Microscope Attachment Research Articles

Rolosense: Mechanical Detection of SARS-CoV-2 Using a DNA-Based Motor.

Assays that detect viral infections play a significant role in limiting the spread of diseases such as SARS-CoV-2. Here, we present Rolosense, a virus sensing platform that leverages the motion of 5 μm DNA-based motors on RNA fuel chips to transduce the presence of viruses. Motors and chips are modified with aptamers, which are designed for multivalent binding to viral targets and lead to stalling of motion. Therefore, the motors perform a "mechanical test" of the viral target and stall in the presence of whole virions, which represents a unique mechanism of transduction distinct from conventional assays. Rolosense can detect SARS-CoV-2 spiked in artificial saliva and exhaled breath condensate with a sensitivity of 103 copies/mL and discriminates among other respiratory viruses. The assay is modular and amenable to multiplexing, as demonstrated by our one-pot detection of influenza A and SARS-CoV-2. As a proof of concept, we show that readout can be achieved using a smartphone camera with a microscopic attachment in as little as 15 min without amplification reactions. Taken together, these results show that mechanical detection using Rolosense can be broadly applied to any viral target and has the potential to enable rapid, low-cost point-of-care screening of circulating viruses.

Gagates in Crimean middle jurassic sediments (Sudak): coal petrography, paleobotany, formation conditions

Background. The coal-bearing deposits of the Kopsel formation of the Bathonian-Callovian age of the Middle Jurassic near the city of Sudak (Crimea) are studied. The conducted lithological and mineralogical analysis of rocks, mainly sandstones and siltstones, with shell detritus, plant residues and coal lenses (gagates), made it possible to determine the coastal-marine and lagoon sedimentation conditions. The studied gagates are represented by structural vitrinite and belong to the humus group. Secondary minerals in coal seams and host rocks indicate the stage of early catagenesis. The botanical analysis revealed the coal-forming plants, belonging to a group of conifers of the araucaria family.Aim. To identify the facies-climatic and landscape conditions for the formation of gagates of the Kopsel formation, along with their composition, structure, and secondary changes. To demonstrate that the material composition of coals is the wood of gymnosperms, mainly conifers, rather than algal thalli.Materials and methods. The natural outcrops of the coal-bearing deposits of the Middle Jurassic of the Bathonian-Callovian stage of the Kopsel formation in the valley of the Kopsel River near the city of Sudak (Crimea) were studied. The lenses and interlayers of brown coal — gagate — present in these deposits were of particular interest. Gagate samples were studied both macroscopically (forms and occurrence conditions in the section) and microscopically (by coal petrography methods). To this end, double-sided polished sections were examined using a polarizing microscope and a Vega3 Tescan scanning microscope. The microanalysis of chemical elements was performed using an ULTM Max (GIN) microscope attachment. Paleobotanical studies of carbonified plant residues were carried out. The structure, texture and mineral composition of the rocks were studied in thin sections using a microscope. A mineralogical analysis was carried out using a D8 Advace X-ray diffractometer (gross composition in a powder diffractogram and composition of clays in a fraction of <0.001 mm) and a Vega3 Tescan (GIN) scanning microscope.Results. The comprehensive studies conducted in the new, unique location of coals in the Kopsel Formation of the Middle Jurassic (Bathonian-Callovian stage) in the valley of the Kopsel River determined the paleobotanical composition of coal-forming plants (with the predominance of conifers of the Araucariaceae type), the climatic and paleolandscape conditions for the formation of these coals on the northern outskirts of Tethys. The lithological and mineralogical features of rocks, mainly sandstones and siltstones, with shell detritus, plant residues and lenses of coals (gagates), make it possible to determine the facies conditions of sedimentation as coastal-marine and lagoonal, with fragments of avantdelta and proluvial, landslide deposits. The established secondary changes in the host rocks and the coals indicate the stage of early catagenesis, to which the stratum was subjected at the next stages of geological history.Conclusion. Peat accumulation and subsequent coal formation most likely occurred in shallow lagoons. The type of peat accumulation is paralytic, paragenetically related to the studied sediments. Post-sedimentation transformations of the rocks correspond to early catagenesis. These transformations were established by the presence of secondary calcite (by rock cracks and in the form of nodule formations), the abundance of authigenic gypsum, and the widespread replacement of pyrite framboids with iron oxide minerals. The interlayers of gagates have also undergone changes. In those places where organic matter is impregnated with carbonate solutions, the coal substance is exposed to heat, thus becoming optically opaque.

Extraembryonic membrane morphology in greater rheas (Rhea americana americana Linnaeus, 1758).

The greater rhea, Rhea americana, is a wild ratite of high scientific importance and significant and zootechnical value, especially considering the current development state of Brazilian poultry production, where research aimed at increasing the productivity of these animals has become extremely relevant. Studies concerning fetal attachments and embryonic development are paramount, as they can provide essential information concerning reproductive and nutritional animal management. However, a lack of information on greater rhea fetal morphology is noted. Therefore, the aim of the present study was to establish a standard model for fetal attachments in this species. Greater rhea eggs were incubated from 0 to 36days, and macroscopic and microscopic embryonic attachment characterizations were performed. Histologically, all embryonic annexes exhibit germ layers, namely the ectoderm (outer layer), mesoderm (middle layer) and endoderm (inner layer). The findings indicate that greater rhea development patterns are similar to other birds.

A Novel Method for Teaching Laser Peripheral Iridotomy and Selective Laser Trabeculoplasty Using Video Instruction and Model Eyes

Abstract Objective The aim of the study is to describe an inexpensive and easily-constructed model eye for the purpose of teaching laser peripheral iridotomy (LPI) and selective laser trabeculoplasty (SLT) to ophthalmology residents. Methods Easily constructed, inexpensive model eyes were utilized to teach residents SLT and LPI utilizing a remote self-study module. A teaching microscope attachment allowed for video-based instruction and feedback. Results This model eye, used in conjunction with video modules is an effective low-cost teaching tool for laser surgery among ophthalmology residents. Attending ophthalmologists rated the use of these model eyes using surveys and found them to be appropriate teaching tools that could lead to improved knowledge and translate to better patient care. Conclusion Our novel method for teaching glaucoma laser surgery allows residents to learn the principles and theory behind common laser procedures while having the opportunity to practice repetitive procedures on low-cost model eyes.

Real-time confocal microscopy imaging of corneal cytoarchitectural changes induced by different stresses

Maintenance of the corneal refractive power and tissue transparency is essential for normal vision. Real-time characterization of changes in corneal cells during suffering stresses or wound healing may provide a way to identify novel targets, whose therapeutic manipulation can improve the outcome of this response induced by injury. Here we describe a novel user friendly and effective confocal real-time confocal microscopy attachment that monitors the effects of anisoosmotic stress on cell morphology and corneal thickness in situ. Corneal epithelial nuclei gradually became highly reflective in the isotonic group and the corneal stroma was slightly thickened as compared with that seen prior to 60 min exposure to a hypotonic solution. After 30 min of exposure to hypertonic stress, the corneal stromal cells became crenate and shriveled. The hyper-reflective area of the corneal stroma in the hypo-osmotic group was significantly larger than that in the other two groups, as demonstrated by 3D reconstruction imaging. The hypotonic fresh chlorinated pool water was observed to cause atrophy of corneal epithelial nuclei, while the isosmotic bee venom solution caused high reflection of the corneal stroma layer and corneal endothelial cell damage. With the microscopic attachment, the inward movement of corneal epithelial cells toward the denuded central region was detected in the serum-treated group. The microscopy attachment is an effective system for obtaining a more detailed understanding of the time dependent losses in the corneal cell structure and tissue architecture of full thickness corneas induced by osmotic stress or cytotoxic agents.

Mitigating the negative effects of feldspar slime on spodumene flotation using mixed anionic/cationic collector

Due to the prevalent weathering, spodumene flotation is often susceptible to feldspar slime. In this study, the effect of feldspar slime on spodumene flotation in the NaOL and NaOL/DDA systems was studied. The micro-flotation tests showed that the negative effect of feldspar slime on spodumene flotation could be reduced by using the mixed NaOL/DDA collector with mole ratio of 9/1. The scanning electron microscopic images and the adsorption test results indicated that the decrease of spodumene recovery was attributed to collector consumption by feldspar slime. The mechanism was analyzed by ways of surface tension measurement, atomic force microscopic (AFM) observation and bubble attachment measurements, and the results showed that compared with NaOL alone, the mixed NaOL/DDA collector exhibited a better surface activity owing to a lower value of critical micelle concentration (CMC). The ‘spots’ formed on spodumene surface were thicker, and the formation of TPC was more likely. In addition, the bubble size was smaller and the bubble–particle adhesion was more possibly to occur in the NaOL/DDA system.

A modular microscopic smartphone attachment for imaging and quantification of multiple fluorescent probes using machine learning.

Portable smartphone-based fluorescent microscopes are becoming popular owing to their ability to provide major functionalities offered by regular benchtop microscopes at a fraction of the cost. However, smartphone-based microscopes are still limited to a single fluorophore, fixed magnification, the inability to work with a different smartphones, and limited usability to either glass slides or cover slips. To overcome these challenges, here we present a modular smartphone-based microscopic attachment. The modular design allows the user to easily swap between different sets of filters and lenses, thereby enabling utility of multiple fluorophores and magnification levels. Our microscopic smartphone attachment can also be used with different smartphones and was tested with Nokia Lumia 1020, Samsung Galaxy S9+, and an iPhone XS. Further, we showed imaging results of samples on glass slides, cover slips, and microfluidic devices. A 1951 USAF resolution test target was used to quantify the maximum resolution of the microscope which was found to be 3.9 μm. The performance of the smartphone-based microscope was compared with a benchtop microscope and we found an R2 value of 0.99 using polystyrene beads and blood cells isolated from human blood samples collected from Robert Wood Johnson Medical Hospital. Additionally, to count the particles (cells and beads) imaged from the smartphone-based fluorescent microscope, we developed artificial neural networks (ANNs) using multiple training algorithms, and evaluated their performances compared to the control (ImageJ). Finally, we did ANOVA and Tukey's post-hoc analysis and found a p-value of 0.97 which shows that no statistical significant difference exists between the performance of the trained ANN and control (ImageJ).

Smartphone microscope in eye clinic to visualize fungus and Demodex

Purpose: Ophthalmologists often need to use a compound microscope to see slides of corneal scrapings, Demodex blepharitis, histopathology, or tear ferning test for diagnostic purposes. While such a microscope may be available in tertiary care centers, most eye clinics do not have it due to cost, space required, and infrequent use. These tests are often not done or delayed till a tertiary referral is possible. We demonstrate an alternative method using smartphone and an inexpensive attachment. Materials and Methods: Using the smartphone microscope attachment, the authors were able to capture excellent photographs and videos of corneal scrapings, histopathology, and Demodex. Photographs of the same slides were taken with a standard compound microscope as well. Trypan blue dye was used for staining the corneal scraping specimens to make the fungal hyphae in it clearly visible. Results: Photographs and videos captured by the smartphone microscope were compared with those from a compound microscope and found to be of adequate quality. They were determined to be good enough for diagnostic use. Conclusions: We determined that smartphone microscope attachment can be a useful adjunctive diagnostic tool for eye clinics corneal scrapings, histopathology, and Demodex, perhaps even for more applications.

Evaluation and comparison between smartphone and photomicrography based whole slide imaging.

Context:In recent years, a new concept has emerged at the forefront of slide-based diagnosis and telepathology. This is the concept of whole slide imaging. This has very recently also been tried with smartphones using complex software for photo analysis and stitching. This study is aimed to evaluate and compare the use of Jenoptik photomicrograph camera and smartphone camera-based whole slide imaging (WSI) for various microscopic preparations and slides. The study also uses a commonly available IOS smartphone device, a commonly available phone to microscope attachment, and the most commonly used Adobe Photoshop software for all stitching purposes.Aim:To evaluate and compare smartphone and photomicrography-based whole slide imaging.Subjects and Methods:The study was conducted at the Department of Oral Pathology and Microbiology in Bapuji Dental College and Hospital, Davangere. The samples included in this study are 10 slides of routine hematoxylin and eosin stain slides and 10 ground section slides of teeth and bone samples. Continuous photographs of the entire slide were captured using an IOS device and a Jenoptik camera attached research microscope at 10× magnification. The photographs were stitched using Adobe Photoshop 2017 software to obtain a whole slide image. Then, two observers analyzed the whole slide image for a possible diagnosis and thus compared the efficiency of both the methods.Statistical Analysis Used:The statistical Chi-square test and analysis of variance (ANOVA) H test were done using Statistical Package for the Social Sciences (SPSS) 2010 Software.Results:Percentage of measure of agreement was 79.5%, 83.7% and 86.3%, 89.1% for the whole slide images taken in the smartphone and photomicrograph and analyzed by Observer 1 and Observer 2, respectively.Conclusions:In this study, it can be seen that the WSI by research microscopes is better than that with a smartphone and a compound microscope but still both the methods are equally good and can be followed with accurate results.

Simplified White Blood Cell Differential: An Inexpensive, Smartphone- and Paper-Based Blood Cell Count.

Sorting and measuring blood by cell type is extremely valuable clinically and provides physicians with key information for diagnosing many different disease states including: leukemia, autoimmune disorders, bacterial infections, etc. Despite the value, the present methods are unnecessarily costly and inhibitive particularly in resource poor settings, as they require multiple steps of reagent and/or dye additions and subsequent rinsing followed by manual counting using a hemocytometer, or they require a bulky, expensive equipment such as a flow cytometer. While direct on-paper imaging has been considered challenging, paper substrate offers a strong potential to simplify such reagent/dye addition and rinsing. In this work, three-layer paper-based device is developed to automate such reagent/dye addition and rinsing via capillary action, as well as separating white blood cells (WBCs) from whole blood samples. Direct onpaper imaging is demonstrated using a commercial microscope attachment to a smartphone coupled with a blue LED and 500 nm long pass optical filter. Image analysis is accomplished using an original MATLAB code, to evaluate the total WBC count, as well as differential WBC count, i.e., granulocytes (primarily neutrophils) vs. agranulocytes (primarily lymphocytes). Only a finger-prick of whole blood is required for this assay. The total assay time from finger-prick to data collection is under five minutes. Comparison with a hemocytometry-based manual counting corroborates the accuracy and effectiveness of the proposed method. This approach could be potentially used to help make blood cell counting technologies more readily available, especially in resource poor, point-of-care settings.

Kankanet: An artificial neural network-based object detection smartphone application and mobile microscope as a point-of-care diagnostic aid for soil-transmitted helminthiases.

BackgroundEndemic areas for soil-transmitted helminthiases often lack the tools and trained personnel necessary for point-of-care diagnosis. This study pilots the use of smartphone microscopy and an artificial neural network-based (ANN) object detection application named Kankanet to address those two needs.Methodology/Principal findingsA smartphone was equipped with a USB Video Class (UVC) microscope attachment and Kankanet, which was trained to recognize eggs of Ascaris lumbricoides, Trichuris trichiura, and hookworm using a dataset of 2,078 images. It was evaluated for interpretive accuracy based on 185 new images. Fecal samples were processed using Kato-Katz (KK), spontaneous sedimentation technique in tube (SSTT), and Merthiolate-Iodine-Formaldehyde (MIF) techniques. UVC imaging and ANN interpretation of these slides was compared to parasitologist interpretation of standard microscopy.Relative to a gold standard defined as any positive result from parasitologist reading of KK, SSTT, and MIF preparations through standard microscopy, parasitologists reading UVC imaging of SSTT achieved a comparable sensitivity (82.9%) and specificity (97.1%) in A. lumbricoides to standard KK interpretation (97.0% sensitivity, 96.0% specificity). The UVC could not accurately image T. trichiura or hookworm. Though Kankanet interpretation was not quite as sensitive as parasitologist interpretation, it still achieved high sensitivity for A. lumbricoides and hookworm (69.6% and 71.4%, respectively). Kankanet showed high sensitivity for T. trichiura in microscope images (100.0%), but low in UVC images (50.0%).Conclusions/SignificanceThe UVC achieved comparable sensitivity to standard microscopy with only A. lumbricoides. With further improvement of image resolution and magnification, UVC shows promise as a point-of-care imaging tool. In addition to smartphone microscopy, ANN-based object detection can be developed as a diagnostic aid. Though trained with a limited dataset, Kankanet accurately interprets both standard microscope and low-quality UVC images. Kankanet may achieve sensitivity comparable to parasitologists with continued expansion of the image database and improvement of machine learning technology.

The structure and nanomechanical properties of amorphous welds made at reduced temperature

Presently, elements made of Fe-based amorphous materials are characterised by small dimensions. The use of the laser welding process will make it possible to increase diameters of parts along with the enhanced applicability of modern materials. To obtain exceptional post-weld properties of a given material, its structure in the heat affected zone (HAZ), the fusion zone (FZ) and in the parent material (PM) should be controlled.An important issue accompanying the welding of bulk metallic glasses (BMGs) is chemical composition of the amorphous phase. The crystallisation process is the most common phenomenon occurring in the HAZ during the welding of iron-based amorphous materials. The essence of the solution to the crystallisation issue consists in the use of laser welding as well as in the application of a cooling system enabling the reduction of temperature. The article presents the crystallisation process and a new solution to the problem.The primary objective of this research work involved the laser welding of specimens at a reduced (sub-zero) temperature and the presentation of the structure and nanomechanical properties of amorphous welds.Because of the metastable nature of welded BMGs and due to the small dimensions of the FZ, a high-resolution transmission electron microscope and a triboindenter equipped with a microscopic attachment were used in structural and properties-related tests. A decrease in temperature of the material subjected to welding was obtained using a specifically designed cooling system based on Peltier modules.The examination of the weld nanostructure revealed that the laser welding of the amorphous material cooled to a temperature of −17 °C enabled the joining of elements without the occurrence of crystalline precipitation. Detailed research revealed the presence of the amorphous phase in the PM, FZ and HAZ.

The Use of a Special Stereoscopic Microscope Attachment for the Sieve Analysis of Aggregate in Concrete

The article proposes an innovative technique that allows relatively easy distinction of sand and aggregate particles on the surface image of a concrete specimen. The concept of the proposed approach involves the use of a new method of illuminating carefully polished surfaces of specimens. This is possible owing to a special attachment mounted on the lens of a stereoscopic microscope. The obtained digital image of the specimen, after being converted into a binary image, was subjected to a standard numerical analysis to determine the parameters characterizing the aggregate, i.e., particle size distribution (grading curve), maximum dimension, and shape. Two application examples are presented for analysing sand particle size and for determining the cement paste content in the concrete. The results obtained with the proposed technique were very promising and offer great potential for its practical implementation.

Novel millimeter-wave-based method for in situ cell isolation and other applications

As an alternative to laser-based methods, we developed a novel in situ cell isolation method and instrument based on local water absorption of millimeter wave (MMW) radiation that occurs in cellular material and nearby culture medium while the cultureware materials (plastic and glass) are transparent to MMW frequencies. Unwanted cells within cell population are targeted with MMWs in order to kill them by overheating. The instrument rapidly (within 2–3 seconds) heats a cell culture area of about 500 µm in diameter to 50 °C using a low-power W-band (94 GHz) MMW source. Heated cells in the area detach from the substrate and can be removed by a media change leaving a bare spot. Hence we named the instrument “CellEraser”. Quick, local and non-contact heating with sharp boundaries of the heated area allows elimination of the unwanted cells without affecting the neighboring cells. The instrument is implemented as a compact microscope attachment and the selective hyperthermic treatment can be done manually or in an automated mode. Mammalian cells heated even momentarily above 50 °C will not survive. This “temperature of no return” does not compromise cellular membranes nor does it denature proteins. Using the CellEraser instrument we found that the key event that determines the fate of a cell at elevated temperatures is whether or not the selectivity of its nucleus is compromised. If a cell nucleus becomes “leaky” allowing normally excluded (cytoplasmic) proteins in and normally nuclear-localized proteins out, that cell is destined to die. Quick heating by MMWs to higher temperatures (70 °C) denatures cellular proteins but the cells are not able to detach from the substrate – instead they undergo a phenomenon we called “thermofixation”: such cells look similar to cells fixed with common chemical fixatives. They remain flat and are not washable from the substrate. Interestingly, their membranes become permeable to DNA dyes and even to antibodies. Thermofixation allows the use of western blot antibodies for immunofluorescence imaging.

Microscope-Integrated Intraoperative Ultrahigh-Speed Swept-Source Optical Coherence Tomography for Widefield Retinal and Anterior Segment Imaging.

To demonstrate the feasibility of retinal and anterior segment intraoperative widefield imaging using an ultrahigh-speed, swept-source optical coherence tomography (SS-OCT) surgical microscope attachment. A prototype post-objective SS-OCT using a 1,050-nm wavelength, 400 kHz A-scan rate, vertical cavity surface-emitting laser (VCSEL) light source was integrated to a commercial ophthalmic surgical microscope after the objective. Each widefield OCT data set was acquired in 3 seconds (1,000 × 1,000 A-scans, 12 × 12 mm2 for retina and 10 × 10 mm2 for anterior segment). Intraoperative SS-OCT was performed in 20 eyes of 20 patients. In six of seven membrane peels and five of seven rhegmatogenous retinal detachment repair surgeries, widefield retinal imaging enabled evaluation pre- and postoperatively. In all seven cataract cases, anterior imaging evaluated the integrity of the posterior lens capsule. Ultrahigh-speed SS-OCT enables widefield intraoperative viewing in the posterior and anterior eye. Widefield imaging visualizes ocular structures and pathology without requiring OCT realignment. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:94-102.].

Integrated methodology for determining provenance of detrital quartz using optical petrographic microscopy and cathodoluminescence (CL) properties

The provenance of detrital quartz is a useful predictor in frontier basin sandstone reservoirs of the availability of coarse-grained quartz grains of plutonic or high grade metamorphic origin. The standard approach is to use scanning electron microscope (SEM) panchromatic cathodoluminescence (CL) imagery and observations from an optical petrographic microscope. We describe a work flow, modified from previous literature proposals, to determine quartz provenance in detrital grains using optical petrographic microscopy and CL properties from both a hot-cathode cathodoluminescence microscope attachment (HCMA) and panchromatic SEM-CL. HCMA analysis permits better discrimination of different types of metamorphic quartz. This method is applied to a Middle Jurassic to Lower Cretaceous section in the Bandol-1 wildcat well, located in the Laurentian sub-basin south of Newfoundland. Two types of high-grade metamorphic quartz are distinguished, one with low luminescence as described in previous literature and one with medium blue CL colour and a moderate colour shift that is also known from granulite in the hinterland. Three phases of detrital supply are identified, suggesting progressive unroofing of higher grade metamorphic sources through the middle Jurassic and major input of plutonic quartz in the early Cretaceous.

Investigation into the properties of parts face-hardened with alloying elements under conditions of self-propagating high-temperature synthesis

The structure and formation of diffusion SHS layers are investigated for high-carbon materials. Highcarbon materials of grades ASCh-1 (GOST (State Standard) 1585-85), SCh-20, SCh-25 (GOST 805-95), VCh 45-5, VCh 38-17, and VCh 42-12 (DSTU (State Standard of Ukraine) 3925-99); composition materials of grade UUKM based on an Ural NSh-215 carbon fabric; and electrode graphite EG were selected to study. The microstructure of the strengthened layer was studied using a Neophot-21 light microscope. The phase analysis is carried out using an MS-46 X-ray microanalyzer equipped with an ME 76 electron microscope attachment. Tests for heat resistance were performed according to GOST 6130-71, for adhesion according to the conical indenter pressing-in method, for wear resistance according to GOST 23.224-86, and for corrosion resistance by measuring the sample weight before and after tests. An ASTRA software package was used to compute the equilibrium composition of the system products.

Infrared reflectance spectroscopy as an analytical technique for the study of residues on stone tools: potential and challenges

FTIR (Fourier transform infrared) spectroscopy is a non-destructive analytical method that has been used successfully to analyse both inorganic and organic archaeological material. Using a microscope attachment has the additional benefit of analysing very small spots (diameter 100 μm) directly on an artefact without sample preparation or destruction. It is therefore a suitable method to study residues on prehistoric stone tools. However, using a microscope without an ATR (attenuated total reflection) microscope objective, results in a combination of reflection and transmission/absorbance FTIR spectra, which is not always as easy to interpret as directly measured transmission/absorbance spectra. In order to improve the interpretation of spectra recorded on archaeological samples, the method was tested with replicated Middle Stone Age stone points used during hunting and butchery experiments on parts of a blue wildebeest (Connochaetes taurinus) published in 2004 (Lombard et al., 2004). In this case, the residues on the tools were known and post-depositional contamination was eliminated. Additional samples of the organic materials, and the minerals from which the tools were made were also available. Therefore, we could assess the viability of FTIR reflectance spectra for distinguishing between bone, fat and protein residues.

Chitosan/alginate crosslinked hydrogels: Preparation, characterization and application for cell growth purposes

Chitosan hydrogels may be formed by various mechanisms. In this study, we aimed to form hybrid polymer networks of chitosan with alginate using a crosslinker which enabled the covalent binding of the two macromolecules. The structural and thermal characterization of these hydrogels was performed by using Fourier transform infrared (FTIR) and differential scanning calorimeter (DSC). The morphological analysis of the crosslinked material was investigated by scanning electron microscopy (SEM) and a scanning probe microscope with atomic force microscope (AFM) attachment. The swelling properties of these gels were analyzed in water and in phosphate buffered saline (PBS) solution. The presence of alginate in a chitosan/alginate hydrogel was shown to support the hydrogel stability. Compared to chitosan/alginate (1/2) hydrogel prepared with 1wt% DCC, the swelling of chitosan/alginate (1/2) hydrogels prepared with 3wt% DCC was limited. To measure the degree of cell proliferation, the hydrogels were seeded with L929 mouse fibroblasts and cell numbers measured by neutral red uptake assay. The cell attachment was also followed by (SEM) photography. It was observed that chitosan/alginate (1/2) hydrogels with 1wt% (DCC) provides a better environment for cell attachment and proliferation. This study presents functional hydrogel formation by crosslinked chitosan and alginate, a novel biomaterial which also supports cell growth.

Evaluation of the ParaLens<sup>TM</sup> LED microscope attachment versus standard fluorescence microscopy for detection of Mycobacteria

The ParalensTM (PL) microscope attachment converts a light microscope into an epi-fluorescencemicroscope. We compared the PL to standard fluorescence microscopy for detection ofMycobacteriain clinical and spiked samples. Overall agreement between the two systems was 100%. Quantitative and qualitative performance was comparable. The PL is an acceptable alternative to standard fluorescence microscopy for detection ofMycobacteria.