In vivo fluorescence spectroscopy of nonmelanoma skin cancer

In vivo and ex vivo tissue autofluorescence (endogenous fluorescence) have been employed to investigate the presence of markers that could be used to detect tissue abnormalities and/or malignancies. We present a study of the autofluorescence of normal skin and tumor in vivo, conducted on 18 patients diagnosed with nonmelanoma skin cancers (NMSC). We observed that both in basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) the endogenous fluorescence due to tryptophan residues was more intense in tumor than in normal tissue, probably due to epidermal thickening and/or hyperproliferation. Conversely, the fluorescence intensity associated with dermal collagen crosslinks was generally lower in tumors than in the surrounding normal tissue, probably because of degradation or erosion of the connective tissue due to enzymes released by the tumor. The decrease of collagen fluorescence in the connective tissue adjacent to the tumor loci was validated by fluorescence imaging on fresh-frozen tissue sections obtained from 33 NMSC excised specimens. Our results suggest that endogenous fluorescence of NMSC, excited in the UV region of the spectrum, has characteristic features that are different from normal tissue and may be exploited for noninvasive diagnostics and for the detection of tumor margins.     

On-line detection of human skin vapors

Vapors released by the skin in the hand of one human subject are detected in real time by sampling them directly from the ambient gas surrounding the hand, ionizing them by secondary electrospray ionization (SESI, via contact with the charged cloud from an electrospray source), and analyzing them in a mass spectrometer with an atmospheric pressure source (API-MS). This gas-phase approach is complementary to alternative on-line surface ionization methods such as DESI and DART. A dominating peak of lactic acid and a complete series of saturated and singly unsaturated fatty acids (C₁₂ to C₁₈) are observed, in accordance with previous off-line studies by gas chromatography-mass spectrometry. Several other metabolites have been identified, including ketomonocarboxylic and hydroxymonocarboxylic acids.     

MALDI-MS imaging of lipids in ex vivo human skin

Lipidomics is a rapidly expanding area of scientific research and there are a number of analytical techniques that are employed to facilitate investigations. One such technique is matrix-assisted laser desorption ionisation (MALDI) mass spectrometry (MS). Previous MALDI-MS studies involving lipidomic investigation have included the analysis of a number of different ex vivo tissues, most of which were obtained from animal models, with only a few being of human origin. In this study, we describe the use of MALDI-MS, MS/MS and MS imaging methods for analysing lipids within cross-sections of ex vivo human skin. It has been possible to tentatively identify lipid species via accurate mass measurement MALDI-MS and also to confirm the identity of a number of these species via MALDI-MS/MS, in experiments carried out directly on tissue. The main lipid species detected include glycerophospholipids and sphingolipids. MALDI images have been generated at a spatial resolution of 150 and 30 μm, using a MALDI quadrupole time-of-flight Q-Star Pulsar-i ^TM (Applied Biosystems/MDS Sciex, Concord, ON, Canada) and a MALDI high-definition MS (HDMS) SYNAPT G2-HDMS^TM system (Waters, Manchester, UK), respectively. These images show the normal distribution of lipids within human skin, which will provide the basis for assessing alterations in lipid profiles linked to specific skin conditions e.g. sensitisation, in future investigations.     

On the assessment of melanin in human skin in vivo

Abstract— A method for estimating the amount of pigment in normal human skin in uivo is presented. This method is based on remittance spectroscopy. The spectrum of normal skin is compared to amelanotic skin and the logarithm of the ratio is fitted with a straight line in the range 620-720 nm. The parameters obtained are strongly correlated for all the volunteers in this study. therefore each spectrum determines one parameter for each individual. When similar analysis was performed on DOPA-melanin we obtained the same strong correlation among different concentrations. We are thus able to determine a relation between the coefficient obtained from the remittance spectrum from normal skin and an equivalent concentration of DOPA-melanin in aqueous solution. We can thus estimate. to a first approximation, the total melanin mass in human skin non-invasively, and can determine a parameter that is uniquely correlated to the amount of melanin pigment in the skin.     

A novel off-on fluorescent probe for specific detection and imaging of cysteine in live cells and in vivo

Cysteine(Cys) plays a pivotal role in many physiological and pathological processes,including detoxification and protein synthesis.The abnormal levels of Cys are linked to many diseases.In this study,a novel red-emitting off-on fluorescent probe Cys-TCF was masterly constructed for discriminative detection of Cys.After a series of experimental assessment,Cys-TCF displayed higher selectivity and sensitivity for Cys over other biothilols with a low detection limit(0.04 μmol/L).More notably,the pro...     

Chitosan coated carbon fiber microelectrode for selective in vivo detection of neurotransmitters in live zebrafish embryos

We report the development of a chitosan modified carbon fiber microelectrode for in vivo detection of serotonin. We find that chitosan has the ability to reject physiological levels of ascorbic acid interferences and facilitate selective and sensitive detection of in vivo levels of serotonin, a common catecholamine neurotransmitter. Presence of chitosan on the microelectrode surface was investigated using scanning electron microscopy (SEM) and cyclic voltammetry (CV). The electrode was characterized using differential pulse voltammetry (DPV). A detection limit of 1.6 nM serotonin with a sensitivity of 5.12 nA/μM, a linear range from 2 to 100 nM and a reproducibility of 6.5% for n=6 electrodes were obtained. Chitosan modified microelectrodes selectively measure serotonin in presence of physiological levels of ascorbic acid. In vivo measurements were performed to measure concentration of serotonin in the live embryonic zebrafish intestine. The sensor quantifies in vivo intestinal levels of serotonin while successfully rejecting ascorbic acid interferences. We demonstrate that chitosan can be used as an effective coating to reject ascorbic acid interferences at carbon fiber microelectrodes, as an alternative to Nafion, and that chitosan modified microelectrodes are reliable tools for in vivo monitoring of changes in neurotransmitter levels.     

In vivo mTHPC photobleaching in normal rat skin exhibits unique irradiance-dependent features

We report measurements performed on the normal skin of rats in vivo, which provide information on the photobleaching kinetics and mechanisms of the photosensitizer meso-tetrahydroxyphenyl chlorin (mTHPC). Loss of mTHPC fluorescence was monitored using in vivo fluorescence spectroscopy during photodynamic therapy (PDT) performed using 650 nm laser irradiation. The bleaching was evaluated for irradiances of 5, 20 and 50 mW cm(-2). Two distinct phases of mTHPC photobleaching were observed. In the first phase there was no obvious irradiance dependence in the loss of fluorescence vs fluence. The second phase was initiated by an irradiance-dependent discontinuity in the slope of the bleaching curve, after which the photobleaching rates showed an irradiance dependence consistent with an oxygen-dependent reaction process. To investigate the unusual shape of the in vivo bleaching curves, we measured the PDT-induced changes in O2 concentrations in mTHPC-sensitized spheroids irradiated with 2, 5 and 20 mW cm(-2) of 650 nm light. The oxygen concentration data indicated no unusual features within the range of fluences where the discontinuities in fluorescence were observed during in vivo spectroscopy. The fluorescence from the in vivo bleaching experiments thus reports a phenomenon that is not reported by measurements of the photochemical oxygen consumption in the spheroids.     

Observation and quantification of ultraviolet-induced reactive oxygen species in ex vivo human skin

Two-photon fluorescence imaging is used to detect UV-induced reactive oxygen species (ROS) in ex vivo human skin in this study. ROS (potentially H202, singlet oxygen or peroxynitrite [or all]) are detected after reaction with nonfluorescent dihydrorhodamine-123 (DHR) and the consequent formation of fluorescent rhodamine-123 (R123). The cellular regions at each epidermal stratum that generate ROS are identified. R-123 fluorescence is detected predominately in the lipid matrix of the stratum corneum. In contrast, the strongest R123 fluorescence signal is detected in the intracellular cytoplasm of the viable epidermal keratinocytes. A simple bimolecular one-step kinetic model is used for estimating the upper bound of the number of ROS that are generated in the skin and that react with DHR. After ultraviolet-B radiation (280-320 nm) (UVB) equivalent to 2 h of noonday summer North American solar exposure (1600 J m(-2) UVB), the model finds that 14.70 x 10(-3) mol of ROS that react with DHR are generated in the stratum corneum of an average adult-size face (258 cm(-2)). Approximately 10(-4) mol are potentially generated in the lower epidermal strata. The data show that two-photon fluorescence imaging can be used to detect ROS in UV-irradiated skin.     

In vitro and in vivo inhibition of skin matrix metalloproteinases by Pothomorphe umbellata root extract

Exposure to UV radiation up-regulates the synthesis of matrix metalloproteinases (MMPs), a group of matrix-degrading enzymes. MMPs are regarded as promising therapeutic targets and the development of effective inhibitors is an important research focus. The plant Pothomorphe umbellata has been shown to exert a potent antioxidant activity on the skin and to delay the onset and reduce the incidence of UVB-induced chronic skin damage. The aim of the present study was to determine the effect of P. umbellata ethanolic root extract on MMP-2 and MMP-9. The in vitro inhibition of MMP-2 and MMP-9 was measured by gelatin zymography in the presence of different concentrations of P. umbellata extract, as well as in the presence of its isolated active principle 4-nerolidylcatechol (4-NC). The inhibitory effect of the P. umbellata extract was stronger than that of 4-NC. Gelatin zymography and histological analysis revealed that P. umbellata was able to inhibit constitutive MMP-9 activity in vivo in mice sacrificed 2 h after UVB irradiation. The intensity of the MMP-2 band was unchanged. Our data contribute to the elucidation of the mechanism of prevention of photoaging by P. umbellata and may provide a rational basis for the use of this plant in prophylaxis against and treatment of skin cancer.     

In situ detection of live cancer cells by using bioprobes based on Au nanoparticles

We fabricate the high-performance probes based on Au nanoparticles (AuNP) for detection of live cancer cell. AuNP were synthesized with narrow sized distribution (ca. 10 nm) by Au salt reduction method and deposited onto the aminated substrate as a cross-linker and hot spot. Herein, AuNP has enabled the easy and efficient immobilization of the antibody (Cetuximab), which can selectively interact with epidermal growth factor receptor (EGFR) on the surface of epidermal cancer, as detecting moiety onto the AuNP-deposited substrate without nanolithography process. After conjugation of Cetuximab with AuNP-deposited substrate, Cetuximab-conjugated probe as a live cancer cell detector (LCCD) could detect EGFR-highexpressed A431 cells related to epithelial cancer with 54-times larger specificity and sensitivity in comparison with EGFR-deficient MCF7 cells. This implies that AuNP-based probes demonstrate abundant potentials for detection and separation of small biomolecules, cells and other chemicals.     

In vivo comparison of the optical clearing efficacy of optical clearing agents in human skin by quantifying permeability using optical coherence tomography

The objective of this work is to quantify and compare the optical clearing efficacy of glucose, propylene glycol, glycerol solutions through the human skin tissue in vivo by calculating permeability coefficient of three solutions. Currently, the permeability coefficient of agent in tissues was extracted from optical coherence tomography (OCT) amplitude data mainly through the OCT signal slope and the OCT amplitude methods. In this study, we report the OCT attenuation coefficient method which is a relatively novel and rarely reported methodology to measure the permeability coefficient during the optical skin clearing procedure. The permeability coefficients for 40% propylene glycol, glucose and glycerol were (2.74 ± 0.05) × 10(-6) cm s(-1), (1.78 ± 0.04) × 10(-6) cm s(-1) and (1.67 ± 0.04) × 10(-6) cm s(-1), respectively. It could be clearly seen that the permeability coefficient of the 40% propylene glycol solution is higher than that of 40% glucose solution, and the permeability coefficient of the 40% glucose solution is higher than that of the 40% glycerol solution. These indicate 40% propylene glycol solution is more effective than others in the human skin in vivo. We then compare and prove consistency of optical clearing efficacy figured out by three different methods.     

Monolayer gas adsorption in plasmonic sensors: Comparative analysis of kinetic models

The analysis of adsorption kinetics is given, assuming no dissociative adsorption takes place and no multiple binding sites exist. The phenomenological nonlinear model and the simple linear model are considered from the point of view of surface plasmon resonance (SPR) chemical sensors. A simple method for analytical calculation of the necessary rate constants is proposed. A comparative analysis of the described models is performed. Two conditions that affect the validity of the linear model are found. First one, referring to the ratio between the overall number of particles and the number of binding sites, and the second one, that guarantees the validity of linear model in much broader spectrum of practical situations, referring to the ratio of rate constants. A method for avoiding the accumulation of numerical errors in calculus is also proposed. The presented approach is general and can be used in various applications, including other types of chemical sensors, membranes for filtering, different catalytic systems, resonant micro or nano-electro-mechanical structures.     

高效液相色谱-化学发光法测定人血清及动物组织中的己烯雌酚

基于己烯雌酚在酸性介质中对Ce(Ⅳ)和Rh6G的化学发光体系的增敏作用,建立了人血清及动物组织中己烯雌酚的高效液相色谱/化学发光检测方法。色谱柱为Welchrom-C18柱(4.6 mm×250 mm,5μm),流动相为甲醇-水(75:25,V/V,pH6.0)。己烯雌酚在1.0×10-8～2.5×10-6g/mL范围内呈良好线性,在优化的实验条件下最低检出限为3.0×10-9g/mL。对5.0×10-7g/mL的己烯雌酚进行11次平行测定,其相对标准偏差为2.1%。     

Recent progress in detection of chemical and biological toxins in Water using plasmonic nanosensors

The supply of safe drinking water is one of the prominent challenges of the world. Water is polluted mainly by chemical and biological toxins which can causes a serious threat to ecosystems and human health. Regular monitoring of chemical and biological toxins in water sources is the primary step in any preventive method. Traditional detection methods include adsorption and chromatography coupled with mass spectrometry. The devices based on these techniques are not easy to be carried for on-site detection and require laborious sample preparation protocols. However, advancements in nanomaterial-based sensors have provided solutions to these challenges. Recent developments in plasmonic sensors lead to extraordinary advancements in the area of ultra-sensitive detection at the single particle or molecular level. Noble metal nanoparticles of gold (Au) and silver (Ag) exhibit excellent plasmonic properties and have been applied for the selective and label-free detection of very low concentrations of aquatic pollutants. The present review represent the progress made towards the development and application of plasmonic nanosensors, specifically gold and silver nanoparticle-based sensors for the detection and quantification of various pollutants and contaminations in water. The design and fabrication of plasmonic nanosensors were given emphasis as it is fundamental in enhancing their affinity towards specific pollutant of interest. The effectiveness of plasmonic sensors in reducing the use of expensive instruments while enabling on-site multifunctional detection of toxin contaminants and also the future potential of plasmonic sensors will be highlighted.     

A nonenzymatic electrochemical sensor for the detection of hydrogen peroxide in vitro and in vivo fibrosis models

Fibrosis occurs due to the excessive deposition of extracellular matrix caused by cell injury. After various types of tissue injury, the dysregulation of the internal response can eventually lead to the destruction of organ structure and dysfunction. There is increasing evidence that oxidative stress, which is characterized by excessive production of hydrogen peroxide(H₂O₂), is an important cause of fibrosis. Therefore, we synthesized a biosensitive and efficient electroche...     

In vivo magnetic resonance detection of cancer by using multifunctional magnetic nanocrystals

The unique properties of magnetic nanocrystals provide them with high potential as key probes and vectors in the next generation of biomedical applications. Although superparamagnetic iron oxide nanocrystals have been extensively studied as excellent magnetic resonance imaging (MRI) probes for various cell trafficking, gene expression, and cancer diagnosis, further development of in vivo MRI applications has been very limited. Here, we describe in vivo diagnosis of cancer, utilizing a well-defined magnetic nanocrystal probe system with multiple capabilities, such as small size, strong magnetism, high biocompatibility, and the possession of active functionality for desired receptors. Our magnetic nanocrystals are conjugated to a cancer-targeting antibody, Herceptin, and subsequent utilization of these conjugates as MRI probes has been successfully demonstrated for the monitoring of in vivo selective targeting events of human cancer cells implanted in live mice. Further conjugation of these nanocrystal probes with fluorescent dye-labeled antibodies enables both in vitro and ex vivo optical detection of cancer as well as in vivo MRI, which are potentially applicable for an advanced multimodal detection system. Our study finds that high performance in vivo MR diagnosis of cancer is achievable by utilizing improved and multifunctional material properties of iron oxide nanocrystal probes.     

In silico models for the prediction of dose-dependent human hepatotoxicity

The liver is extremely vulnerable to the effects of xenobiotics due to its critical role in metabolism. Drug-induced hepatotoxicity may involve any number of different liver injuries, some of which lead to organ failure and, ultimately, patient death. Understandably, liver toxicity is one of the most important dose-limiting considerations in the drug development cycle, yet there remains a serious shortage of methods to predict hepatotoxicity from chemical structure. We discuss our latest findings in this area and present a new, fully general in silico model which is able to predict the occurrence of dose-dependent human hepatotoxicity with greater than 80% accuracy. Utilizing an ensemble recursive partitioning approach, the model classifies compounds as toxic or non-toxic and provides a confidence level to indicate which predictions are most likely to be correct. Only 2D structural information is required and predictions can be made quite rapidly, so this approach is entirely appropriate for data mining applications and for profiling large synthetic and/or virtual libraries.