of detection for GST is about 1.5 nM.

Review of short-wave infrared spectroscopy and imaging methods for biological tissue characterization

We present a review of short-wave infrared (SWIR, defined here as ∼1000 to 2000 nm) spectroscopy and imaging techniques for biological tissue optical property characterization. Studies indicate notable SWIR absorption features of tissue constituents including water (near 1150, 1450, and 1900 nm), lipids (near 1040, 1200, 1400, and 1700 nm), and collagen (near 1200 and 1500 nm) that are much more prominent than corresponding features observed in the visible and near-infrared (VIS-NIR, defined here as ∼400 to 1000 nm). Furthermore, the wavelength dependence of the scattering coefficient has been observed to follow a power-law decay from the VIS-NIR to the SWIR region. Thus, the magnitude of tissue scattering is lower at SWIR wavelengths than that observed at VIS or NIR wavelengths, potentially enabling increased penetration depth of incident light at SWIR wavelengths that are not highly absorbed by the aforementioned chromophores. These aspects of SWIR suggest that the tissue spectroscopy and imaging in this range of wavelengths have the potential to provide enhanced sensitivity (relative to VIS-NIR measurements) to chromophores such as water and lipids, thereby helping to characterize changes in the concentrations of these chromophores due to conditions such as atherosclerotic plaque, breast cancer, and burns.

Macroscopic-imaging technique for subsurface quantification of near-infrared markers during surgery

Obtaining accurate quantitative information on the concentration and distribution of fluorescent markers lying at a depth below the surface of optically turbid media, such as tissue, is a significant challenge. Here, we introduce a fluorescence reconstruction technique based on a diffusion light transport model that can be used during surgery, including guiding resection of brain tumors, for depth-resolved quantitative imaging of near-infrared fluorescent markers. Hyperspectral fluorescence images are used to compute a topographic map of the fluorophore distribution, which yields structural and optical constraints for a three-dimensional subsequent hyperspectral diffuse fluorescence reconstruction algorithm. Using the model fluorophore Alexa Fluor 647 and brain-like tissue phantoms, the technique yielded estimates of fluorophore concentration within ±25% of the true value to depths of 5 to 9 mm, depending on the concentration. The approach is practical for integration into a neurosurgical fluorescence microscope and has potential to further extend fluorescence-guided resection using objective and quantified metrics of the presence of residual tumor tissue.

Magneto-optical nanoparticles for cyclic magnetomotive photoacoustic imaging

Photoacoustic imaging has emerged as a highly promising tool to visualize molecular events with deep tissue penetration. Like most other modalities, however, image contrast under in vivo conditions is far from optimal due to background signals from tissue. Using iron oxide-gold core-shell nanoparticles, we have previously demonstrated the concept of magnetomotive photoacoustic (mmPA) imaging, which is capable of dramatically reducing the influence of background signals and producing high-contrast molecular images. Here, we report two significant advances toward clinical translation of this technology. First, we introduce a new class of compact, uniform, magneto-optically coupled core-shell nanoparticles, prepared through localized copolymerization of polypyrrole (PPy) on an iron oxide nanoparticle surface. The resulting iron oxide-PPy nanoparticles feature high colloidal stability and solve the photoinstability and small-scale synthesis problems previously encountered by the gold coating approach. In parallel, we have developed a new generation of mmPA featuring cyclic magnetic motion and ultrasound speckle tracking (USST), whose imaging capture frame rate is several hundred times faster than the photoacoustic speckle tracking (PAST) method we demonstrated previously. These advances enable robust artifact elimination caused by physiologic motions and demonstrate the application of the mmPA technology for in vivo sensitive tumor imaging.

(formula particles): From lab investigation to pilot-scale extraction process

Background:

Extraction process of dried flowers of formula particles should be investigated from lab investigation to pilot-scale because of good water absorbing capacity and obscure active pharmaceutical ingredients (API) dissolution.

Objective:

Reliable analysis of on-line near-infrared (NIR) technique and novel application in fascinating modern, traditional Chinese medicine production (formula particles) was proved.

Materials and Methods:

The extraction process of Sophora japonica L. (formula particles) was used as an example, the rutin was regarded as API. On-line NIR technology was used to monitor the variation of rutin in the extraction process. High-performance liquid chromatography (HPLC) was used as a reference method to determine the content of rutin during the extraction process. The sample set was selected by Kennard-Stone (KS) algorithm. Different pretreatment methods were compared. The synergy interval partial least square (SiPLS) algorithm was applied. Chemometrics indicators and multivariate detection limits method were mutually used to assess the model.

Results:

According to both errors α (0.05) and β (0.05), rutin content could be detected by on-line NIR, which was more than 0.181 mg/mL.

Conclusions:

This work demonstrated the feasibility of NIR for on-line determination of rutin in the pilot-scale extraction process of S. japonica. L. It provided technical support for the NIR application in the extraction process of formula particles.

Transparent organic upconversion devices for near-infrared sensing

Transparent organic upconversion devices are shown in a night-vision demonstration of a real object under near-infrared (NIR) illumination in the dark. An extraordinarily high current gain - reflecting the on-off switching effect - greater than 15 000 at a driving voltage of 3 V is demonstrated, indicating the high sensitivity to NIR light and potential of using the proposed upconverter in practical applications. A maximum luminance exceeding 1500 cd m(-2) at 7 V is achieved. Unlike previous studies, where 2D aperture projection is reported, the current study shows 3D images of real objects under NIR illumination in the dark.

Bioinspired near-infrared-excited sensing platform for in vitro antioxidant capacity assay based on upconversion nanoparticles and a dopamine-melanin hybrid system

A novel core-shell structure based on upconversion fluorescent nanoparticles (UCNPs) and dopamine-melanin has been developed for evaluation of the antioxidant capacity of biological fluids. In this approach, dopamine-melanin nanoshells facilely formed on the surface of UCNPs act as ultraefficient quenchers for upconversion fluorescence, contributing to a photoinduced electron-transfer mechanism. This spontaneous oxidative polymerization of the dopamine-induced quenching effect could be effectively prevented by the presence of various antioxidants (typically biothiols, ascorbic acid (Vitamin C), and Trolox). The chemical response of the UCNPs@dopamine-melanin hybrid system exhibited great selectivity and sensitivity toward antioxidants relative to other compounds at 100-fold higher concentration. A satisfactory correlation was established between the ratio of the "anti-quenching" fluorescence intensity and the concentration of antioxidants. Besides the response of the upconversion fluorescence signal, a specific evaluation process for antioxidants could be visualized by the color change from colorless to dark gray accompanied by the spontaneous oxidation of dopamine. The near-infrared (NIR)-excited UCNP-based antioxidant capacity assay platform was further used to evaluate the antioxidant capacity of cell extracts and human plasma, and satisfactory sensitivity, repeatability, and recovery rate were obtained. This approach features easy preparation, fluorescence/visual dual mode detection, high specificity to antioxidants, and enhanced sensitivity with NIR excitation, showing great potential for screening and quantitative evaluation of antioxidants in biological systems.

Tunable ultrasmall visible-to-extended near-infrared emitting silver sulfide quantum dots for integrin-targeted cancer imaging

The large size of many near-infrared (NIR) fluorescent nanoparticles prevents rapid extravasation from blood vessels and subsequent diffusion to tumors. This confines in vivo uptake to the peritumoral space and results in high liver retention. In this study, we developed a viscosity modulated approach to synthesize ultrasmall silver sulfide quantum dots (QDs) with distinct tunable light emission from 500 to 1200 nm and a QD core diameter between 1.5 and 9 nm. Conjugation of a tumor-avid cyclic pentapeptide (Arg-Gly-Asp-DPhe-Lys) resulted in monodisperse, water-soluble QDs (hydrodynamic diameter < 10 nm) without loss of the peptide's high binding affinity to tumor-associated integrins (KI = 1.8 nM/peptide). Fluorescence and electron microscopy showed that selective integrin-mediated internalization was observed only in cancer cells treated with the peptide-labeled QDs, demonstrating that the unlabeled hydrophilic nanoparticles exhibit characteristics of negatively charged fluorescent dye molecules, which typically do not internalize in cells. The biodistribution profiles of intravenously administered QDs in different mouse models of cancer reveal an exceptionally high tumor-to-liver uptake ratio, suggesting that the small sized QDs evaded conventional opsonization and subsequent high uptake in the liver and spleen. The seamless tunability of the QDs over a wide spectral range with only a small increase in size, as well as the ease of labeling the bright and noncytotoxic QDs with biomolecules, provides a platform for multiplexing information, tracking the trafficking of single molecules in cells, and selectively targeting disease biomarkers in living organisms without premature QD opsonization in circulating blood.

Titania coated upconversion nanoparticles for near-infrared light triggered photodynamic therapy

Because of the limited penetration depth of visible light that generally excites most of the available photosensitizers (PSs), conventional photodynamic therapy (PDT) is limited to the treatment of superficial and flat lesions. Recently, the application of deep penetrating near-infrared (NIR) light excitable upconversion nanoparticles (UCNs) in conjunction with PDT has shown to have clear potential in the treatment of solid tumors due to its ability to penetrate thick tissue. However, various constructs developed so far have certain limitations such as poor or unstable PS loading, reducing their therapeutic efficacy and limiting their application to solution or cell-based studies. In this work, we present a method to fabricate uniform core-shell structured nanoconstruct with a thin layer of photocatalyst or PS-titanium dioxide (TiO2) stably coated on individual UCN core. Our design allows controllable and highly reproducible PS loading, preventing any leakage of PS compared to previously developed nanoconstructs, thus ensuring repeatable PDT results. Further surface modification of the developed nanoconstructs with polyethylene glycol (PEG) rendered them biocompatible, demonstrating good therapeutic efficacy both in vitro and in vivo.

A silica-gold-silica nanocomposite for photothermal therapy in the near-infrared region

The focus of this work was to study the photothermal effect of a silica-gold-silica nanocomposite in the near-infrared (NIR) region. The NIR region is considered a biological window because living cells and tissues have low light scattering and adsorption in this region. Both a laser source and a tungsten lamp source were used in this study. The critical parameters for photothermal efficiency, including nancomposite concentration and irradiation time, were evaluated. The penetration of the nanocomposites into mammalian cells was also investigated. With laser irradiation, the nanocomposite showed a significant photothermal effect in the NIR region. The maximal temperature that the nanocomposites could reach was 51.9 °C. Vybrant assays showed that 5 min of laser irradiation along with the nanocomposite caused target cell death through both apoptosis (59%) and necrosis (31%), while controls showed minimal effects. The nanocomposite may be a potential light-absorbing agent for NIR fluorescence-guided photothermal therapy.

Near-infrared spectroscopy-based microcirculatory assessment in acute atrial fibrillation

Near-infrared spectroscopy is a means of assessing microcirculatory function, but has not been studied in atrial fibrillation (AF). We evaluated the effect of acute AF on thenar eminence near-infrared spectroscopy-derived microcirculatory variables. Stable patients presenting to the emergency department with acute onset AF underwent dynamic near-infrared spectroscopy assessment with a three minute vascular occlusion test (VOT). This was repeated after cardioversion to sinus rhythm (SR). Each assessment included baseline tissue oxygen saturation (StO2), slope of StO2 decrease during VOT, slope of StO2 increase post VOT, minimum and maximum StO2, amplitude of StO2 response and post-ischaemic hyperperfusion. Pre and post cardioversion values were compared by Wilcoxon signed-rank test. Twelve participants (seven male, five female) with a median age of 63 years (interquartile range 52 to 70 years) were enrolled. Median baseline StO2 was 74% before and 77% after cardioversion (P=0.03). The median slope of StO2 decrease during VOT was -0.19%/second and -0.16%/second (P=0.018) and the median slope of StO2 increase post VOT was 3.03%/second and 2.56%/second (P=0.002), pre and post cardioversion, respectively. Minimum StO2 was lower (39% versus 52%, P=0.002) and the amplitude of StO2 response greater (49% versus 40%, P=0.005) in AF, but there was no significant difference in maximum StO2 or the degree of reperfusion hyperaemia. In summary, baseline and minimum StO2 were lower with a greater ischaemic decrease in StO2 during AF, reflecting reduced tissue perfusion, compared with sinus rhythm. Recovery after ischaemia was higher in AF, suggesting normalisation of capillary recruitment during ischaemia.

Passive tumor targeting and imaging by using mercaptosuccinic acid-coated near-infrared quantum dots

In this paper, we demonstrate the preparation of monodispersed quantum dots (QDs) as near-infrared (NIR) optical probes for in vivo pancreatic cancer targeting and imaging. The design of these luminescent probes involves functionalizing NIR QDs with ligand mercaptosuccinic acid (MSA), which targets the tumor site by enhanced permeability and retention effect. The colloidal and optical stability of the QDs can be maintained for >1 week. In vivo optical imaging studies in nude mice bearing pancreatic tumor show that the probes accumulate at tumor sites for >2.5 hours following intravenous injection of the functionalized NIR QDs. Tumor-labeling studies showed no evidence of harmful effects on the treated animals, even at a dose as high a ~50 mg/kg. These results demonstrate that the engineered MSA-functionalized QDs can serve as a diagnostic platform for early detection of cancer, as well as in image-guided precise surgical resection of tumors.

Fast self-healing of graphene oxide-hectorite clay-poly(N,N-dimethylacrylamide) hybrid hydrogels realized by near-infrared irradiation

Self-healing hydrogels were proposed to be used as biomaterials, because of the capability of spontaneously healing injury, but most of the reported self-healing hydrogels do not possess high mechanical strength and fast self-healing at the same time. Herein, we prepared graphene oxide (GO)-hectorite clay-poly(N,N-dimethylacrylamide) (PDMAA) hybrid hydrogels with enhanced mechanical properties and fast self-healing capability realized by near-infrared (NIR) irradiation. The physical cross-linking between clay sheets and PDMAA chains provided the hydrogel with mechanical strength to maintain its stability in shape and architecture. GO sheets in the hybrid hydrogels acted as not only a collaborative cross-linking agent but also as a NIR absorber to absorb the NIR irradiation energy and transform it to thermal energy rapidly and efficiently, resulting in a rapid temperature increase of the GO containing gels. The chain mutual diffusion and the reformation of physical cross-linking occurred more quickly at higher temperature; consequently, the damaged hydrogel was almost completely recovered in a few minutes upon irradiation. We also demonstrated a potential application of the hybrid hydrogel as a self-healing surgical dressing.

A photostable near-infrared fluorescent tracker with pH-independent specificity to lysosomes for long time and multicolor imaging

A new boron-dipyrromethene-based lysosome tracker, Lyso-NIR, is facilely synthesized. Besides the intensive near-infrared (NIR) fluorescence and high photostability, Lyso-NIR shows the capability to stably localize in lysosomes, which is independent of the local pH. Lyso-NIR does not have the problematic alkalization effect suffered by the commonly used lysotrackers; thus, it shows ignorable cytotoxicity and slightly affects normal physiological functions of lysosomes. The above advantages of Lyso-NIR make it feasible to track lysosomes' dynamic changes in a relatively long time during the full cellular processes such as apoptosis, heavy metal stimulation, and endocytosis, as is demonstrated in this work. Moreover, Lyso-NIR's narrow NIR emission at 740 nm with a full width at half-maximum smaller than 50 nm makes it easy to avoid the crosstalk with the emissions from other common fluorescent probes, which strengthens Lyso-NIR's competitiveness as a standard lysosome tracker for multicolor bioimaging.

A near-infrared dithieno[2,3-a:3',2'-c]phenazine-based organic co-sensitizer for highly efficient and stable quasi-solid-state dye-sensitized solar cells

A novel near-infrared (NIR) organic sensitizer FNE53 with a strong electron-withdrawing unit, dithieno[2,3-a:3',2'-c]phenazine, has been designed and synthesized for quasi-solid-state dye-sensitized solar cells (DSSCs). By simply fusing the two thiophene rings on quinoxaline unit in sensitizer FNE48, the intramolecular charge transfer (ICT) band bathochromically shifts from 542 nm for FNE48 to 629 nm for FNE53 in toluene solution. The absorption spectrum of sensitizer FNE53 covers the whole visible region and extends to the NIR region, which exhibits complementary absorption profile to another organic dye FNE46 based on quinoxaline. When FNE46 and FNE53 are used as cosensitizers for metal-free cocktail-type quasi-solid-state DSSCs, sensitizer FNE53 not only extends the photoresponse range but also suppresses the intermolecular interactions among the dye molecules. Therefore, the cocktail-type quasi-solid-state DSSC displays much higher IPCE value compared with that for the DSSC sensitizer based on FNE53 and a broader IPCE response in comparison to that for the DSSC sensitizers based on FNE46, respectively. After the molar ratio between the two cocktail dyes is optimized, the highest energy conversion efficiency of 8.04% is achieved in a metal-free quasi-solid-state DSSC cosensitized with FNE46 and FNE53, which exhibits good long-term stability after continuous light soaking for 1000 h.

Black phosphorus photodetector for multispectral, high-resolution imaging

Black phosphorus is a layered semiconductor that is intensely researched in view of applications in optoelectronics. In this letter, we investigate a multilayer black phosphorus photodetector that is capable of acquiring high-contrast (V > 0.9) images both in the visible (λVIS = 532 nm) as well as in the infrared (λIR = 1550 nm) spectral regime. In a first step, by using photocurrent microscopy, we map the active area of the device and we characterize responsivity and gain. In a second step, by deploying the black phosphorus device as a point-like detector in a confocal microsope setup, we acquire diffraction-limited optical images with submicron resolution. The results demonstrate the usefulness of black phosphorus as an optoelectronic material for hyperspectral imaging applications.

Aggregation-induced near-infrared absorption of squaraine dye in an albumin nanocomplex for photoacoustic tomography in vivo

Photoacoustic tomography (PAT) is a newly emerging noninvasive imaging modality that could be further enhanced using near-infrared (NIR)-absorbing materials as contrast agents. To date, the most extensively studied photoacoustic imaging agents are inorganic nanomaterials because organic materials with NIR-absorption capabilities are limited. In this study, a NIR-absorbing nanocomplex composed of a squaraine dye (SQ) and albumin was prepared based on the aggregation-induced NIR absorption of SQ. Through aggregation, the absorption spectrum of SQ was widened from the visible-light region to the NIR region, which facilitated photoacoustic signal generation in the tissue-transparent NIR optical window (700-900 nm). Blood analysis and histology measurements revealed that the nanocomplex can be used for PAT applications in vivo without obvious toxicity to living mice.

Simultaneous multiple wavelength upconversion in a core-shell nanoparticle for enhanced near infrared light harvesting in a dye-sensitized solar cell

The efficiency of most photovoltaic devices is severely limited by near-infrared (NIR) transmission losses. To alleviate this limitation, a new type of colloidal upconversion nanoparticles (UCNPs), hexagonal core-shell-structured β-NaYbF4:Er(3+)(2%)/NaYF4:Nd(3+)(30%), is developed and explored in this work as an NIR energy relay material for dye-sensitized solar cells (DSSCs). These UCNPs are able to harvest light energy in multiple NIR regions, and subsequently convert the absorbed energy into visible light where the DSSCs strongly absorb. The NIR-insensitive DSSCs show compelling photocurrent increases through binary upconversion under NIR light illumination either at 785 or 980 nm, substantiating efficient energy relay by these UCNPs. The overall conversion efficiency of the DSSCs was improved with the introduction of UCNPs under simulated AM 1.5 solar irradiation.

Near-infrared emitting fluorescent BODIPY nanovesicles for in vivo molecular imaging and drug delivery

Near-infrared fluorescent nanovesicles were prepared by self-assembly of block copolymer hydrophilic poly(ethylene glycol) boron-dipyrromethenes in aqueous solution. The fluorescence enhancement induced by dissociation of nanovesicles could be used as a smart imaging and diagnostic tool. This nanovesicle could encapsulate the antitumor drug, and provide a powerful platform for imaging-guided tumor-specific drug delivery and therapy.

Synthesis of a quantum nanocrystal-gold nanoshell complex for near-infrared generated fluorescence and photothermal decay of luminescence

Multifunction nanoparticle complexes have previously been developed to aid physicians in both diagnosis and treatment of cancerous tissue. Here, we designed a nanoparticle complex structure that consists of a plasmonically active hollow gold nanoshell core surrounded by photoluminescent quantum nanocrystals (QNs) in the form of PbS encapsulated by a silica layer. There are three main design variables including HGN synthesis and optical tuning, formation of the silica layer on the hollow gold nanoshell surface, and fabrication and photoluminescence tuning of PbS quantum nanocrystals. The hollow gold nanoshells were deliberately designed to function in the optical regimes that maximize tissue transmissivity (800 nm) and minimize tissue absorption (1100 nm). Secondly, several chemical ligands were tested such as (3-mercaptopropyl)trimethoxysilane and mercaptoundecanoic acid for controlled growth of the silica layer. Last, PbS QNs were synthesized and optimized with various capping agents, where the nanocrystals excited at the same wavelength were used to activate the photothermal properties of the hollow gold nanoshells. Upon irradiation of the complex with a lower power 800 nm laser, the nanocrystals luminesce at 1100 nm. At ablative temperatures the intrinsic luminescent properties of the QNs are altered and the luminescent output is significantly reduced (>70%). While this paper focuses on synthesis and optimization of the QN-HGN complex, in the future we believe that this novel particle complex design may have the potential to serve as a triple theranostic agent, which will aid satellite tumor localization, photothermal treatment, and ablative confirmation.

The S28H mutation on mNeptune generates a brighter near-infrared monomeric fluorescent protein with improved quantum yield and pH-stability

For living deep-tissue imaging, the optical window favorable for light penetration is in near-infrared wavelengths, which requires fluorescent proteins with emission spectra in the near-infrared region. Here, we report that a single mutant Ser28His of mNeptune with a near-infrared (≥650 nm) emission maxima of 652 nm is found to improve the brightness, photostability, and pH stability when compared with its parental protein mNeptune, while it remains as a monomer, demonstrating that there is still plenty of room to improve the performance of the existing near infrared fluorescence proteins by directed evolution.

Near-infrared-emitting two-dimensional codes based on lattice-strained core/(doped) shell quantum dots with long fluorescence lifetime

Lattice-strained CdTe/CdS:Cu quantum dots (QDs) with a widely tunable near-infrared (NIR) fluorescence emission spectrum (700-910 nm) and long lifetime (up to 1 μs) are synthesized. Based on the multiemission and multi-lifetime of the well-defined QDs, NIR-emitting two-dimensional (2D) codes are achieved by embedding as-prepared QDs into agarose beads. This provides a new strategy for fluorescent 2D codes.

Semiconducting carbon nanotube aerogel bulk heterojunction solar cells

Using a novel two-step fabrication scheme, we create highly semiconducting-enriched single-walled carbon nanotube (sSWNT) bulk heterojunctions (BHJs) by first creating highly porous interconnected sSWNT aerogels (sSWNT-AEROs), followed by back-filling the pores with [6,6]-phenyl-C(71)-butyric acid methyl ester (PC(71)BM). We demonstrate sSWNT-AERO structures with density as low as 2.5 mg cm(-3), porosity as high as 99.8%, and diameter of sSWNT fibers ≤ 10 nm. Upon spin coating with PC(71)BM, the resulting sSWNT-AERO-PC(71)BM nanocomposites exhibit highly quenched sSWNT photoluminescence, which is attributed to the large interfacial area between the sSWNT and PC(71)BM phases, and an appropriate sSWNT fiber diameter that matches the inter-sSWNT exciton migration length. Employing the sSWNT-AERO-PC(71)BM BHJ structure, we report optimized solar cells with a power conversion efficiency of 1.7%, which is exceptional among polymer-like solar cells in which sSWNTs are designed to replace either the polymer or fullerene component. A fairly balanced photocurrent is achieved with 36% peak external quantum efficiency (EQE) in the visible and 19% peak EQE in the near-infrared where sSWNTs serve as electron donors and photoabsorbers. Our results prove the effectiveness of this new method in controlling the sSWNT morphology in BHJ structures, suggesting a promising route towards highly efficient sSWNT photoabsorbing solar cells.

Encapsulated Fe3O4 /Ag complexed cores in hollow gold nanoshells for enhanced theranostic magnetic resonance imaging and photothermal therapy

Designed and fabrication of a novel magnetic hollow gold nanoshell complexes that incorporates iron oxide nanoparticles in the hollow interior. The combined effect of the smaller IONPs improved the overall magnetic properties of the design and MRI contrast capability. The overall complex could be synthesized in the range of 60-80 nm in diameter while still having a plasmonic peak in the near infrared region.

Size-tunable and monodisperse Tm³⁺/Gd³⁺-doped hexagonal NaYbF₄ nanoparticles with engineered efficient near infrared-to-near infrared upconversion for in vivo imaging

Hexagonal NaYbF4:Tm(3+) upconversion nanoparticles hold promise for use in high contrast near-infrared-to-near-infrared (NIR-to-NIR) in vitro and in vivo bioimaging. However, significant hurdles remain in their preparation and control of their morphology and size, as well as in enhancement of their upconversion efficiency. Here, we describe a systematic approach to produce highly controlled hexagonal NaYbF4:Tm(3+) nanoparticles with superior upconversion. We found that doping appropriate concentrations of trivalent gadolinium (Gd(3+)) can convert NaYbF4:Tm(3+) 0.5% nanoparticles with cubic phase and irregular shape into highly monodisperse NaYbF4:Tm(3+) 0.5% nanoplates or nanospheres in a pure hexagonal-phase and of tunable size. The intensity and the lifetime of the upconverted NIR luminescence at 800 nm exhibit a direct dependence on the size distribution of the resulting nanoparticles, being ascribed to the varied surface-to-volume ratios determined by the different nanoparticle size. Epitaxial growth of a thin NaYF4 shell layer of ∼2 nm on the ∼22 nm core of hexagonal NaYbF4:Gd(3+) 30%/Tm(3+) 0.5% nanoparticles resulted in a dramatic 350 fold NIR upconversion efficiency enhancement, because of effective suppression of surface-related quenching mechanisms. In vivo NIR-to-NIR upconversion imaging was demonstrated using a dispersion of phospholipid-polyethylene glycol (DSPE-PEG)-coated core/shell nanoparticles in phosphate buffered saline.

Directed evolution of a far-red fluorescent rhodopsin

Microbial rhodopsins are a diverse group of photoactive transmembrane proteins found in all three domains of life. A member of this protein family, Archaerhodopsin-3 (Arch) of halobacterium Halorubrum sodomense, was recently shown to function as a fluorescent indicator of membrane potential when expressed in mammalian neurons. Arch fluorescence, however, is very dim and is not optimal for applications in live-cell imaging. We used directed evolution to identify mutations that dramatically improve the absolute brightness of Arch, as confirmed biochemically and with live-cell imaging (in Escherichia coli and human embryonic kidney 293 cells). In some fluorescent Arch variants, the pK(a) of the protonated Schiff-base linkage to retinal is near neutral pH, a useful feature for voltage-sensing applications. These bright Arch variants enable labeling of biological membranes in the far-red/infrared and exhibit the furthest red-shifted fluorescence emission thus far reported for a fluorescent protein (maximal excitation/emission at ∼ 620 nm/730 nm).

Photostimulable near-infrared persistent luminescent nanoprobes for ultrasensitive and longitudinal deep-tissue bio-imaging

In vivo fluorescence imaging suffers from suboptimal signal-to-noise ratio and shallow detection depth, which is caused by the strong tissue autofluorescence under constant external excitation and the scattering and absorption of short-wavelength light in tissues. Here we address these limitations by using a novel type of optical nanoprobes, photostimulable LiGa₅O₈:Cr³⁺ near-infrared (NIR) persistent luminescence nanoparticles, which, with very-long-lasting NIR persistent luminescence and unique photo-stimulated persistent luminescence (PSPL) capability, allow optical imaging to be performed in an excitation-free and hence, autofluorescence-free manner. LiGa₅O₈:Cr³⁺ nanoparticles pre-charged by ultraviolet light can be repeatedly (>20 times) stimulated in vivo, even in deep tissues, by short-illumination (~15 seconds) with a white light-emitting-diode flashlight, giving rise to multiple NIR PSPL that expands the tracking window from several hours to more than 10 days. Our studies reveal promising potential of these nanoprobes in cell tracking and tumor targeting, exhibiting exceptional sensitivity and penetration that far exceed those afforded by conventional fluorescence imaging.

Multispectral measurement of contrast in tissue-mimicking phantoms in near-infrared spectral range of 650 to 1600 nm

In order to identify the optimal imaging conditions for the highest spatial contrast in biological tissue, we explored the properties of a tissue-mimicking phantom as a function of the wavelengths in a broad range of near-infrared spectra (650 to 1600 nm). Our customized multispectral hardware, which featured a scanning transmission microscope and imaging spectrographs equipped with silicon and InGaAs charge-coupled diode array detectors, allowed for direct comparison of the Michelson contrast obtained from a phantom composed of a honeycomb grid, Intralipid, and India ink. The measured contrast depended on the size of the grid, luminance, and the wavelength of measurements. We demonstrated that at low thickness of the phantom, a reasonable contrast of the objects can be achieved at any wavelength between 700 and 1400 nm and between 1500 and 1600 nm. At larger thicknesses, such contrast can be achieved mostly between 1200 and 1350 nm. These results suggest that distinguishing biological features in deep tissue and developing contrast agents for in vivo may benefit from imaging in this spectral range.

In vivo imaging of membrane type-1 matrix metalloproteinase with a novel activatable near-infrared fluorescence probe

Membrane type-1 matrix metalloproteinase (MT1-MMP) is a protease activating MMP-2 that mediates cleavage of extracellular matrix components and plays pivotal roles in tumor migration, invasion and metastasis. Because in vivo noninvasive imaging of MT1-MMP would be useful for tumor diagnosis, we developed a novel near-infrared (NIR) fluorescence probe that can be activated following interaction with MT1-MMP in vivo. MT1-hIC7L is an activatable fluorescence probe comprised of anti-MT1-MMP monoclonal antibodies conjugated to self-assembling polymer micelles that encapsulate NIR dyes (IC7-1, λ_em: 858 nm) at concentrations sufficient to cause fluorescence self-quenching. In aqueous buffer, MT1-hIC7L fluorescence was suppressed to background levels and increased approximately 35.5-fold in the presence of detergent. Cellular uptake experiments revealed that in MT1-MMP positive C6 glioma cells, MT1-hIC7L showed significantly higher fluorescence that increased with time as compared to hIC7L, a negative control probe lacking the anti-MT1-MMP monoclonal antibody. In MT1-MMP negative MCF-7 breast adenocarcinoma cells, both MT1-hIC7L and hIC7L showed no obvious fluorescence. In addition, the fluorescence intensity of C6 cells treated with MT1-hIC7L was suppressed by pre-treatment with an MT1-MMP endocytosis inhibitor (P < 0.05). In vivo optical imaging using probes intravenously administered to tumor-bearing mice showed that MT1-hIC7L specifically visualized C6 tumors (tumor-to-background ratios: 3.8 ± 0.3 [MT1-hIC7L] vs 3.1 ± 0.2 [hIC7L] 48 h after administration, P < 0.05), while the probes showed similarly low fluorescence in MCF-7 tumors. Together, these results show that MT1-hIC7L would be a potential activatable NIR probe for specifically detecting MT1-MMP-expressing tumors.

Au nanomatryoshkas as efficient near-infrared photothermal transducers for cancer treatment: benchmarking against nanoshells

Au nanoparticles with plasmon resonances in the near-infrared (NIR) region of the spectrum efficiently convert light into heat, a property useful for the photothermal ablation of cancerous tumors subsequent to nanoparticle uptake at the tumor site. A critical aspect of this process is nanoparticle size, which influences both tumor uptake and photothermal efficiency. Here, we report a direct comparative study of ∼90 nm diameter Au nanomatryoshkas (Au/SiO2/Au) and ∼150 nm diameter Au nanoshells for photothermal therapeutic efficacy in highly aggressive triple negative breast cancer (TNBC) tumors in mice. Au nanomatryoshkas are strong light absorbers with 77% absorption efficiency, while the nanoshells are weaker absorbers with only 15% absorption efficiency. After an intravenous injection of Au nanomatryoshkas followed by a single NIR laser dose of 2 W/cm(2) for 5 min, 83% of the TNBC tumor-bearing mice appeared healthy and tumor free >60 days later, while only 33% of mice treated with nanoshells survived the same period. The smaller size and larger absorption cross section of Au nanomatryoshkas combine to make this nanoparticle more effective than Au nanoshells for photothermal cancer therapy.

New generation of magnetic and luminescent nanoparticles for in vivo real-time imaging

A new generation of optimized contrast agents is emerging, based on metallic nanoparticles (NPs) and semiconductor nanocrystals for, respectively, magnetic resonance imaging (MRI) and near-infrared (NIR) fluorescent imaging techniques. Compared with established contrast agents, such as iron oxide NPs or organic dyes, these NPs benefit from several advantages: their magnetic and optical properties can be tuned through size, shape and composition engineering, their efficiency can exceed by several orders of magnitude that of contrast agents clinically used, their surface can be modified to incorporate specific targeting agents and antifolding polymers to increase blood circulation time and tumour recognition, and they can possibly be integrated in complex architecture to yield multi-modal imaging agents. In this review, we will report the materials of choice based on the understanding of the basic physics of NIR and MRI techniques and their corresponding syntheses as NPs. Surface engineering, water transfer and specific targeting will be highlighted prior to their first use for in vivo real-time imaging. Highly efficient NPs that are safer and target specific are likely to enter clinical application in a near future.

Spectroscopic limb monitoring in peripheral extracorporeal membrane oxygenation

Limb-related complications are major contributors to extracorporeal membrane oxygenation-associated complications. Early detection of limb ischemia and or compartment syndrome is paramount to minimizing the adverse effects. With the absence of pulsatile flow, bedside Doppler examination of distal arterial waveforms is an impractical and an unreliable method of monitoring limb perfusion. We describe a new application of near-infrared spectroscopy monitoring of tissue oxygenation for the early detection of limb complications in extracorporeal membrane oxygenation.

Excitonic Photoluminescence from Nanodisc States in Graphene Oxides

The origin of near-infrared (NIR) luminescence from graphene oxide (GO) is investigated by photoluminescence (PL) excitation spectroscopy, time-resolved PL spectroscopy, and density functional theory based many body perturbation theories. The energy of experimentally observed NIR PL peak depends on the excitation energy, and the peak broadens with increasing excitation energy. It is found that the PL decay curves in time-resolved spectroscopy show build-up behavior at lower emission energies due to energy transfer between smaller to larger graphene nanodisc (GND) states embedded in GO. We demonstrate that the NIR PL originates from ensemble emission of GND states with a few nanometers in size. The theoretical calculations reveal the electronic and excitonic properties of individual GND states with various sizes, which accounts for the inhomogeneously broadened NIR PL. We further demonstrate that the electronic properties are highly sensitive to the protonation and deprotonation processes of GND states using both the experimental and theoretical approaches.

The surprising in vivo instability of near-IR-absorbing hollow Au-Ag nanoshells

Photothermal ablation based on resonant illumination of near-infrared-absorbing noble metal nanoparticles that have accumulated in tumors is a highly promising cancer therapy, currently in multiple clinical trials. A crucial aspect of this therapy is the nanoparticle size for optimal tumor uptake. A class of nanoparticles known as hollow Au (or Au-Ag) nanoshells (HGNS) is appealing because near-IR resonances are achievable in this system with diameters less than 100 nm. However, in this study, we report a surprising finding that in vivo HGNS are unstable, fragmenting with the Au and the remnants of the sacrificial Ag core accumulating differently in various organs. We synthesized 43, 62, and 82 nm diameter HGNS through a galvanic replacement reaction, with nanoparticles of all sizes showing virtually identical NIR resonances at ∼800 nm. A theoretical model indicated that alloying, residual Ag in the nanoparticle core, nanoparticle porosity, and surface defects all contribute to the presence of the plasmon resonance at the observed wavelength, with the major contributing factor being the residual Ag. While PEG functionalization resulted in stable nanoparticles under laser irradiation in solution, an anomalous, strongly element-specific biodistribution observed in tumor-bearing mice suggests that an avid fragmentation of all three sizes of nanoparticles occurred in vivo. Stability studies across a wide range of pH environments and in serum confirmed HGNS fragmentation. These results show that NIR resonant HGNS contain residual Ag, which does not stay contained within the HGNS in vivo. This demonstrates the importance of tracking both materials of a galvanic replacement nanoparticle in biodistribution studies and of performing thorough nanoparticle stability studies prior to any intended in vivo trial application.

Light-Induced Remodeling of Physically Crosslinked Hydrogels Using Near-IR Wavelengths

Poly([6-bromo-7-hydroxycoumarin-4-yl]methyl methacrylate)-based triblock copolymers were synthesized by first preparing PMAA-PEG-PMAA triblocks using ATRP. 6-Bromo-4-chloromethyl-7-hydroxycoumarin was conjugated to PMAA-PEG-PMAA using 1,8-diazabicycloundec-7-ene (DBU). Rheological measurements were conducted using a HR-2 rheometer with a UV illumination accessory (TA Instruments). Single-photon uncaging was performed as previously described.20 Two-photon uncaging was performed using a LSM (Zeiss) equipped with a Ti: Sapphire laser (Coherent). All values reported as mean ± std. dev. unless otherwise stated. See Supporting Information for experimental details.

CH3NH3SnxPb(1-x)I3 Perovskite Solar Cells Covering up to 1060 nm

We report photovoltaic performances of all-solid state Sn/Pb halide-based perovskite solar cells. The cell has the following composition: F-doped SnO2 layered glass/compact titania layer/porous titania layer/CH3NH3SnxPb(1-x)I3/regioregular poly(3-hexylthiophene-2,5-diyl). Sn halide perovskite itself did not show photovoltaic properties. Photovoltaic properties were observed when PbI2 was added in SnI2. The best performance was obtained by using CH3NH3Sn0.5Pb0.5I3 perovskite. 4.18% efficiency with open circuit voltage 0.42 V, fill factor 0.50, and short circuit current 20.04 mA/cm(2) are reported. The edge of the incident photon to current efficiency curve reached 1060 nm, which was 260 nm red-shifted compared with that of CH3NH3PbI3 perovskite solar cells.

A rapid, direct, quantitative, and label-free detector of cardiac biomarker troponin T using near-infrared fluorescent single-walled carbon nanotube sensors

Patients with chest pain account for 10% of US emergency room visits according to data from the Center for Disease Control and Prevention (2013). For triage of these patients, cardiac biomarkers troponin I and T are endorsed as standard indicators for acute myocardial infarction (AMI, or heart attack). Thus, there is significant interest in developing a rapid, point-of-care (POC) device for troponin detection. In this work, a rapid, quantitative, and label-free assay, which is specific for cardiac troponin T (cTnT) detection, using fluorescent single-walled carbon nanotubes (SWCNTs), is demonstrated. Chitosan-wrapped carbon nanotubes are cross-linked to form a thin gel that is further functionalized with nitrilotriacetic acid (NTA) moieties. Upon chelation of Ni(2+) , the Ni(2+) -NTA group binds to a hexa-histidine-modified troponin antibody, which specifically recognizes the target protein, troponin T. As the troponin T binds to the antibody, the local environment of the sensor changes, allowing direct troponin detection through intensity changes in SWCNT bandgap fluorescence. This platform represents the first near-infrared SWCNT sensor array for cTnT detection. Detection can be completed within 5 min, demonstrating a linear response to cTnT concentration and an experimental detection limit of 100 ng mL(-1) (2.5 nm). This platform provides a promising new tool for POC AMI detection in the future. Moreover, the work presents two new methods of quantifying the number of amines and carboxylic groups, respectively, in a carbon hydrogel matrices.

Comparison of multiple enzyme activatable near-infrared fluorescent molecular probes for detection and quantification of inflammation in murine colitis models

BACKGROUND

Activatable near-infrared fluorescent (NIRF) probes have been used for ex vivo and in vivo detection of intestinal tumors in animal models. We hypothesized that NIRF probes activatable by cathepsins or metalloproteinases will detect and quantify dextran sulphate sodium (DSS)-induced acute colonic inflammation in wild type mice or chronic colitis in interleukin-10 (IL-10)-null mice ex vivo or in vivo.

METHODS

Wild type mice given DSS, water controls, and IL-10-null mice with chronic colitis were administered probes by retro-orbital injection. FMT2500 LX system imaged fresh and fixed intestine ex vivo and mice in vivo. Inflammation detected by probes was verified by histology and colitis scoring. NIRF signal intensity was quantified using 2-dimensional region of interest ex vivo or 3-dimensional region of interest analysis in vivo.

RESULTS

Ex vivo, 7 probes tested yielded significant higher NIRF signals in colon of DSS-treated mice versus controls. A subset of probes was tested in IL-10-null mice and yielded strong ex vivo signals. Ex vivo fluorescence signal with 680 series probes was preserved after formalin fixation. In DSS and IL-10-null models, ex vivo NIRF signal strongly and significantly correlated with colitis scores. In vivo, ProSense680, CatK680FAST, and MMPsense680 yielded significantly higher NIRF signals in DSS-treated mice than controls, but background was high in controls.

CONCLUSIONS

Both cathepsin or metalloproteinase-activated NIRF probes can detect and quantify colonic inflammation ex vivo. ProSense680 yielded the strongest signals in DSS colitis ex vivo and in vivo, but background remains a problem for in vivo quantification of colitis.

Prediction of retinal pigment epithelial tear in serous vascularized pigment epithelium detachment

PURPOSE

The aim of the study was to identify predictive factors for detection of impending retinal pigment epithelium (RPE) tears in patients under anti-VEGF therapy for treatment of retinal pigment epithelial detachment (PED) due to exudative age-related macular degeneration (AMD) using near-infrared reflectance imaging (NIR), spectral-domain optical coherence tomography (SD-OCT) and fluorescein angiography (FLA).

METHODS

We retrospectively evaluated NIR, SD-OCT and FLA images, number of intravitreal injections as well as demographical data of 103 eyes of 98 patients with vascularized PED [48.5% fibrovascular PED (fPED), 51.5% serous vascularized PED (svPED)] secondary to AMD.

RESULTS

Fifteen eyes with svPED of 103 included eyes (14.6%) developed an RPE tear under anti-VEGF therapy. Prior to RPE tear formation, we could identify radial hyperreflective lines spreading in a funnel-like pattern across the PED lesion in NIR images in 11 eyes correlating with folds in the RPE on corresponding SD-OCT scans (mean observation period: 115.4 ± 66.6 days; mean number of injections: 3.2 ± 1.5; mean PED height 828.2 ± 356.5 μm). In nine RPE tears (81.8%), the edge of the tear could be clearly localized on the opposite side of the PED lesion in relation to the origin of hyperreflective lines. None of the fPED patients showed the described signal.

CONCLUSIONS

Patients under anti-VEGF therapy for treatment of svPED due to AMD frequently show radial hyperreflective lines in NIR images prior to RPE tear development that correspond to wrinkled changes in the RPE. Hyperreflective lines may serve as an indicator for an impending RPE tear in svPED patients.

meso-Ester and carboxylic acid substituted BODIPYs with far-red and near-infrared emission for bioimaging applications

A series of meso-ester-substituted BODIPY derivatives 1-6 are synthesized and characterized. In particular, dyes functionalized with oligo(ethylene glycol) ether styryl or naphthalene vinylene groups at the α positions of the BODIPY core (3-6) become partially soluble in water, and their absorptions and emissions are located in the far-red or near-infrared region. Three synthetic approaches are attempted to access the meso-carboxylic acid (COOH)-substituted BODIPYs 7 and 8 from the meso-ester-substituted BODIPYs. Two feasible synthetic routes are developed successfully, including one short route with only three steps. The meso-COOH-substituted BODIPY 7 is completely soluble in pure water, and its fluorescence maximum reaches around 650 nm with a fluorescence quantum yield of up to 15 %. Time-dependent density functional theory calculations are conducted to understand the structure-optical properties relationship, and it is revealed that the Stokes shift is dependent mainly on the geometric change from the ground state to the first excited singlet state. Furthermore, cell staining tests demonstrate that the meso-ester-substituted BODIPYs (1 and 3-6) and one of the meso-COOH-substituted BODIPYs (8) are very membrane-permeable. These features make these meso-ester- and meso-COOH-substituted BODIPY dyes attractive for bioimaging and biolabeling applications in living cells.

Near-infrared spectroscopy: exposing the dark (venous) side of the circulation

The safety of anesthesia has improved greatly in the past three decades. Standard perioperative monitoring, including pulse oximetry, has practically eliminated unrecognized arterial hypoxia as a cause for perioperative injury. However, most anesthesia-related cardiac arrests in children are now cardiovascular in origin, and standard monitoring is unable to detect many circulatory abnormalities. Near-infrared spectroscopy provides noninvasive continuous access to the venous side of regional circulations that can approximate organ-specific and global measures to facilitate the detection of circulatory abnormalities and drive goal-directed interventions to reduce end-organ ischemic injury.

Raman and coherent anti-Stokes Raman scattering microscopy studies of changes in lipid content and composition in hormone-treated breast and prostate cancer cells

Increasing interest in the role of lipids in cancer cell proliferation and resistance to drug therapies has motivated the need to develop better tools for cellular lipid analysis. Quantification of lipids in cells is typically done by destructive chromatography protocols that do not provide spatial information on lipid distribution and prevent dynamic live cell studies. Methods that allow the analysis of lipid content in live cells are therefore of great importance. Using micro-Raman spectroscopy and coherent anti-Stokes Raman scattering (CARS) microscopy, we generated a lipid profile for breast (T47D, MDA-MB-231) and prostate (LNCaP, PC3) cancer cells upon exposure to medroxyprogesterone acetate (MPA) and synthetic androgen R1881. Combining Raman spectra with CARS imaging, we can study the process of hormone-mediated lipogenesis. Our results show that hormone-treated cancer cells T47D and LNCaP have an increased number and size of intracellular lipid droplets and higher degree of saturation than untreated cells. MDA-MB-231 and PC3 cancer cells showed no significant changes upon treatment. Principal component analysis with linear discriminant analysis of the Raman spectra was able to differentiate between cancer cells that were treated with MPA, R1881, and untreated.

A comparative study of affibody, panitumumab, and EGF for near-infrared fluorescence imaging of EGFR- and EGFRvIII-expressing tumors

Aberrant overexpression and/or activation of epidermal growth factor receptor (EGFR) is associated with many types of cancers. EGFR variant III (EGFRvIII) is a common in-frame deletion mutant, which lacks a large part of the extracellular portion (exons 2-7), including components of the ligand-binding domain. Although EGFR has been extensively studied as a molecular imaging target, information about EGFRvIII-targeted molecular imaging is lacking. In this study, the EGFR-specific affibody, therapeutic antibody panitumumab, and ligand EGF were labeled with IRDye 800CW (Ex/Em: 774/789 nm), yielding Aff800, Pan800, and EGF800, respectively. The binding affinities of the labeled agents were compared in cell-based assays using a rat glioma cell line F98 parental (F98-p) lacking EGFR expression, and 2 F98-derived transgenic cell lines expressing EGFR or EGFRvIII (designated as F98-EGFR and F98-vIII, respectively). Results showed that all agents could bind to F98-EGFR, with Pan800 having the highest binding affinity, followed by Aff800 and EGF800. Pan800 and Aff800, but not EGF800, also bound to F98-vIII. In vivo animal imaging demonstrated that compared with F98-p tumors, F98-EGFR tumors generated higher signals with all three agents. However, in the case of F98-vIII, only Pan800 and Aff800 signals were higher. Analysis of tissue lysates showed that a large portion of Pan800 was degraded into small fragments in F98-EGFR and F98-vIII tumors, possibly due to proteolytic digestion after its specific binding and internalization. In conclusion, Pan800 and Aff800 could be used as imaging agents for both wild-type EGFR and EGFRvIII, whereas EGF800 only targets wild-type EGFR.

Tunable Band Gap Emission and Surface Passivation of Germanium Nanocrystals Synthesized in the Gas Phase

The narrow bulk band gap and large exciton Bohr radius of germanium (Ge) make it an attractive material for optoelectronics utilizing band-gap-tunable photoluminescence (PL). However, realization of PL due to quantum confinement remains scarcely reported. Instead, PL is often observed from surface trap states and is independent of nanocrystal (NC) size. Here, we demonstrate tunable band gap PL by chemically passivating the Ge NC surface. The exchange of native Ge-Cl surface groups with alkyl groups using Grignard reagents leads to the first instance of tunable band gap emission from free-standing Ge NCs synthesized in the gas phase. Ge NCs between 4.8 and 10.2 nm in diameter exhibit near-infrared emission featuring spectral line widths that are at least a factor of 2 narrower than any previous report.

Two-color fluorescent (near-infrared and visible) triphasic perfluorocarbon nanoemuslions

Design and development of a new formulation as a unique assembly of distinct fluorescent reporters with nonoverlapping fluorescence spectra and a F19 magnetic resonance imaging agent into colloidally and optically stable triphasic nanoemulsion are reported. Specifically, a cyanine dye-perfluorocarbon (PFC) conjugate was introduced into the PFC phase of the nanoemulsion and a near-infrared dye was introduced into the hydrocarbon (HC) layer. To the best of our knowledge, this is the first report of a triphasic nanoemulsion system where each oil phase, HC, and PFC are fluorescently labeled and formulated into an optically and colloidally stable nanosystem. Having, each oil phase separately labeled by a fluorescent dye allows for improved correlation between in vivo imaging and histological data. Further, dual fluorescent labeling can improve intracellular tracking of the nanodroplets and help assess the fate of the nanoemulsion in biologically relevant media. The nanoemulsions were produced by high shear processing (microfluidization) and stabilized with biocompatible nonionic surfactants resulting in mono-modal size distribution with average droplet size less than 200 nm. Nanoemulsions demonstrate excellent colloidal stability and only moderate changes in the fluorescence signal for both dyes. Confocal fluorescence microscopy of macrophages exposed to nanoemulsions shows the presence of both fluorescence agents in the cytoplasm.

Non-invasive metabolomic analysis using a commercial NIR instrument for embryo selection

CONTEXT:

Metabolomics was introduced in human in vitro fertilization (IVF) for noninvasive identification of viable embryos with the highest developmental competence.

AIMS:

To determine whether embryo selection using a commercial version of metabolomic analysis leads to increased implantation rates (IRs) with fetal cardiac activity (FCA) compared with morphology evaluation alone.

SETTING AND DESIGN:

Randomized controlled trial from April to December 2010 at a private IVF unit. The study was terminated prematurely due to the market withdrawal of the instrument.

MATERIALS AND METHODS:

IVF patients ≥18 and ≤43 years with ≥4 × 2PN were randomly allocated to metabolomic analysis combined with embryo morphology (ViaMetrics-E; metabolomics + morphology group) or embryo morphology alone (morphology group). Cycles with frozen embryos, oocyte donations, or testicular biopsy were excluded.

STATISTICAL ANALYSIS:

Categorical and continuous data were analyzed for statistical significance using 2-tailed Fisher's exact test and t-test, respectively. Statistical significance was accepted when P > 0.05.

RESULTS:

A total of 125 patients were included in the study; 39 patients were allocated to metabolomics + morphology group and 86 patients to morphology group. Patients were stratified according to the day of embryo transfer (Days 2, 3, or 5). IRs with FCA were similar for Days 2 and 3 transfers in both groups. For Day 5 transfers, IRs with FCA were significantly higher in the metabolomics + morphology group (46.8% vs. 28.9%; P = 0.041; 95% confidence intervalp [CI]: 1.09-34.18). Pregnancy and live births rates were similar for Days 2, 3, and 5 in both groups. The study was terminated early following the voluntary market withdrawal of ViaMetrics-E in December 2010.

CONCLUSIONS:

Metabolomic analysis using the commercial near-infrared (NIR) instrument does not appear to have a beneficial effect on pregnancy and live births, with improvement in IR with FCA for Day 5 transfers. However, no solid conclusions can be reached due to the lack of adequate study power.ClinicalTrials.gov Identifier: NCT01490515

Novel strategy combining SYBR Green I with carbon nanotubes for highly sensitive detection of Salmonella typhimurium DNA

A simple, selective, sensitive and label-free fluorescent method for detecting trpS-harboring Salmonella typhimurium was developed in this study. This assay used the non-covalent interaction of single-stranded DNA (ssDNA) probes with SWNTs, since SWNTs can quench fluorescence. Fluorescence recovery (78% with 1.8 nM target DNA) was detected in the presence of target DNA as ssDNA probes detached from SWNTs hybridized with target DNA, and the resulting double-stranded DNA (dsDNA) intercalated with SYBR Green I (SG) dyes. The increasing fluorescence intensity reached 4.54-fold. In contrast, mismatched oligonucleotides (1- or 3-nt difference to the target DNA) did not contribute to significant fluorescent recovery, which demonstrated the specificity of the assay. The increasing fluorescence intensity increased 3.15-fold when purified PCR products containing complementary sequences of trpS gene were detected. These results confirmed the ability to use this assay for detecting real samples.

Plasmonic photothermal heating of intraperitoneal tumors through the use of an implanted near-infrared source

Plasmonic nanomaterials including gold nanorods are effective agents for inducing heating in tumors. Because near-infrared (NIR) light has traditionally been delivered using extracorporeal sources, most applications of plasmonic photothermal therapy have focused on isolated subcutaneous tumors. For more complex models of disease such as advanced ovarian cancer, one of the primary barriers to gold nanorod-based strategies is the adequate delivery of NIR light to tumors located at varying depths within the body. To address this limitation, a series of implanted NIR illumination sources are described for the specific heating of gold nanorod-containing tissues. Through computational modeling and ex vivo studies, a candidate device is identified and validated in a model of orthotopic ovarian cancer. As the therapeutic, imaging, and diagnostic applications of plasmonic nanomaterials progress, effective methods for NIR light delivery to challenging anatomical regions will complement ongoing efforts to advance plasmonic photothermal therapy toward clinical use.

Microscope-based near-infrared stereo-imaging system for quantifying the motion of the murine epicardial coronary arteries in vivo

Atherosclerosis is a leading cause of mortality in industrialized countries. In addition to "traditional" systemic risk factors for atherosclerosis, the geometry and motion of coronary arteries may contribute to individual susceptibility to the development and progression of disease in these vessels. To be able to test this, we have developed a high-speed (∼40 frames per second) microscope-based stereo-imaging system to quantify the motion of epicardial coronary arteries of mice. Using near-infrared nontargeted quantum dots as an imaging contrast agent, we synchronously acquired paired images of a surgically exposed murine heart, from which the three-dimensional geometry of the coronary arteries was reconstructed. The reconstructed geometry was tracked frame by frame through the cardiac cycle to quantify the in vivo motion of the vessel, from which displacements, curvature, and torsion parameters were derived. Illustrative results for a C57BL/6J mouse are presented.