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Patel MA, Yang H, Chiu PL, Mastrogiovanni DDT, Flach CR, Savaram K, Gomez L, Hemnarine A, Mendelsohn R, Garfunkel E, Jiang H, He H. Direct production of graphene nanosheets for near infrared photoacoustic imaging. ACS NANO 2013; 7:8147-8157. [PMID: 24001023 DOI: 10.1021/nn403429v] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Hummers method is commonly used for the fabrication of graphene oxide (GO) from graphite particles. The oxidation process also leads to the cutting of graphene sheets into small pieces. From a thermodynamic perspective, it seems improbable that the aggressive, somewhat random oxidative cutting process could directly result in graphene nanosheets without destroying the intrinsic π-conjugated structures and the associated exotic properties of graphene. In Hummers method, both KMnO4 and NO2(+) (nitronium ions) in concentrated H2SO4 solutions act as oxidants via different oxidation mechanisms. From both experimental observations and theoretical calculations, it appears that KMnO4 plays a major role in the observed oxidative cutting and unzipping processes. We find that KMnO4 also limits nitronium oxidative etching of graphene basal planes, therefore slowing down graphene fracturing processes for nanosheet fabrication. By intentionally excluding KMnO4 and exploiting pure nitronium ion oxidation, aided by the unique thermal and kinetic effects induced by microwave heating, we find that graphite particles can be converted into graphene nanosheets with their π-conjugated aromatic structures and properties largely retained. Without the need of any postreduction processes to remove the high concentration of oxygenated groups that results from Hummers GO formation, the graphene nanosheets as-fabricated exhibit strong absorption, which is nearly wavelength-independent in the visible and near-infrared (NIR) regions, an optical property typical for intrinsic graphene sheets. For the first time, we demonstrate that strong photoacoustic signals can be generated from these graphene nanosheets with NIR excitation. The photo-to-acoustic conversion is weakly dependent on the wavelength of the NIR excitation, which is different from all other NIR photoacoustic contrast agents previously reported.
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Yu G, Zhang G, Flach CR, Mendelsohn R. Vibrational spectroscopy and microscopic imaging: novel approaches for comparing barrier physical properties in native and human skin equivalents. JOURNAL OF BIOMEDICAL OPTICS 2013; 18:061207. [PMID: 23165761 DOI: 10.1117/1.jbo.18.6.061207] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Vibrational spectroscopy and imaging have been used to compare barrier properties in human skin, porcine skin, and two human skin equivalents, Epiderm 200X with an enhanced barrier and Epiderm 200 with a normal barrier. Three structural characterizations were performed. First, chain packing and conformational order were compared in isolated human stratum corneum (SC), isolated porcine SC, and in the Epiderm 200X surface layers. The infrared (IR) spectrum of isolated human SC revealed a large proportion of orthorhombically packed lipid chains at physiological temperatures along with a thermotropic phase transition to a state with hexagonally packed chains. In contrast, the lipid phase at physiological temperatures in both porcine SC and in Epiderm 200X, although dominated by conformationally ordered chains, lacked significant levels of orthorhombic subcell packing. Second, confocal Raman imaging of cholesterol bands showed extensive formation of cholesterol-enriched pockets within the human skin equivalents (HSEs). Finally, IR imaging tracked lipid barrier dimensions as well as the spatial disposition of ordered lipids in human SC and Epiderm 200X. These approaches provide a useful set of experiments for exploring structural differences between excised human skin and HSEs, which in turn may provide a rationale for the functional differences observed among these preparations.
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Spevak L, Flach CR, Hunter T, Mendelsohn R, Boskey A. Fourier transform infrared spectroscopic imaging parameters describing acid phosphate substitution in biologic hydroxyapatite. Calcif Tissue Int 2013; 92:418-28. [PMID: 23380987 PMCID: PMC3631290 DOI: 10.1007/s00223-013-9695-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 12/14/2012] [Indexed: 12/13/2022]
Abstract
Acid phosphate substitution into mineralized tissues is an important determinant of their mechanical properties and their response to treatment. This study identifies and validates Fourier transform infrared spectroscopic imaging (FTIRI) spectral parameters that provide information on the acid phosphate (HPO4) substitution into hydroxyapatite in developing mineralized tissues. Curve fitting and Fourier self-deconvolution were used to identify subband positions in model compounds (with and without HPO4). The intensity of subbands at 1127 and 1110 cm(-1) correlated with the acid phosphate content in these models. Peak height ratios of these subbands to the ν3 vibration at 1096 cm(-1) found in stoichiometric apatite were evaluated in the model compounds and mixtures thereof. FTIRI spectra of bones and teeth at different developmental ages were analyzed using these spectral parameters. Factor analysis (a chemometric technique) was also conducted on the tissue samples and resulted in factor loadings with spectral features corresponding to the HPO4 vibrations described above. Images of both factor correlation coefficients and the peak height ratios 1127/1096 and 1112/1096 cm(-1) demonstrated higher acid phosphate content in younger vs. more mature regions in the same specimen. Maps of the distribution of acid phosphate content will be useful for characterizing the extent of new bone formation, the areas of potential decreased strength, and the effects of therapies such as those used in metabolic bone diseases (osteoporosis, chronic kidney disease) on mineral composition. Because of the wider range of values obtained with the 1127/1096 cm(-1) parameter compared to the 1110/1096 cm(-1) parameter and the smaller scatter in the slope, it is suggested that this ratio should be the parameter of choice.
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Mao G, VanWyck D, Xiao X, Mack Correa MC, Gunn E, Flach CR, Mendelsohn R, Walters RM. Oleic acid disorders stratum corneum lipids in Langmuir monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4857-4865. [PMID: 23517601 DOI: 10.1021/la4002384] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Oleic acid (OA) is well-known to affect the function of the skin barrier. In this study, the molecular interactions between OA and model stratum corneum (SC) lipids consisting of ceramide, cholesterol, and palmitic acid (PA) were investigated with Langmuir monolayer and associated techniques. Mixtures with different OA/SC lipid compositions were spread at the air/water interface, and the phase behavior was tracked with surface pressure-molecular area (π-A) isotherms. With increasing OA levels in the monolayer, the films became more fluid and more compressible. The thermodynamic parameters derived from π-A isotherms indicated that there are preferential interactions between OA and SC lipids and that films of their mixtures were thermodynamically stable. The domain structure and lipid conformational order of the monolayers were studied through Brewster angle microscopy (BAM) and infrared reflection absorption spectroscopy (IRRAS), respectively. Results indicate that lower concentrations of OA preferentially mix with and disorder the ceramide-enriched domains, followed by perturbation of the PA-enriched domains and disruption of SC lipid domain separation at higher OA levels.
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Mao G, VanWyck D, Xiao X, Gunn E, Flach CR, Mendelsohn R, Walters RM. Effects of Oleic Acid on Stratum Corneum Lipids in Langmuir Monolayers. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Yu G, Stojadinovic O, Tomic-Canic M, Flach CR, Mendelsohn R. Infrared microscopic imaging of cutaneous wound healing: lipid conformation in the migrating epithelial tongue. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:96009-1. [PMID: 23085910 DOI: 10.1117/1.jbo.17.9.096009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Infrared microscopic imaging has been utilized to analyze for the first time the spatial distribution of lipid structure in an ex vivo human organ culture skin wound healing model. Infrared images were collected at zero, two, four, and six days following wounding. Analysis of lipid infrared spectral properties revealed the presence of a lipid class with disordered chains within and in the vicinity of the migrating epithelial tongue. The presence of lipid ester C=O bands colocalized with the disordered chains provided evidence for the presence of carbonyl-containing lipid species. Gene array data complemented the biophysical studies and provided a biological rationale for the generation of the disordered chain species. This is the first clear observation, to our knowledge, of disordered lipid involvement in cutaneous wound healing. Several possibilities are discussed for the biological relevance of these observations.
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Mao G, Flach CR, Mendelsohn R, Walters RM. Imaging the distribution of sodium dodecyl sulfate in skin by confocal Raman and infrared microspectroscopy. Pharm Res 2012; 29:2189-201. [PMID: 22477073 PMCID: PMC3399083 DOI: 10.1007/s11095-012-0748-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 03/22/2012] [Indexed: 01/06/2023]
Abstract
Purpose To image SDS distribution across different skin regions, to compare the permeability difference between porcine and human skin, and to evaluate the interaction between SDS and skin. Methods Full thickness porcine and human skin was treated with acyl chain perdeuterated SDS (SDS-d25) at room temperature and at 34 °C for 3, 24 and 40 h. SDS distribution in skin was monitored by confocal Raman and IR microspectroscopic imaging. Permeation profiles of SDS-d25 in skin were derived from the band intensities of the CD2 stretching vibrations. The interaction between SDS and skin was monitored through the CH2 and CD2 stretching frequencies and the Amide I and II spectral region. Results SDS-d25 penetrates both porcine and human skin in a time and temperature-dependent manner, with slightly higher permeability through the stratum corneum (SC) in porcine skin. When SDS permeates into the SC, its chains are more ordered compared to SDS micelles. The secondary structure of keratin in the SC is not affected by SDS-d25. Conclusion The spatial distribution of SDS-d25 in skin was obtained for the first time. Infrared microscopic imaging provides unique opportunities to measure concentration profiles of exogenous materials in skin and offers insights to interaction between permeants and skin. Electronic supplementary material The online version of this article (doi:10.1007/s11095-012-0748-y) contains supplementary material, which is available to authorized users.
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Chiu PL, Mastrogiovanni DDT, Wei D, Louis C, Jeong M, Yu G, Saad P, Flach CR, Mendelsohn R, Garfunkel E, He H. Microwave- and nitronium ion-enabled rapid and direct production of highly conductive low-oxygen graphene. J Am Chem Soc 2012; 134:5850-6. [PMID: 22385480 DOI: 10.1021/ja210725p] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Currently the preferred method for large-scale production of solution-processable graphene is via a nonconductive graphene oxide (GO) pathway, which uncontrollably cuts sheets into small pieces and/or introduces nanometer-sized holes in the basal plane. These structural changes significantly decrease some of graphene's remarkable electrical and mechanical properties. Here, we report an unprecedented fast and scalable approach to avoid these problems and directly produce large, highly conductive graphene sheets. This approach intentionally excludes KMnO(4) from Hummers' methods and exploits aromatic oxidation by nitronium ions combined with the unique properties of microwave heating. This combination promotes rapid and simultaneous oxidation of multiple non-neighboring carbon atoms across an entire graphene sheet, thereby producing only a minimum concentration of oxygen moieties sufficient to enable the separation of graphene sheets. Thus, separated graphene sheets, which are referred to as microwave-enabled low-oxygen graphene, are thermally stable and highly conductive without requiring further reduction. Even in the absence of polymeric or surfactant stabilizers, concentrated dispersions of graphene with clean and well-separated graphene sheets can be obtained in both aqueous and organic solvents. This rapid and scalable approach produces high-quality graphene sheets of low oxygen content, enabling a broad spectrum of applications via low-cost solution processing.
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Valenzuela LM, Zhang G, Flach C, Murthy S, Mendelsohn R, Michniak-Kohn B, Kohn J. Multiscale analysis of water uptake and erosion in biodegradable polyarylates. Polym Degrad Stab 2012; 97:410-420. [PMID: 22368310 DOI: 10.1016/j.polymdegradstab.2011.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
The role of hydration in degradation and erosion of materials, especially biomaterials used in scaffolds and implants, was investigated by studying the distribution of water at length scales from 0.1 nm to 0.1 mm using Raman spectroscopy, small-angle neutron scattering (SANS), Raman confocal imaging, and scanning electron microscopy (SEM). The measurements were demonstrated using L-tyrosine derived polyarylates. Bound- and free- water were characterized using their respective signatures in the Raman spectra. In the presence of deuterium oxide (D(2)O), H-D exchange occurred at the amide carbonyl but was not detected at the ester carbonyl. Water appeared to be present in the polymer even in regions where there was little evidence for N-H to N-D exchange. SANS showed that water is not uniformly dispersed in the polymer matrix. The distribution of water can be described as mass fractals in polymers with low water content (~5 wt%), and surface fractals in polymers with larger water content (15 to 60 wt%). These fluctuations in the density of water distribution are presumed to be the precursors of the ~ 20 μm water pockets seen by Raman confocal imaging, and also give rise to 10-50 μm porous network seen in SEM. The surfaces of these polymers appeared to resist erosion while the core of the films continued to erode to form a porous structure. This could be due to differences in either the density of the polymer or the solvent environment in the bulk vs. the surface, or a combination of these two factors. There was no correlation between the rate of degradation and the amount of water uptake in these polymers, and this suggests that it is the bound-water and not the total amount of water that contributes to hydrolytic degradation.
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Saad P, Flach CR, Walters RM, Mendelsohn R. Infrared spectroscopic studies of sodium dodecyl sulphate permeation and interaction with stratum corneum lipids in skin. Int J Cosmet Sci 2011; 34:36-43. [DOI: 10.1111/j.1468-2494.2011.00678.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
BACKGROUND Bone strength depends on both bone quantity and quality. The former is routinely estimated in clinical settings through bone mineral density measurements but not the latter. Bone quality encompasses the structural and material properties of bone. Although its importance is appreciated, its contribution in determining bone strength has been difficult to precisely quantify partly because it is multifactorial and requires investigation of all bone hierarchical levels. Fourier transform infrared spectroscopy provides one way to explore these levels. QUESTIONS/PURPOSES The purposes of our review were to (1) provide a brief overview of Fourier transform infrared spectroscopy as a way to establish bone quality, (2) review the major bone material parameters determined from Fourier transform infrared spectroscopy, and (3) review the role of Fourier transform infrared microspectroscopic analysis in establishing bone quality. METHODS We used the ISI Web of Knowledge database initially to identify articles containing the Boolean term "infrared" AND "bone." We then focused on articles on infrared spectroscopy in bone-related journals. RESULTS Infrared spectroscopy provides information on bone material properties. Their microspectroscopic versions allow one to establish these properties as a function of anatomic location, mineralization extent, and bone metabolic activity. It provides answers pertaining to the contribution of mineral to matrix ratio, mineral maturity, mineral carbonate substitution, and collagen crosslinks to bone strength. Alterations of bone material properties have been identified in disease (especially osteoporosis) not attainable by other techniques. CONCLUSIONS Infrared spectroscopic analysis is a powerful tool for establishing the important material properties contributing to bone strength and thus has helped better understand changes in fragile bone.
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Zhang Q, Andrew Chan KL, Zhang G, Gillece T, Senak L, Moore DJ, Mendelsohn R, Flach CR. Raman microspectroscopic and dynamic vapor sorption characterization of hydration in collagen and dermal tissue. Biopolymers 2011; 95:607-15. [DOI: 10.1002/bip.21618] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 02/23/2011] [Accepted: 02/23/2011] [Indexed: 11/08/2022]
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Zhang Q, Chan KA, Zhang G, Gillece T, Senak L, Moore DJ, Mendelsohn R, Flach CR. Confocal Raman Spectroscopy of Collagen Hydration: from Human Type I Collagen to Dermal Tissue. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.1913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Taraschi T, Mendelsohn R. Lipid-protein interaction in the glycophorin-dipalmitoylphosphatidylcholine system: Raman spectroscopic investigation. Proc Natl Acad Sci U S A 2010; 77:2362-6. [PMID: 16592811 PMCID: PMC349397 DOI: 10.1073/pnas.77.5.2362] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Raman spectra have been recorded as a function of temperature for lipid-protein complexes of glycophorin isolated from erythrocyte membranes reconstituted with dipalmitoylphosphatidylcholine (DPPC) and its chain perdeuterated analogue ([(2)H(62)]DPPC). The conformation of the phospholipid hydrocarbon chains in the vicinity of protein is drastically altered from that in pure lipid dispersions. Analysis of the chain C-(2)H stretching vibrations for complexes of [(2)H(62)]-DPPC-glycophorin shows that at lipid:protein mole ratios of 125:1, a broad melting event occurs that is not observable by calorimetric techniques. The midpoint occurs at temperatures about 15 degrees C below that of the gel/liquid crystal phase transition for [(2)H(62)]DPPC in multilamellar dispersions. The same number of gauche rotamers form in the phospholipid hydrocarbon chains during the melting process as in the phase transition of the unperturbed molecule. Analysis of the C-H stretching region of the Raman spectrum in DPPC-glycophorin complexes indicates that lateral interactions between phospholipid chains in the complex are reduced so that interchain vibrational coupling is minimized. The observed differences between the Raman melting curves and the calorimetric endothermic transitions arise because different populations of phospholipid molecules are sampled in the two experiments. The advantages of Raman spectroscopy for the study of lipid-protein interaction are demonstrated in the current work. Implications for the structure of the lipid in the immediate vicinity of membrane protein are discussed.
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Mendelsohn R, Dluhy RA, Cameron DG, Mantsch HH. Raman and Fourier Transform Infrared Spectroscopic Studies of the Interaction between Glycophorin and Dimyristoylphosphatidylcholine. Biophys J 2010; 37:83-4. [PMID: 19431515 DOI: 10.1016/s0006-3495(82)84611-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Seaton BA, Crouch EC, McCormack FX, Head JF, Hartshorn KL, Mendelsohn R. Review: Structural determinants of pattern recognition by lung collectins. Innate Immun 2010; 16:143-50. [PMID: 20423923 DOI: 10.1177/1753425910368716] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Host defense roles for the lung collectins, surfactant protein A (SP-A) and surfactant protein D (SP-D), were first suspected in the 1980s when molecular characterization revealed their sequence homology to the acute phase reactant of serum, mannose-binding lectin. Surfactant protein A and SP-D have since been shown to play diverse and important roles in innate immunity and pulmonary homeostasis. Their location in surfactant ideally positions them to interact with air-space pathogens. Despite extensive structural similarity, the two proteins show many functional differences and considerable divergence in their interactions with microbial surface components, surfactant lipids, and other ligands. Recent crystallographic studies have provided many new insights relating to these observed differences. Although both proteins can participate in calcium-dependent interactions with sugars and other polyols, they display significant differences in the spatial orientation, charge, and hydrophobicity of their binding surfaces. Surfactant protein D appears particularly adapted to interactions with complex carbohydrates and anionic phospholipids, such as phosphatidylinositol. By contrast, SP-A shows features consistent with its preference for lipid ligands, including lipid A and the major surfactant lipid, dipalmitoylphosphatidylcholine. Current research suggests that structural biology approaches will help to elucidate the molecular basis of pulmonary collectin-ligand recognition and facilitate development of new therapeutics based upon SP-A and SP-D.
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Mostafavi D, Zhang G, Mendelsohn R, Chu DS. Descemet's Membrane Detachment Caused by the Improper Injection of Sodium Hyaluronate. Ophthalmic Surg Lasers Imaging Retina 2010; 41:1-3. [PMID: 20337303 DOI: 10.3928/15428877-20100215-69] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2009] [Indexed: 05/29/2023]
Abstract
A case of a Descemet's membrane detachment (DMD) caused by the inadvertent intracorneal injection of sodium hyaluronate was presented. This was concluded after chemical analysis of a viscous substance found in a patient's cornea showed to be a breakdown product of sodium hyaluronate. Surgical correction of the detachment included removing the viscous substance and tamponading the detachment with an air bubble. Although other gases such as sulfur hexafluoride (SF6) provide longer means of tamponade, they have increased postoperative risks like glaucoma associated with their use. Air can provide an effective means of tamponade with minimal postoperative risks.
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Mendelsohn R, Mao G, Flach CR. Infrared reflection-absorption spectroscopy: principles and applications to lipid-protein interaction in Langmuir films. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:788-800. [PMID: 20004639 DOI: 10.1016/j.bbamem.2009.11.024] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 11/19/2009] [Accepted: 11/24/2009] [Indexed: 01/08/2023]
Abstract
Infrared reflection-absorption spectroscopy (IRRAS) of lipid/protein monolayer films in situ at the air/water interface provides unique molecular structure and orientation information from the film constituents. The technique is thus well suited for studies of lipid/protein interaction in a physiologically relevant environment. Initially, the nature of the IRRAS experiment is described and the molecular structure information that may be obtained is recapitulated. Subsequently, several types of applications, including the determination of lipid chain conformation and tilt as well as elucidation of protein secondary structure are reviewed. The current article attempts to provide the reader with an understanding of the current capabilities of IRRAS instrumentation and the type of results that have been achieved to date from IRRAS studies of lipids, proteins, and lipid/protein films of progressively increasing complexity. Finally, possible extensions of the technology are briefly considered.
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Saad P, Moore D, Moore DJ, Flach E, Flach CR, Mendelsohn R. Quantitative IR Spectroscopy Studies of Changes in Lipid Dynamics and Organization in Isolated Stratum Corneum Exposed to Basic pH. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.1501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Gourion-Arsiquaud S, Burket JC, Havill LM, DiCarlo E, Doty SB, Mendelsohn R, van der Meulen MCH, Boskey AL. Spatial variation in osteonal bone properties relative to tissue and animal age. J Bone Miner Res 2009; 24:1271-81. [PMID: 19210217 PMCID: PMC2697626 DOI: 10.1359/jbmr.090201] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 01/02/2009] [Accepted: 02/02/2009] [Indexed: 11/18/2022]
Abstract
Little is known about osteonal bone mineral and matrix properties, although these properties are of major importance for the understanding of bone alterations related to age and bone diseases such as osteoporosis. During aging, bone undergoes modifications that compromise their structural integrity as shown clinically by the increase of fracture incidence with age. Based on Fourier transform infrared (FTIR) analysis from baboons between 0 and 32 yr of age, consistent systematic variations in bone properties as a function of tissue age are reported within osteons. The patterns observed were independent of animal age and positively correlated with bone tissue elastic behavior measured by nano-indentation. As long as tissue age is expressed as a percentage of the entire osteon radius, osteonal analyses can be used to characterize disease changes independent of the size of the osteon. These mineral and matrix analyses can be used to explain bone fragility. The mineral content (mineral-to-matrix ratio) was correlated with the animal age in both old (interstitial) and newly formed bone tissue, showing for the first time that age-related changes in BMC can be explain by an alteration in the mineralization process itself and not only by an imbalance in the remodeling process.
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Andrew Chan KL, Zhang G, Tomic-Canic M, Stojadinovic O, Lee B, Flach CR, Mendelsohn R. A coordinated approach to cutaneous wound healing: vibrational microscopy and molecular biology. J Cell Mol Med 2009; 12:2145-54. [PMID: 19145704 PMCID: PMC4506178 DOI: 10.1111/j.1582-4934.2008.00459.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The repair of cutaneous wounds in the adult body involves a complex series of spatially and temporally organized processes to prevent infection and restore homeostasis. Three characteristic phases of wound repair (inflammation, proliferation including re-epithelialization and remodelling) overlap in time and space. We have utilized a human skin wound-healing model to correlate changes in genotype and pheno-type with infrared (IR) and confocal Raman spectroscopic images during the re-epithelialization of excisional wounds. The experimental protocols validated as IR images clearly delineate the keratin-rich migrating epithelial tongue from the collagen-rich wound bed. Multivariate statistical analysis of IR datasets acquired 6 days post-wounding reveal subtle spectral differences that map to distinct spatial distributions, which are correlated with immunofluorescent staining patterns of different keratin types. Images computed within collagen-rich regions expose complementary spatial patterns and identify elastin in the wound bed. The temporal sequence of events is explored through a comparison of gene array analysis with confocal Raman microscopy. Our approach demonstrates the feasibility of acquiring detailed molecular structure information from the various proteins and their subclasses involved in the wound-healing process.
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Taratula O, Galoppini E, Mendelsohn R, Reyes PI, Zhang Z, Duan Z, Zhong J, Lu Y. Stepwise functionalization of ZnO nanotips with DNA. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:2107-2113. [PMID: 19199718 DOI: 10.1021/la8026946] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A surface functionalization methodology for the development of ZnO nanotips biosensors that can be integrated with microelectronics was developed. Two types of long chain carboxylic acids linkers were employed for the functionalization of 0.5 mum thick MOCVD-grown ZnO nanotip films with single-stranded DNA (ssDNA), followed by hybridization with complementary ssDNA tagged with fluorescein. The ZnO functionalization strategy was developed for the fabrication of ZnO nanotips-linker-biomolecule films integrated with bulk acoustic wave (BAW) biosensors, and it involved three main steps. First, 16-(2-pyridyldithiol)hexadecanoic acid or N-(15-carboxypentadecanoyloxy)succinimide, both bifunctional C16 carboxylic acids, were bound to ZnO nanotip films through the COOH group, leaving at the opposite end of the alkyl chain a thiol group protected as a 2-pyridyl disulfide, or a carboxylic group protected as a N-succinimide, respectively. In the second step, ssDNA was covalently linked to each type of ZnO-linker film: the 2-pyridyl disulfide end group was substituted with 16 bases 5'-thiol-modified DNA (SH-ssDNA), and the N-succinimide ester end group was substituted with 16 bases 5'-amino-modified DNA (NH(2)-ssDNA). In the third step, the DNA-functionalized ZnO nanotip films were hybridized with complementary 5'-fluorescein ssDNA. The surface-modified ZnO nanotip films were characterized after each step by FT-IR-ATR, fluorescence emission spectroscopy, and fluorescence microscopy. This functionalization approach allows sequential reactions on the surface and, in principle, can be extended to numerous other molecules and biomolecules.
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Mao G, Wang L, Brauner JW, McCormack FX, Crouch E, Seaton B, Head J, Smith K, Flach CR, Mendelsohn R. IRRAS Studies of the Host Defense Effect of Pulmonary Surfactants SP-A and SP-D. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.3115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Wang L, Brauner JW, Mao G, Crouch E, Seaton B, Head J, Smith K, Flach CR, Mendelsohn R. Interaction of recombinant surfactant protein D with lipopolysaccharide: conformation and orientation of bound protein by IRRAS and simulations. Biochemistry 2008; 47:8103-13. [PMID: 18620419 DOI: 10.1021/bi800626h] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Effective innate host defense requires early recognition of pathogens. Surfactant protein D (SP-D), shown to play a role in host defense, binds to the lipopolysaccharide (LPS) component of Gram-negative bacterial membranes. Binding takes place via the carbohydrate recognition domain (CRD) of SP-D. Recombinant trimeric neck+CRDs (NCRD) have proven valuable in biophysical studies of specific interactions. Although X-ray crystallography has provided atomic level information on NCRD binding to carbohydrates and other ligands, molecular level information about interactions between SP-D and biological ligands under physiologically relevant conditions is lacking. Infrared reflection-absorption spectroscopy (IRRAS) provides molecular structure information from films at the air/water interface where protein adsorption to LPS monolayers serves as a model for protein-lipid interaction. In the current studies, we examine the adsorption of NCRDs to Rd 1 LPS monolayers using surface pressure measurements and IRRAS. Measurements of surface pressure, Amide I band intensities, and LPS acyl chain conformational ordering, along with the introduction of EDTA, permit discrimination of Ca (2+)-mediated binding from nonspecific protein adsorption. The findings support the concept of specific binding between the CRD and heptoses in the core region of LPS. In addition, a novel simulation method that accurately predicts the IR Amide I contour from X-ray coordinates of NCRD SP-D is applied and coupled to quantitative IRRAS equations providing information on protein orientation. Marked differences in orientation are found when the NCRD binds to LPS compared to nonspecific adsorption. The geometry suggests that all three CRDs are simultaneously bound to LPS under conditions that support the Ca (2+)-mediated interaction.
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