Entries by Katy

Anomalous upconversion amplification induced by surface reconstruction in lanthanide sublattices

Upconversion nanocrystals have been extensively investigated for optical imaging and biomedical applications1,2. However, their photoluminescence is strongly attenuated by surface quenching as the nanocrystal size diminishes3. Despite considerable efforts4,5, the quenching mechanism remains poorly understood. Here we report that surface coordination of bidentate picolinic acid molecules to NaGdF4:Yb/Tm nanoparticles enhances four-photon upconversion by 11,000-fold. Mechanistic […]

Glycerol-in-SEBS gel as a material to manufacture stable wall-less vascular phantom for ultrasound and photoacoustic imaging

Styrene-ethylene/butylene-styrene (SEBS) copolymer-in-mineral oil gel is an appropriate tissue-mimicking material to manufacture stable phantoms for ultrasound and photoacoustic imaging. Glycerol dispersion has been proposed to further tune the acoustic properties and to incorporate hydrophilic additives into SEBS gel. However, this type of material has not been investigated to produce wall-less vascular flow phantom for these […]

Gold nanoparticles conjugated with DNA aptamer for photoacoustic detection of human matrix metalloproteinase-9

Matrix metalloproteinase-9 (MMP-9) plays major roles in extracellular matrix (ECM) remodeling and membrane protein cleavage, suggesting a high correlation with cancer cell invasion and tumor metastasis. Here, we present a contrast agent based on a DNA aptamer that can selectively target human MMP-9 in the tumor microenvironment (TME) with high affinity and sensitivity. Surface modification of plasmonic gold nanospheres with the MMP-9 aptamer and its complementary sequences allows the […]

Direct Water-Assisted Laser Desorption/Ionization Mass Spectrometry Lipidomic Analysis and Classification of Formalin-Fixed Paraffin-Embedded Sarcoma Tissues without Dewaxing 

Formalin-fixed paraffin-embedded (FFPE) tissue has been the gold standard for routine pathology for general and cancer postoperative diagnostics. Despite robust histopathology, immunohistochemistry, and molecular methods, accurate diagnosis remains difficult for certain cases. Overall, the entire process can be time consuming, labor intensive, and does not reach over 90% diagnostic sensitivity and specificity. There is a […]

Deep-ultraviolet laser ablation sampling for proteomic analysis of tissue

Deep-ultraviolet laser ablation with a pulsed 193 nm ArF excimer laser was used to remove localized regions from tissue sections from which proteins were extracted for spatially resolved proteomic analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS). The ability to capture intact proteins by ablation at 193 nm wavelength was verified by matrix-assisted laser desorption ionization (MALDI) of the protein standard bovine serum albumin (BSA), which showed […]

Direct measurement of neuronal ensemble activity using photoacoustic imaging in the stimulated Fos-LacZ transgenic rat brain: A proof-of-principle study

Measuring neuroactivity underlying complex behaviors facilitates understanding the microcircuitry that supports these behaviors. We have developed a functional and molecular photoacoustic tomography (F/M-PAT) system which allows direct imaging of Fos-expressing neuronal ensembles in Fos-LacZ transgenic rats with a large field-of-view and high spatial resolution. F/M-PAT measures the beta-galactosidase catalyzed enzymatic product of exogenous chromophore X-gal […]

Design of scanning robot for atherosclerosis detection via photoacoustic imaging

In recent years, cardiovascular disease, as the most fatal disease, has attracted widespread attention. We designed a scanning robot to detect carotid artery based on photoacoustic theory. We simply clamp the photoacoustic probe already in the laboratory on this robot. It can replace the doctor’s manual inspection. Play the role of liberating hands. In this […]

Excitation, emission, and synchronous fluorescence for astrochemical applications: Experiments and computer simulations of synchronous spectra of polycyclic aromatic hydrocarbons and their mixtures

Synchronous fluorescence spectroscopy is a variation of the fluorescence technique for detection and characterization of many single ring aromatic organic molecules, polycyclic aromatic hydrocarbons, and fluorescent amino acids among other molecules. To our knowledge this technique has not been used in space exploration. In order to demonstrate the utility of this technique for planetary and astrochemical applications, we […]

Photoinduced energy transfer in truxene-linked zinc porphyrin–fullerene-corrole tetrad and its application in triplet−triplet annihilation upconversion

Triplet photosensitizers (PSs) have attracted widespread interest due to their application in photocatalytic organic reactions, photodynamic therapy (PDT), photoinduced hydrogen production from water splitting, and triplet–triplet annihilation (TTA) upconversion. Herein, the triad T-P-Co and tetrad T-C60-P-Co were synthesized, characterized, and applied in triplet–triplet annihilation (TTA) upconversion. The photophysical processes were investigated with steady-state UV–visible absorption and fluorescence spectroscopies, nanosecond time-resolved transient absorption spectroscopy and electrochemical […]

Detection of collagen by multi-wavelength photoacoustic analysis as a biomarker for bone health assessment

Collagen is an important biomarker of osteoporosis progression. Noninvasive, multispectral, photoacoustic (PA) techniques use pulsed laser light to induce PA signals to facilitate the visualization of chemical components that are strongly related to tissue health. In this study, the feasibility of multi-wavelength PA (MWPA) measurement of the collagen in bone, using the wavelength range of 1300–1800 nm, was investigated. First, the feasibility […]