Melanin-dependent tissue interactions induced by a 755-nm picosecond-domain laser: complementary visualization by optical imaging and histology.

Fractional picosecond-domain lasers (PSL) induce optical breakdown, which correlates histologically to vacuolization in the epidermis and dermis. In this ex vivo porcine study, we sought to establish a framework for the investigation of laser-tissue interactions and their dependence on melanin density. Light- (melanin index: 24.5 [0-100]), medium- (58.7), and dark-pigmented (> 98) porcine skin samples were exposed to a 755-nm fractional PSL and examined with dermoscopy, line-field confocal optical coherence tomography (LC-OCT), conventional OCT, and subsequently biopsied for digitally stained ex vivo confocal microscopy (EVCM) and histology, using hematoxylin and eosin (HE) and Warthin-Starry (WS) melanin staining. Dermoscopy showed focal whitening in medium- and dark-pigmented skin. Similarly, LC-OCT and OCT visualized melanin-dependent differences in PSL-induced tissue alterations. Vacuoles were located superficially in the epidermis in dark-pigmented skin but at or below the dermal-epidermal junction in medium-pigmented skin; in light-pigmented skin, no vacuoles were observed. Histology confirmed the presence of vacuoles surrounded by areas void of WS staining and disrupted stratum corneum in darker skin. The combined use of optical imaging for multiplanar visualization and histological techniques for examination of all skin layers may mitigate the effect of common artifacts and attain a nuanced understanding of melanin-dependent laser-tissue interactions.

Differential synthetic illumination based on multi-line detection for resolution and contrast enhancement of line confocal microscopy.

Line confocal (LC) microscopy is a fast 3D imaging technique, but its asymmetric detection slit limits resolution and optical sectioning. To address this, we propose the differential synthetic illumination (DSI) method based on multi-line detection to enhance the spatial resolution and optical sectioning capability of the LC system. The DSI method allows the imaging process to simultaneously accomplish on a single camera, which ensures the rapidity and stability of the imaging process. DSI-LC improves X- and Z-axis resolution by 1.28 and 1.26 times, respectively, and optical sectioning by 2.6 times compared to LC. Furthermore, the spatially resolved power and contrast are also demonstrated by imaging pollen, microtubule, and the fiber of the GFP fluorescence-labeled mouse brain. Finally, Video-rate imaging of zebrafish larval heart beating in a 665.6 × 332.8 µm2 field-of-view is achieved. DSI-LC provides a promising approach for 3D large-scale and functional imaging in vivo with improved resolution, contrast, and robustness.

A simple and low-cost method to visualize musculature and other aspects of anatomy by confocal microscopy.

Confocal microscopy study of musculature and other anatomical structures in whole-mount preparations of arthropods and some other cuticle-bearing animals often presents a significant difficulty because the cuticle poses a barrier to fluorescent dyes and their pigmented tissues can cause attenuation of fluorescent signal. This paper describes a simple and inexpensive procedure based on the use of clove oil as a tissue-clearing, staining, and mounting medium that helps overcome the problem of slow dye penetration and tissue opaqueness and allows muscles and several other organ systems to be visualized by confocal or epifluorescent microscopy. This clove oil-induced fluorescence (COIF) method relies on the ability of clove oil to accumulate in muscles and some other tissues and become steadily fluorescent if irradiated at 488 nm. For this method, animals were fixed in 70% ethanol or 4% formaldehyde, then dehydrated and mounted in clove oil. Heavily pigmented animals were additionally bleached in hydrogen peroxide prior to the dehydration step. The COIF method showed excellent results in all major groups of arthropods and some mollusks and annelids revealing the three-dimensional arrangement of muscles, gonads, glands, cellular nuclei and some parts of the nervous and digestive systems. In the other animal groups tested, clove oil stained all tissues making it difficult to observe the anatomical details. The COIF method is advantageous in some respects over other methods such as phalloidin staining because of its tissue penetration and clearing abilities, low cost of the reagents, resistance to photodamage and the possibility of staining museum specimens.

Holistic approach to visualize and quantify collagen organization at macro, micro, and nano-scale.

BACKGROUND: There is scarcity of imaging and image processing techniques for accurate discrimination and quantitation of the dermal extracellular matrix (ECM), primarily collagen. The aim of this study was to develop and demonstrate a holistic imaging and image processing approach to visualize and quantify collagen remodeling at the macro-, micro- and nano-scale using histochemical imaging, Reflectance Confocal Microscopy (RCM), and Atomic Force Microscopy (AFM), respectively. MATERIAL AND METHODS: For proof-of-concept, a commercial anti-aging product known to induce collagen neo-synthesis and re-organization was tested ex vivo on human skin biopsies from two aged females. RESULTS: Relative to untreated skin, collagen fibers (RCM) and fibrils (AFM) were longer and aligned after treatment. The content of collagen and elastin (histochemical imaging and ELISA) statistically improved after treatment. CONCLUSION: Based on our findings, we can conclude: (1) AFM, RCM, and histochemical imaging can accurately discriminate collagen from other ECM components in the skin and (2) the image processing methods can enable quantitation and hence capture small improvements in collagen remodeling after treatment (commercial cosmetic product with collagen organizer technology as proof-of-concept). The reported holistic imaging approach has direct clinical implications for scientists and dermatologists to make quick, real-time, and accurate decisions in skin research and diagnostics.

The effect of charge-balanced transcutaneous electrical nerve stimulation on rodent facial nerve regeneration.

This study aimed to investigate the effect of charge-balanced transcutaneous electrical nerve stimulation (cb-TENS) in accelerating recovery of the facial function and nerve regeneration after facial nerve (FN) section in a rat model. The main trunk of the left FN was divided and immediately sutured just distal to the stylomastoid foramen in 66 Sprague-Dawley rats. The control group had no electrical stimulus. The other two groups received cb-TENS at 20 Hz (20 Hz group) or 40 Hz (40 Hz group). Cb-TENS was administered daily for seven days and then twice a week for three weeks thereafter. To assess the recovery of facial function, whisker movement was monitored for four weeks. Histopathological evaluation of nerve regeneration was performed using transmission electron microscopy (TEM) and confocal microscopy with immunofluorescence (IF) staining. In addition, the levels of various molecular biological markers that affect nerve regeneration were analyzed. Whisker movement in the cb-TENS groups showed faster and better recovery than the control group. The 40 Hz group showed significantly better movement at the first week after injury (p < 0.0125). In histopathological analyses using TEM, nerve axons and Schwann cells, which were destroyed immediately after the injury, recovered in all groups over time. However, the regeneration of the myelin sheath was remarkably rapid and thicker in the 20 Hz and 40 Hz groups than in the control group. Image analysis using IF staining showed that the expression levels of S100B and NF200 increased over time in all groups. Specifically, the expression of NF200 in the 20 Hz and 40 Hz groups increased markedly compared to the control group. The real-time polymerase chain reaction was performed on ten representative neurotrophic factors, and the levels of IL-1ß and IL-6 were significantly higher in the 20 and 40 Hz groups than in the control group (p < 0.015). Cb-TENS facilitated and accelerated FN recovery in the rat model, as it significantly reduced the recovery time for the whisker movement. The histopathological study and analysis of neurotrophic factors supported the role of cb-TENS in the enhanced regeneration of the FN.

Squamous cell carcinoma: 2021 updated review of treatment.

Squamous cell carcinoma is the second most common cutaneous malignancy, requiring early diagnosis to prevent metastasis. Updated guidelines in the definition of clinical features, diagnostic modalities, grading, staging, surgical, and nonsurgical treatment methods are necessary. Diagnostic methods from biopsy, dermoscopy, and reflectance confocal microscopy have improved to include high-frequency ultrasonography, optical coherence tomography, and computed tomography. Non-surgical treatment methods include topical therapy, cryosurgery, photodynamic therapy, and radiation. Surgical treatment methods include surgical excision with margins and Mohs surgery. Clinical trials encourage further research to address the knowledge base of genetic variations and lymph node metastasis.

Endotelitis por citomegalovirus y su diagnóstico mediante la microscopia confocal / Cytomegalovirus endotheliitis and its diagnosis by confocal microscopy

Objetivo: Describir las características del endotelio corneal por microscopia confocal en pacientes con lesiones basofílicas de inclusión como patognomónicas de endotelitis por citomegalovirus. Métodos: Se realizó un estudio observacional de casos clínicos en pacientes con diagnóstico de endotelitis por citomegalovirus, atendidos en la Consulta de Córnea del Instituto Cubano de Oftalmología "Ramón Pando Ferrer", entre febrero del año 2010 y junio del 2018. La muestra incluyó 39 pacientes con diagnóstico clínico de endotelitis, a quienes se les realizó microscopia confocal con el equipo Confoscan 4 (Nidek Technologies). Resultados: De los 39 pacientes, 29 fueron del sexo masculino y 10 del femenino. Todos tenían entre 41 y 60 años de edad. En el 97,4 por ciento de los casos existió el antecedente de una conjuntivitis viral y un solo paciente fue positivo de HIV (2,6 por ciento). La mejor agudeza visual corregida de 0,3 o menos se mostró en el 100 por ciento de ellos antes del tratamiento, y después de este los 39 tenían entre 0,8 y 1,0. En el 100 por ciento de los casos se observaron cuerpos de inclusión basofílicos en el endotelio corneal, que fueron apreciables mediante la microscopia confocal. Conclusiones: Existe una relación entre la presencia de cuerpos de inclusión basofílicos en el endotelio corneal y las pruebas virológicas a citomegalovirus positivas, lo que puede permitir hacer PCR a casos que ya tienen confirmación mediante microscopia confocal de las características patognomónicas del endotelio corneal(AU)

Objective: Describe the characteristics of the corneal endothelium by confocal microscopy in patients with inclusion basophilic lesions as pathognomonic signs of cytomegalovirus endotheliitis. Methods: An observational study was conducted of clinical cases of patients diagnosed with cytomegalovirus endotheliitis attending the Cornea Service at Ramón Pando Ferrer Cuban Institute of Ophthalmology from February 2010 to June 2018. The study sample was 39 patients with a clinical diagnosis of endotheliitis who underwent confocal microscopy with a Confoscan 4 device (Nidek Technologies). Results: Of the 39 patients examined, 29 were male and 10 were female. All were aged 41-60 years. 97.4 percent had a history of viral conjunctivitis and only one was HIV positive (2.6 percent). Best corrected visual acuity was 0.3 or less in 100 percent before treatment, and 0.8 to 1.0 after treatment. Inclusion basophilic bodies visible by confocal microscopy were observed in the corneal endothelium of all patients. Conclusions: A relationship exists between the presence of inclusion basophilic bodies in the corneal endothelium and virological tests positive for cytomegalovirus, making it possible to perform PCR testing in cases with confocal microscopy confirmation of the pathognomonic characteristics of the corneal endothelium(AU)

Confocal hyperspectral microscopic imager for the detection and classification of individual microalgae.

We propose a confocal hyperspectral microscopic imager (CHMI) that can measure both transmission and fluorescent spectra of individual microalgae, as well as obtain classical transmission images and corresponding fluorescent hyperspectral images with a high signal-to-noise ratio. Thus, the system can realize precise identification, classification, and location of microalgae in a free or symbiosis state. The CHMI works in a staring state, with two imaging modes, a confocal fluorescence hyperspectral imaging (CFHI) mode and a transmission hyperspectral imaging (THI) mode. The imaging modes share the main light path, and thus obtained fluorescence and transmission hyperspectral images have point-to-point correspondence. In the CFHI mode, a confocal technology to eliminate image blurring caused by interference of axial points is included. The CHMI has excellent performance with spectral and spatial resolutions of 3 nm and 2 µm, respectively (using a 10× microscope objective magnification). To demonstrate the capacity and versatility of the CHMI, we report on demonstration experiments on four species of microalgae in free form as well as three species of jellyfish with symbiotic microalgae. In the microalgae species classification experiments, transmission and fluorescence spectra collected by the CHMI were preprocessed using principal component analysis (PCA), and a support vector machine (SVM) model or deep learning was then used for classification. The accuracy of the SVM model and deep learning method to distinguish one species of individual microalgae from another was found to be 96.25% and 98.34%, respectively. Also, the ability of the CHMI to analyze the concentration, species, and distribution differences of symbiotic microalgae in symbionts is furthermore demonstrated.

Identification of the suprachiasmatic nucleus venous portal system in the mammalian brain.

There is only one known portal system in the mammalian brain - that of the pituitary gland, first identified in 1933 by Popa and Fielding. Here we describe a second portal pathway in the mouse linking the capillary vessels of the brain's clock suprachiasmatic nucleus (SCN) to those of the organum vasculosum of the lamina terminalis (OVLT), a circumventricular organ. The localized blood vessels of portal pathways enable small amounts of important secretions to reach their specialized targets in high concentrations without dilution in the general circulatory system. These brain clock portal vessels point to an entirely new route and targets for secreted SCN signals, and potentially restructures our understanding of brain communication pathways.

Cytomembrane visualization using Stokes parameter confocal microscopy.

A new, to the best of our knowledge, method for Stokes vector imaging is proposed to achieve imaging and dynamic monitoring of a non-labeled cytomembrane. In this work, a polarization state vector is described by a Stokes vector and expressed in chrominance space. A physical quantity called polarization chromaticity value (PCV) corresponding to a Stokes vector is used as the imaging parameter to perform Stokes vector imaging. By using the PCV imaging technique, the Stokes vector can be expressed in three-dimensional real space rather than in a Poincare sphere. Furthermore, a four-way Stokes parameter confocal microscopy system is designed to measure four Stokes parameters simultaneously and obtain micro-imaging. Label-free living onion cell membranes and their plasmolysis process are selected as the representative micro-anisotropy experimental analysis. It is proved that PCV imaging can perform visualization of cytomembranes, and further, microscopic orientation is demonstrated. The prospect of universal measurement of anisotropy details for analysis and diagnosis is provided.

Upper digestion fate of citrus pectin-stabilized emulsion: An interfacial behavior perspective.

Citrus pectin can serve as a naturally digestion-resistant emulsifier, although how it achieves this effect is still unknown. In this study, the upper digestion fate of an emulsion stabilized by different concentrations of citrus pectin, and changes in its interfacial properties during digestion, were investigated. Emulsions stabilized by high-concentration citrus pectin (3 %) were relatively stable during digestion and had a lower free fatty acid (FFA) release rate than emulsions stabilized by low-concentration citrus pectin (1 %). At the low concentration, the citrus pectin interface had a thin absorbing layer and was largely replaced by bile salts, while at high concentration the citrus pectin interface possessed a uniform and thick adsorbing layer that resisted the replacement of bile salts and enabled lipase adsorption. This study has improved our understanding of the digestion of emulsion from the interface and will be useful for designing emulsion-based functional foods that can achieve targeted release.

Protective effect of Catharanthus roseus plant extracts against endosulfan and its isomers induced impacts on non-targeted insect model, Drosophila melanogaster and live brain cell imaging.

Endosulfan has been recognized as a highly controversial pesticide due to its acute toxicity, potential bioaccumulation, persistency, and long-range atmospheric transport. Several plant extracts act as antioxidant agents against wide-range of pesticide toxicity hazards through the free radicals scavenging properties. Plants' secondary metabolites are considered as efficient protective agents against various cellular toxic injuries. Understanding these properties of botanicals, several researchers currently focused on the detoxification and ameliorative potency of plant extracts against highly toxic chemicals. In our studies, we focused on the endosulfan total and its isomers (alpha and beta) induced changes on Drosophila melanogaster and their ameliorative effects by co-administrated with methanolic and aqueous extracts of Catharanthus roseus whole plant. We selected the 1/5th EC50 concentration of alpha-endosulfan, beta-endosulfan, and endosulfan (total) and co-administrated with 1/50th EC50 concentration of aqueous and methanolic extracts and evaluated their ameliorative effects, in terms of verifying the life stage activities, protein profiling and also by using live brain cells imaging. We finally concluded that, the methanolic and aqueous extracts inhibit the toxic impacts caused by endosulfan and its isomers and also increasing the survival rate of the test organism.

Broad-spectrum treatment of bacterial biofilms using magneto-responsive liquid metal particles.

The formation and proliferation of bacterial biofilms on surfaces, particularly those on biomedical devices, is a significant issue that results in substantial economic losses, presenting severe health risks to patients. Furthermore, heterogeneous biofilms consisting of different bacterial species can induce the increase in pathogenicity, and the resistance to antimicrobial agents due to the synergistic interactions between the different species. Heterogeneous bacterial biofilms are notoriously difficult to treat due to the presence of extracellular polymeric substances (EPS) and, in conjunction with the rapid rise of multi-drug resistant pathogens, this means that new solutions for anti-biofilm treatment are required. In this study, we investigate the application of magneto-responsive gallium-based liquid metal (GLM-Fe) nanomaterials against a broad range of Gram-positive and Gram-negative bacterial mono-species and multi-species biofilms. The GLM-Fe particles exhibit a magneto-responsive characteristic, causing spherical particles to undergo a shape transformation to high-aspect-ratio nanoparticles with sharp asperities in the presence of a rotating magnetic field. These shape-transformed particles are capable of physically removing bacterial biofilms and rupturing individual cells. Following treatment, both mono-species and multi-species biofilms demonstrated significant reductions in their biomass and overall cell viability, demonstrating the broad-spectrum application of this antibacterial technology. Furthermore, the loss of integrity of the bacterial cell wall and membranes was visualized using a range of microscopy techniques, and the leakage of intracellular components (such as nucleic acids and protein) was observed. Insights gained from this study will impact the design of future liquid metal-based biofilm treatments, particularly those that rely on magneto-responsive properties.

Calcium-cation-doped polydopamine-modified 2D black phosphorus nanosheets as a robust platform for sensitive and specific biomolecule sensing.

Many polymer decorated/modified 2D nanomaterials have been developed as enhanced drug delivery systems and photothermal theranostic nanoagents. However, few reports describe the use of these novel nanomaterials as nanoplatforms for biomolecule sensing. Herein, we used calcium-cation-doped polydopamine-modified (PDA-modified) 2D black phosphorus (BP) nanosheets (BP@PDA) as a sensing nanoplatform for the detection of nucleic acids and proteins in complex biological samples. Fluorescent-dye-labeled single-strand DNA aptamer/probes are adsorbed by the Ca2+-doped BP@PDA mediated by calcium-cation coordination. The PDA coating enhances the stability of the inner BP, provides binding sites to DNA nucleobases, and quenches fluorescence. Without any chemical conjugation, this sensing nanoplatform selectively and specifically detects protein (human thrombin, linear range: 10-25 nM, detection limit: 0.02 nM), single-strand DNA (linear range: 1-10 nM, detection limit: 0.52 nM) in 1% serum diluted samples, and senses intracellular mRNAs (C-myc, and actin) in living cells. The nanoplatform exhibits the advantages of both the 2D nanomaterial (BP) and the coating polymer (PDA), naturally enters living cells unaided by transfection agents, resists enzymatic lysis and shows high biocompatibility. This nanoplatform design contributes towards future biomolecule analytical method development based on polymer decorated/modified 2D nanomaterials.

Influence of alumina air-abrasion for highly translucent partially stabilized zirconia on flexural strength, surface properties, and bond strength of resin cement.

OBJECTIVE: This study aims to evaluate the influence of different air-abrasion pressures and subsequent heat treatment on the flexural strength, surface roughness, and crystallographic phases of highly translucent partially stabilized zirconia (Y-PSZ), and on the tensile bond strength of resin cement to Y-PSZ. METHODOLOGY: Fully sintered zirconia specimens were ground with SiC paper (control) and/or air-abraded with 50 µm particles of alumina at 0.1, 0.15, 0.2, or 0.3 MPa or left as-sintered. After air-abrasion at 0.2 MPa (0.2AB), additional specimens were then heated to 1500°C, and held for one hour at this temperature (0.2AB+HT1h). Flexural strength and surface roughness were evaluated. Crystalline phase identification was also carried out using X-ray diffraction. Bonded zirconia specimens with self-adhesive resin cement were stored in distilled water at 37°C for 24 h, either with or without aging (thermal cycling 4-60°C/20000). Results were analyzed statistically by ANOVA and Tukey-Kramer tests. RESULTS: The flexural strength decreased with the increase in air-abrasion pressure, while in contrast, the surface roughness increased. The lowest flexural strength and the highest roughness value were found for the 0.2AB and 0.3AB groups, respectively. All groups contained cubic-, tetragonal ( t )-, and rhombohedral ( r )-ZrO2 phases with the exception of the as-sintered group. Upon increasing the air-abrasion pressure, the relative amount of the r -ZrO2 phase increased, with a significant amount of r -ZrO2 phase being detected for the 0.2AB and 0.3AB groups. The 0.2AB+HT1h group exhibited a similar flexural strength and t -ZrO2 phase content as the as-sintered group. However, the 0.2AB group showed a significantly higher tensile bond strength (p<0.05) than the 0.2AB+HT1h group before and after aging. CONCLUSION: Micromechanical retention by alumina air-abrasion at 0.2 MPa, in combination with chemical bonding of a resin to highly translucent Y-PSZ using a MDP-containing resin cement may enable durable bonding.

Donor-acceptor conjugated polymer-based nanoparticles for highly effective photoacoustic imaging and photothermal therapy in the NIR-II window.

We prepared novel conjugated polymer based NIR-II nanoparticles, which display extremely high photothermal conversion efficiency (65%). Both in vitro and in vivo investigations revealed that the as-prepared nanoparticles exhibit excellent theranostic properties including an extremely high cancer cell killing ability, admirable tumor elimination efficiency (100%) and a remarkable photoacoustic imaging contrast enhancing ability.

In vivo two-photon imaging of neuronal and brain vascular responses in mice chronically exposed to ethanol.

The effects of ethanol on brain function have been extensively studied using a variety of in vitro and in vivo techniques. For example, electrophysiological studies using brain slices from rodents and non-human primates have demonstrated that acute and chronic exposure to ethanol alters the intrinsic excitability and synaptic signaling of neurons within cortical and sub-cortical areas of the brain. In humans, neuroimaging studies reveal alterations in measures of brain activation and connectivity in subjects with alcohol use disorder. While complementary, these methods are inherently limited due to issues related to either disruption of normal sensory input (in vitro slice studies) or resolution (whole brain imaging). In the present study, we used 2-photon laser scanning microscopy in intact animals to assess the impact of chronic ethanol exposure on sensory-evoked neuronal and vascular responses. Adult male C57BL/6J mice were exposed to four weekly cycles of chronic intermittent ethanol (CIE) exposure, while control mice were exposed to air. After withdrawal (≥72 h), a cranial window was placed over the primary visual cortex (V1), and sensory-evoked responses were monitored using the calcium indicator OGB-1. CIE exposure produced small but significant changes in response amplitude (decrease) and orientation selectivity of V1 neurons (increase). While arteriole diameter did not differ between control and CIE mice under baseline conditions, sensory-evoked dilation was enhanced in vessels from CIE-exposed mice as compared to controls. This was accompanied by a reduced latency in response to stimulation. In separate experiments, pial arteriole diameter was measured in the barrel cortex of control and CIE-exposed mice. Baseline diameter of barrel cortex arterioles was similar between control and CIE-exposed mice, but unlike vessels in V1, sensory-evoked dilation of barrel cortex arterioles was similar between the two groups. Together, the results of these studies suggest that chronic exposure to alcohol induces changes in neurovascular coupling that are region-dependent.

Influence of alumina air-abrasion for highly translucent partially stabilized zirconia on flexural strength, surface properties, and bond strength of resin cement

Abstract Objective This study aims to evaluate the influence of different air-abrasion pressures and subsequent heat treatment on the flexural strength, surface roughness, and crystallographic phases of highly translucent partially stabilized zirconia (Y-PSZ), and on the tensile bond strength of resin cement to Y-PSZ. Methodology Fully sintered zirconia specimens were ground with SiC paper (control) and/or air-abraded with 50 µm particles of alumina at 0.1, 0.15, 0.2, or 0.3 MPa or left as-sintered. After air-abrasion at 0.2 MPa (0.2AB), additional specimens were then heated to 1500°C, and held for one hour at this temperature (0.2AB+HT1h). Flexural strength and surface roughness were evaluated. Crystalline phase identification was also carried out using X-ray diffraction. Bonded zirconia specimens with self-adhesive resin cement were stored in distilled water at 37°C for 24 h, either with or without aging (thermal cycling 4-60°C/20000). Results were analyzed statistically by ANOVA and Tukey-Kramer tests. Results The flexural strength decreased with the increase in air-abrasion pressure, while in contrast, the surface roughness increased. The lowest flexural strength and the highest roughness value were found for the 0.2AB and 0.3AB groups, respectively. All groups contained cubic-, tetragonal ( t )-, and rhombohedral ( r )-ZrO2 phases with the exception of the as-sintered group. Upon increasing the air-abrasion pressure, the relative amount of the r -ZrO2 phase increased, with a significant amount of r -ZrO2 phase being detected for the 0.2AB and 0.3AB groups. The 0.2AB+HT1h group exhibited a similar flexural strength and t -ZrO2 phase content as the as-sintered group. However, the 0.2AB group showed a significantly higher tensile bond strength (p<0.05) than the 0.2AB+HT1h group before and after aging. Conclusion Micromechanical retention by alumina air-abrasion at 0.2 MPa, in combination with chemical bonding of a resin to highly translucent Y-PSZ using a MDP-containing resin cement may enable durable bonding.

Nitrogen, phosphorus and sulfur tri-doped carbon dots are specific and sensitive fluorescent probes for determination of chromium(VI) in water samples and in living cells.

A rapid, sensitive, and selective fluorometric assay is described for the determination of chromium(VI) in real waters and living cells. The method is making use of nitrogen, phosphorus, and sulfur tri-doped carbon dots (NPS-CDs) which have absorption/emission maxima at 360/505 nm/nm. Cr(VI) has an absorption maximum at 350 nm and causes an inner filter effect (IFE) on the blue fluorescence of the NPS-CDs. The NPS-CDs were hydrothermally synthesized using p-aminobenzenesulfonic acid and tetrakis(hydroxymethyl)phosphonium chloride as precursors. The NPS-CDs were characterized by transmission electron microscopy, X-ray diffraction, and several spectroscopic methods. They are biocompatible and negligibly cytotoxic when tested with HeLa cells and MCF-7 cells even after 48 h of incubation. The NPS-CDs were used as fluorescent probes for Cr(VI). The detection limit is 0.23 µM (three times standard deviation versus slope), and the linear response covers the 1 to 500 µM chromate concentration range. The NPS-CDs were applied to the determination of Cr(VI) in real waters and living cells (HeLa and MCF-7) and gave satisfying results. Graphical abstractSchematic representation of hydrothermal synthesis of nitrogen, phosphorus, and sulfur tri-doped carbon dots (NPS-CDs) for Cr(VI) detection via inner filter effect (IFE). NPS-CDs were applied to the determination of Cr(VI) in living cells (HeLa and MCF-7) with satisfying results.

Green synthesis of up- and down-conversion photoluminescent carbon dots from coffee beans for Fe3+ detection and cell imaging.

Carbon dots (CDs) are a developing stable, conductive, and environmentally friendly fluorescent nanomaterial with potential applications in biomedicine and sensing. In this study, CDs with up- and down-conversion photoluminescence characteristics were prepared via a one-pot hydrothermal method using coffee beans as the sole raw material. Fourier transform infrared spectra and X-ray photoelectron spectroscopy showed the presence of nitrogen and oxygen functional groups on the CDs surfaces. Transmission electron microscopy showed that the CDs were spherical with an average size of 4.6 nm. The CDs precursor and synthesis process are environmentally benign, and the resulting CDs exhibit excellent photostability, reversible fluorescence response to temperature, and good ionic-strength tolerance. Moreover, these CDs can be used as efficient fluorescence probes in selective and sensitive Fe3+ detection by a dual-readout assay. The down- and up-conversion fluorescence measurements from the CDs were in the linear range for 0-0.10 mM Fe3+ with the detection limits of 15.4 and 16.3 nM, respectively. Furthermore, the CDs were successfully applied to intracellular sensing and imaging Fe3+ ions, indicating their potential use in bioscience applications.