Physiological Media Research Articles

The Characterization of Titanium Particles Released from Bone-Level Titanium Dental Implants: Effect of the Size of Particles on the Ion Release and Cytotoxicity Behaviour

Many studies are being carried out on the particles released during the implantoplasty process in the machining of dental implants to remove bacterial biofilms. However, there are no studies on the release of particles produced by the insertion of bone-level dental implants due to the high compressive frictional loads between the rough titanium implant and the bone tissue. This paper aims to characterize the released particles and determine the release of titanium ions into the physiological environment and their cytocompatibility. For this purpose, 90 dental implants with a neck diameter of 4 mm and a torque of 22 Ncm were placed in 7 fresh cow ribs. The placement was carried out according to the established protocols. The implants had a roughness Ra of 1.92 μm. The arrangement of the particles in the bone tissue was studied by micro-CT, and no particle clusters were observed. The different granulometries of 5, 15, and 30 μm were obtained; the specific surface area was determined by laser diffraction; the topography was determined by scanning electron microcopy; and the particles were chemically analysed by X-ray energy microanalysis. The residual stresses of the particles were obtained by X-ray diffraction using the Bragg-Bentano configuration. The release of titanium ions to the physiological medium was performed using ICP-MS at 1, 3, 7, 14, and 21 days. The cytocompatibility of the particles with HFF-1 fibroblast and SAOS-2 osteoblast cultures was characterized. The results showed that the lowest specific surface area (0.2109 m2/g) corresponds to the particles larger than 30 μm being higher than 0.4969 and 0.4802 m2/g of those that are 5 and 15 μm, respectively, observing in all cases that the particles have irregular morphologies without contamination of the drills used in the surgery. The highest residual stresses were found for the small particles, −395 MPa for the 5 μm particles, and −369 for the 15 μm particles, and the lowest residual stresses were found for the 30 μm particles with values of −267 MPa. In all cases, the residual stresses were compressive. The lowest ion release was for the 30 μm samples, as they have the lowest specific surface area. Cytocompatibility studies showed that the particles are cytocompatible, but it is the smallest ones that are lower and very close to the 70% survival limit in both fibroblasts and osteoblasts.

Novel NIR-Phosphorescent Ir(III) Complexes: Synthesis, Characterization and Their Exploration as Lifetime-Based O2 Sensors in Living Cells.

A series of [Ir(N^C)2(N^N)]+ NIR-emitting orthometalated complexes (1–7) has been prepared and structurally characterized using elemental analysis, mass-spectrometry, and NMR spectroscopy. The complexes display intense phosphorescence with vibrationally structured emission bands exhibiting the maxima in the range 713–722 nm. The DFT and TD DFT calculations showed that the photophysical characteristics of these complexes are largely determined by the properties of the metalating N^C ligands, with their major contribution into formation of the lowest S1 and T1 excited states responsible for low energy absorption and emission, respectively. Emission lifetimes of 1–7 in degassed methanol solution vary from 1.76 to 5.39 µs and show strong quenching with molecular oxygen to provide an order of magnitude lifetime reduction in aerated solution. The photophysics of two complexes (1 and 7) were studied in model physiological media containing fetal bovine serum (FBS) and Dulbecco’s Modified Eagle Medium (DMEM) to give linear Stern-Volmer calibrations with substantially lower oxygen-quenching constants compared to those obtained in methanol solution. These observations were interpreted in terms of the sensors’ interaction with albumin, which is an abundant component of FBS and cell media. The studied complexes displayed acceptable cytotoxicity and preferential localization, either in mitochondria (1) or in lysosomes (7) of the CHO-K1 cell line. The results of the phosphorescence lifetime imaging (PLIM) experiments demonstrated considerable variations of the sensors’ lifetimes under normoxia and hypoxia conditions and indicated their applicability for semi-quantitative measurements of oxygen concentration in living cells. The complexes’ emission in the NIR domain and the excitation spectrum, extending down to ca. 600 nm, also showed that they are promising for use in in vivo studies.

Encapsulation of Hydrophobic Porphyrins into Biocompatible Nanoparticles: An Easy Way to Benefit of Their Two-Photon Phototherapeutic Effect without Hydrophilic Functionalization.

Simple SummaryEfficient photosensitizers for photodyanmic therapy (PDT) need to be soluble in physiologic media. This requirement often complicates significantly the chemical access to such compounds, resulting in lower availability and higher production costs for the best representatives. Given that their screening and selection is often initially conducted in organic media from series of hydrophobic model compounds, the possibility to use directly such hydrophobic photosensitizers in real PDT studies was highly desirable to speed up their definitive identification but also to alleviate their cost. In this respect, PMLABe polymeric nanoparticles (NPs) were presently probed as nanocarriers to water-solubilize hydophobic star-shaped porphyrin-based which turned out to be promising oxygen photosensitizers for theranostic approaches. We show here that PDT conducted using such NPs loaded with these compounds is as efficient than when functional hydrosoluble analogues of these photosensitiers are tested alone and that tracking of the photosensitizer by fluorescence imaging is even easier.Star-shaped hydrophobic porphyrins, acting as powerful fluorescent two-photon photosensitizers for oxygen in organic solvents, can easily be loaded into PMLABe polymeric nanoparticles at various concentrations. In this contribution, the performance of these porphyrin-containing nanoparticles in terms of photodynamic therapy (PDT) is compared to those of the corresponding water-soluble porphyrin analogues when irradiated in MCF-7 cancer cells. While quite promising results are obtained for performing PDT with these nanoparticles, validating this approach as a mean for using more easily accessible and less expensive photosensitizers, from a synthetic perspective, we also show that their luminescence can still be used for bioimaging purposes in spite of their confinement in the nanoparticles, validating also the use of these nano-objects for theranostic purposes.

Investigating the Conditionally Essential Role of Human METAP1

CRISPR‐based forward genetic screens make it possible to systematically identify genes required for survival and growth in human cells, and therefore provide a powerful approach to characterize protein function and uncover targetable vulnerabilities in human cancer cells. Notably, it has become appreciated that gene essentiality can be context‐dependent, as CRISPR‐based loss‐of‐function screens across hundreds of human cancer cell lines have uncovered cell‐essential genes that can vary with cell‐intrinsic characteristics such as genotype and lineage. Importantly, environmental factors also influence cell physiology. However, there has been little consideration into how nutrient availability might impact gene essentiality, and most CRISPR‐based screens of human cells are performed in vitro using culture media that poorly recapitulate nutrient conditions in the body. To test the hypothesis that medium composition influences gene essentiality, our lab recently performed genome‐wide CRISPR screens of human blood cancer cell lines in traditional versus Human Plasma‐Like Medium (HPLM), a physiologic medium that we previously developed to more closely reflect the metabolic composition of human blood. Among the strongest HPLM‐essential hits identified from our screen results is METAP1, which encodes one of two human enzymes (METAP1 and METAP2) that can catalyze the cleavage of N‐terminal methionine from nascent polypeptides. Interestingly, these two METAPs are co‐expressed across most human cell lines, are each localized to the cytosol, and also share seemingly similar substrate preferences. However, our screen results indicate that endogenous METAP2 cannot complement the loss of METAP1in HPLM‐cultured cells, suggesting that METAP1 serves a non‐redundant and context‐dependent cell‐essential role. Therefore, we hypothesize that identifying the gene‐nutrient interaction that underlies conditional METAP1essentiality will provide key insights into this unforeseen role. Importantly, we have engineered METAP1‐knockout cells and, in turn, confirmed the conditional CRISPR phenotype for METAP1by performing relative growth assays. Therefore, we are now poised to identify the gene‐nutrient interaction and will proceed to use tools in biochemistry, metabolomics, and molecular biology to explore the context‐dependent role of METAP1 in proliferating human cells.

Physiological Media in Studies of Cell Metabolism

Changes in cell metabolism accompany the development of a wide spectrum of pathologies including cancer, autoimmune, and inflammatory diseases. Therefore, usage of inhibitors of metabolic enzymes are considered a promising strategy for the development of therapeutic agents. However, the investigation of cellular metabolism is hampered by the significant impact of culture media, which interfere with many cellular processes, thus making cellular models irrelevant. There are numerous reports that show that the results from in vitro systems are not reproduced in in vivo models and patients. Over the last decade a novel approach has emerged, which consists of adaptation of the culture medium composition to that closer to the composition of blood plasma. In 2017-2019, two plasma-like media were proposed, Plasmax and HPLM. In the review, we have summarized the drawbacks of common media and have analyzed changes in the metabolism of cells cultivated in common and plasma-like media in normal and pathological conditions.

Uncovering the Conditionally Essential Roles of NAD Kinases in Human Cells

Forward genetic screens across hundreds of human cancer cell lines have been used to identify genetic dependencies of proliferating human cells and how these vary by genotype and cell lineage. However, while it is appreciated that environmental factors influence cell physiology, there has been little investigation into how nutrient availability impacts gene essentiality. Further, most such screens have been performed in vitro using culture media that poorly reflect the metabolic composition of human blood. Previously, we developed Human Plasma‐Like Medium (HPLM), a physiologic medium designed to more closely reflect the biochemical conditions in human blood. To determine how medium composition affects gene essentiality, we recently performed CRISPR‐based screens of K562 leukemia cells in HPLM versus RPMI, the medium historically used to culture human blood cells. Among the strongest scoring HPLM‐essential genes is Nicotinamide Adenine Dinucleotide Kinase (NADK), which encodes one of two human NAD kinases (NADK, cytosolic; NADK2, mitochondrial) that can catalyze the phosphorylation of NAD(H)to NADP(H). While most human cells co‐express both isozymes, only NADK was identified as HPLM‐essential, suggesting that endogenous NADK2 expression is not sufficient to complement NADK knockout in HPLM‐cultured cells. Interestingly, NADK has been annotated as an essential gene in less than 1% of over 1000 genome‐wide CRISPR‐based screens from the Broad Institute Cancer Dependency Map project. To begin to investigate the conditional CRISPR phenotype for NADK, we first engineered NADK‐knockout cells and then found that they showed a 40% growth defect versus control cells in HPLM relative to RPMI using a short‐term growth assay. Next, to test the hypothesis that cytosolic NAD kinase activity is required for the conditionally essential role of NADK, we performed similar short‐term growth assays with NADK‐knockout cells expressing cDNAs for wild‐type and cytosol‐restricted NADK2, as well as kinase‐dead NADK. These experiments revealed that neither kinase‐dead NADK nor NADK2 overexpression could rescue the growth defect of NADK‐knockout cells, but that cytosol‐restricted NADK2 could. Collectively, these results indicate that the conditionally essential role of NADK is linked to its cytosolic NAD kinase activity. Currently, we are applying systematic approaches in media engineering and metabolomics to identify the medium component(s) that contribute to the NADK gene‐nutrient interaction, and to gain insights into the non‐redundant, context‐dependent role of NADK. Lastly, through further conditional essentiality profiling, we identified NADK2as DMEM‐essential versus HPLM. Consistent with two recently published studies, we traced this effect to the differential availability of proline between HPLM and DMEM. Collectively, our results demonstrate the human NADKs fulfill distinct cell‐essential roles and form distinct gene‐nutrient interactions that vary with their subcellular localization.

Uncovering conditional vulnerabilities in human cancer cells

Forward genetic screens based on either RNAi or CRISPR make it possible to systematically identify genes required for the survival and growth of mammalian cells, and thus offer a powerful approach to characterize protein function and identify potential cancer vulnerabilities. Nonetheless, fitness genes can be context‐dependent, and indeed, CRISPR screens across hundreds of human cell lines have revealed that genetic dependencies can vary with natural cell‐intrinsic diversity. However, while the impact of environmental factors on cell physiology has become better appreciated, there has been little investigation into how nutrient availability affects gene essentiality and, further, most forward genetic screens are performed in vitro using culture media with little relevance to human physiology. We previously developed Human Plasma‐Like Medium (HPLM) – the first systematically designed physiologic medium, which contains over 60 components at concentrations that reflect their average values in human blood. To test the hypothesis that medium composition influences gene essentiality, we performed CRISPR‐based loss‐of‐function screens of blood cancer lines HPLM versus traditional media. Analysis of these data revealed that sets of conditionally essential genes are involved in several biological processes and can vary with both cell‐intrinsic diversity and the combination of basal and serum components that comprise typical media. Moreover, our approach allows for the downstream identification of gene‐nutrient interactions that underlie conditional CRISPR phenotypes, which can in turn uncover conditionally essential protein roles.Additionally, most preclinical therapies fail to achieve translation – a major problem attributed in part to the limited physiologic relevance of existing models. Nonetheless, there has been similarly little systematic investigation into how the composition of culture media might affect drug efficacy. Further, virtually all drug screens, initial hit validation efforts, and studies of drug activity are performed in vitro using traditional media as well. Therefore, we with collaborators at NCATS used a library of approved and (pre)‐clinical drugs to screen blood cancer lines in HPLM versus conventional media. Remarkably, we identified many whose killing activity varied with medium composition, including drugs approved for non‐oncology indications. Indeed, neither the drug‐nutrient interaction nor the mechanism of drug activity in cancer cells is immediately apparent in many such cases.

Lithocholic acid conjugated mPEG-b-PCL micelles for pH responsive delivery to breast cancer cells

In this study, micelles composed of methoxy poly(ethylene glycol)-block-poly(ε-caprolactone) copolymer (mPEG-b-PCL), which has ionically conjugated lithocholic acid (LCA) and providing pH sensitive release of LCA in acidic media, were prepared as drug carrier devices for cancer therapy. Micelles were produced by co-solvent evaporation method at two different temperatures (60 °C and 25 °C) and coded as LCA60**M and LCA25**M, respectively). Hydrodynamic diameters were 86.9 nm and 228.2 nm, and zeta potentials were −7.54 mV and −18.83 mV for LCA60**M and LCA25**M, respectively. For all micelles, release of LCA was higher in acidic media (pH 5.0) compared to physiological media (pH 7.4). Micelles loaded with a fluorescent dye, coumarin 6, demonstrated effective internalization into triple negative MDA-MB-231 breast cancer cells in 4 h. LCA60**M (41.7 ± 1.5%) and LCA25**M (44.5 ± 2.2%) had higher inhibitory effect on the cell migration compared to free LCA (64.7 ± 1.3%). Both LCA conjugated micelles decreased lipogenic activity and increased expressions of Bax (1.3 fold) and p53 (1.2 fold) apoptotic genes. Annexin V-FITC results exhibited high apoptotic cell number after the treatment of MDA-MB-231 cells with micelles. Free LCA and LCA conjugated LCA60**M and LCA25**M micelles decreased mitochondrial transmembrane potential of the cells by 41.8 ± 3.0%, 30.4 ± 0.9%, and 57.1 ± 0.5, respectively. Micelles also caused an effective decrease in angiogenesis ability of HUVECs. The novelty of this study is the prepared micelles, which have ionic conjugation of LCA to mPEG-b-PCL, and pH responsive release of LCA demonstrating effective apoptosis on breast cancer cells. These micelles may have great potential for cancer treatment. However, further in vivo studies are needed before clinical translation.

Cephalexin loading and controlled release studies on mesoporous silica functionalized with amino groups

KIT-6 mesoporous silica has been synthesized using the sol-gel method and functionalized with 3-aminopropyl triethoxysilane by grafting route to obtain KIT-6/NH2. These samples were used as carriers in the loading and controlled release of cephalexin (CFX). The effect of temperature and gastric and intestinal pH on the stability of pure CFX and loaded in KIT-6 and KIT-6/NH2 were investigated. The properties of the synthesized materials and their CFX loading capacity were studied through FTIR, ads-des N2 at 77 K, TEM, SEM, XPS, and TGA. The controlled release tests were carried out in a simulated physiological medium at gastric (1.2) and intestinal pH (6.8). Furthermore, the biocompatibility of both materials was studied through cell viability tests in Caco-2 intestinal cells. The results revealed that KIT-6 and KIT-6/NH2 had similar CFX loading capacities. It was found that CFX degrades at pH 6.8, however, KIT-6 and KIT-6/NH2 were able to protect it from the aforementioned degradation. Moreover, KIT-6 materials presented a good performance as CFX carriers since both materials provided diffusion-controlled release profiles during 24 h, satisfying the Korsmeyer-Peppas kinetic model. Mesoporous silicas presented in this work are promising candidates to be used in CFX controlled release systems due to their chemical interactions, textural properties, and high cell viability.

Bipolar versus monopolar transurethral resection for benign prostatic hypertrophy: a prospective comparative study

Background: The transurethral resection of the prostate (TURP) is a well-known surgical procedure for treating benign prostatic hypertrophy in males. Monopolar TURP (MTURP) has been used in the past, however the morbidity associated with MTURP has led to the development of new surgical procedures. Energy is restricted between electrodes at the resectoscope site in bipolar TURP (BTURP), permitting the use of physiological irrigation medium. In terms of patient outcomes, there is still some doubt about the distinctions between various surgical procedures. This study aims to evaluate the efficacy of monopolar (M-TURP) and bipolar (B-TURP) TURP.Methods: In this prospective comparison trial, 100 patients were enrolled and table randomized to either M-TURP or B-TURP surgery for prostatic hyperplasia. Prostate size, post-void volume and hemoglobin were recorded pre and postoperatively. Resection time was noted.Results: Patients were divided into two groups, namely M-TURP and B-TURP. The mean age of patients was comparable between both groups. There is a significantly lower mean resection time in M-TURP compared to B-TURP. Drop-in hemoglobin levels (g/dl) in M-TURP patients were higher than in B-TURP. The M-TURP group showed a higher reduction in post-void residual volume than the B-TURP group. B-TURP group had a larger reduction in gland size than the M-TURP group.Conclusions: M-TURP and B-TURP are safe and effective procedures for treating BPH.

On‐chip microfluidic buffer swap of biological samples in‐line with downstream dielectrophoresis

Microfluidic cell enrichment by dielectrophoresis, based on biophysical and electrophysiology phenotypes, requires that cells be resuspended from their physiological media into a lower conductivity buffer for enhancing force fields and enabling the dielectric contrast needed for separation. To ensure that sensitive cells are not subject to centrifugation for resuspension and spend minimal time outside of their culture media, we present an on‐chip microfluidic strategy for swapping cells into media tailored for dielectrophoresis. This strategy transfers cells from physiological media into a 100‐fold lower conductivity media by using tangential flows of low media conductivity at 200‐fold higher flow rate versus sample flow to promote ion diffusion over the length of a straight channel architecture that maintains laminarity of the flow‐focused sample and minimizes cell dispersion across streamlines. Serpentine channels are used downstream from the flow‐focusing region to modulate hydrodynamic resistance of the central sample outlet versus flanking outlets that remove excess buffer, so that cell streamlines are collected in the exchanged buffer with minimal dilution in cell numbers and at flow rates that support dielectrophoresis. We envision integration of this on‐chip sample preparation platform prior to or post‐dielectrophoresis, in‐line with on‐chip monitoring of the outlet sample for metrics of media conductivity, cell velocity, cell viability, cell position, and collected cell numbers, so that the cell flow rate and streamlines can be tailored for enabling dielectrophoretic separations from heterogeneous samples.

Hydrophilic bis-MPA hyperbranched dendritic scaffolds as nanocarriers of a fully characterized flavonoid morin-Zn(II) complex for anticancer applications

In this work the first crystallographically characterized complex of the bioactive flavonoid morin with the Zn(II) ion is presented along with its complete physico-chemical characterization. In view of the antioxidant activity of morin and its toxicity against respiratory tract cancers, the encapsulation of the complex in the hydrophilic bis(methylol)propionic acid hyperbranched dendritic scaffolds (bis-MPA HDSs) was effected. The produced nano-formulations were characterized with physico-chemical and electron microscopy techniques, and biologically evaluated for their antioxidant and anticancer activity against human A549 and H520 lung cancer cells, as well as healthy human MRC-5 lung fibroblasts. The obtained results demonstrate that encapsulation increases the solubility, and thus bioavailability, of the complex in physiological media and enhances anticancer action. They also highlight the importance of the non-toxic bis-MPA HDSs as nanocarriers of bioactive flavonoid metal complexes for anticancer therapeutic applications.

Unveiling the reaction mechanism of co-reactant electrochemiluminescence behavior of alloxan molecule using tris(2,2′-bipyridine)ruthenium(II) as a luminophore and its potential of sensing application

Alloxan is a cytotoxic organic molecule that selectively damages islet β-cell in the pancreas and disrupts the production of insulin, causing alloxan-induced diabetes. Herein, for the first time, we explored alloxan molecule as a new co-reactant species for the standard ECL luminophore [Ru(bpy)3]2+in both physiological and alkaline pH medium. The simultaneous CV and ECL studies confirm that the reversible redox peak of [Ru(bpy)3]2+ becomes in irreversible nature at + 1.15 V (vs. Ag/AgCl) and its corresponding ECL peak also consistently increases with each addition of alloxan molecule. The CV, UV-Visible, Raman, NMR and HPLC results confirm that at pH 7.4 and above, the alloxan molecule is chemically transformed into alloxanic acid. The electron spin resonance (ESR) spectra further endorse that the oxidation peak at + 1.0 V is due to oxidation of alloxanic acid into alloxanic radical, which ultimately serves as anodic co-reactant for [Ru(bpy)3]2+. The proposed new ECL oxidative-reduction mechanism via energetic electron transfer takes place between alloxanic radical and the electro-oxidized [Ru(bpy)3]3+. The developed an ECL based sensor which shows more sensitive and selective detection of alloxan with a linear ranges of 100 nM - 2 mM at pH 7.4 and 10 nM - 2 mM at pH 11 with a limit of detection (LOD) value of 0.97 nM & 0.70 nM (S/N = 3) respectively. Moreover, the developed ECL based sensor is successfully applied to the sensing of alloxan in the real samples that proves the viability of the adopted ECL sensor methodology is suitable for detecting the alloxan molecule in food as well as clinical samples.

Wettability, Corrosion Resistance, and Osteoblast Response to Reduced Graphene Oxide on CoCr Functionalized with Hyaluronic Acid

The durability of metal–metal prostheses depends on achieving a higher degree of lubrication. The beneficial effect of hyaluronic acid (HA) on the friction and wear of both natural and artificial joints has been reported. For this purpose, graphene oxide layers have been electrochemically reduced on CoCr surfaces (CoCrErGO) and subsequently functionalized with HA (CoCrErGOHA). These layers have been evaluated from the point of view of wettability and corrosion resistance in a physiological medium containing HA. The wettability was analyzed by contact angle measurements in phosphate buffer saline-hyaluronic acid (PBS-HA) solution. The corrosion behavior of functionalized CoCr surfaces was studied with electrochemical measurements. Biocompatibility, cytotoxicity, and expression of proteins related to wound healing and repair were studied in osteoblast-like MC3T3-E1 cell cultures. All of the reported results suggest that HA-functionalized CoCr surfaces, through ErGO layers in HA-containing media, exhibit higher hydrophilicity and better corrosion resistance. Related to this increase in wettability was the increase in the expressions of vimentin and ICAM-1, which favored the growth and adhesion of osteoblasts. Therefore, it is a promising material for consideration in trauma applications, with improved properties in terms of wettability for promoting the adhesion and growth of osteoblasts, which is desirable in implanted materials used for bone repair.

Liposome-Tethered Gold Nanoparticles Triggered by Pulsed NIR Light for Rapid Liposome Contents Release and Endosome Escape.

Remote triggering of contents release with micron spatial and sub-second temporal resolution has been a long-time goal of medical and technical applications of liposomes. Liposomes can sequester a variety of bioactive water-soluble ions, ligands and enzymes, and oligonucleotides. The bilayer that separates the liposome interior from the exterior solution provides a physical barrier to contents release and degradation. Tethering plasmon-resonant, hollow gold nanoshells to the liposomes, or growing gold nanoparticles directly on the liposome exterior, allows liposome contents to be released by nanosecond or shorter pulses of near-infrared light (NIR). Gold nanoshells or nanoparticles strongly adsorb NIR light; cells, tissues, and physiological media are transparent to NIR, allowing penetration depths of millimeters to centimeters. Nano to picosecond pulses of NIR light rapidly heat the gold nanoshells, inducing the formation of vapor nanobubbles, similar to cavitation bubbles. The collapse of the nanobubbles generates mechanical forces that rupture bilayer membranes to rapidly release liposome contents at the preferred location and time. Here, we review the syntheses, characterization, and applications of liposomes coupled to plasmon-resonant gold nanostructures for delivering a variety of biologically important contents in vitro and in vivo with sub-micron spatial control and sub-second temporal control.

Immobilization of Concanavalin A on iron oxide magnetic nanoparticles. Effect of Bovine Serum Albumin in the recognition interactions of the lectin

Iron oxide magnetic nanoparticles are engaging platforms for diverse nanobiotechnological applications, such as proteins separation and glico-biosensing mediated by the surface functionalization with lectins as recognition elements. We present a new strategy for the union of the lectin Concanavalin A (ConA) at the surface of carboxylated iron oxide magnetic nanoparticles (IOMNPs-Ar-COOH). The nanoparticles were obtained by a single step synthesis in the presence of the aryl diazonium salt derived from 4-aminobenzoic acid. The spontaneous grafting allowed to obtain carboxylic acid covalently functionalized magnetite nanoparticles with the carboxylate group exposed to the solution, as was evidenced through the exhaustive characterization by XRD, FTIR, Raman spectroscopy, and TEM analysis. The nanoparticles of Fe3O4 of (6.6 ± 0.7) nm diameter exhibited good magnetic field responsiveness towards an external magnet and stability towards the environmental oxidation. The carboxylic acid groups exposed were used for the conjugation with ConA and participated in its adsorption onto the surface. The ability of ConA to recognize the glycoprotein Glucose Oxidase (GOx) was analyzed in real time by surface plasmon resonance. These results were correlated with the responses obtained by electrochemical methods (electrochemical impedance spectroscopy, and cyclic voltammetry). Considering the possible applications of this nanomaterial, we also evaluate the effect of Bovine Serum Albumin (BSA) in the recognition capability of ConA. Our work let us to conclude that although ConA does not specifically recognize BSA, this protein alters the affinity of ConA for GOx giving an interesting vision of the behaviour of this hybrid nanomaterial in physiological mediums or other matrixes with high concentration of proteins where this nanomaterial could be employed e.g., in a biosensor or the separation of a glycoprotein, among others.

Self-Photopolymerizable Hydrogel-Ceramic Composites with Scavenger Properties.

The photocatalytic behaviours of semiconductive ceramic nanoparticles such as TiO2, ZnO, Fe2O3, and Fe3O4, have been extensively studied in photocatalysis and photopolymerization, due to their ability to produce radical species under ultraviolet–visible light, and even in dark conditions. In addition, in the form of microparticles, TiO2 and its Magnéli phases are capable of neutralizing radical species, and a heterogeneous catalytic process has been suggested to explain this property, as it is well known as scavenging activity. Thus, in this study, we demonstrate that these ceramic powders, in the form of microparticles, could be used as photoinitiators in UV polymerization in order to synthesize a hydrogel matrix. Them, embedded ceramic powders could be able to neutralize radical species of physiological media once implanted. The hydrogel matrix would regulate the exchange of free radicals in any media, while the ceramic particles would neutralize the reactive species. Therefore, in this work, the scavenger activities of TiO2, ZnO, Fe2O3, and Fe3O4 microparticles, along with their photoinitiation yield, were evaluated. After photopolymerization, the gel fraction and swelling behaviour were evaluated for each hydrogel produced with different ceramic initiators. Gel fractions were higher than 60%, exhibiting variation in their scavenging activity. Therefore, we demonstrate that ceramic photoinitiators of TiO2, ZnO, Fe2O3, and Fe3O4 can be used to fabricate implantable devices with scavenger properties in order to neutralize radical species involved in inflammatory processes and degenerative diseases.

Red-emitting heteroleptic iridium(III) complexes: photophysical and cell labeling study.

Two red-emitting heteroleptic iridium(III) complexes (Ir-p and Ir-q) were synthesized and their photophysical and biological properties were analyzed. After their structures have been confirmed by several techniques, such as 1H NMR, 13C NMR, FT-IR, UV-Vis, and MALDI TOF analyses, their luminescence behavior was investigated in ethanol and PBS (physiological medium, pH ~ 7.4) solutions. Emission spectra of both complexes are dominated by 3MLCT states at room temperature in ethanolic solution, but at 77K the Ir-q exhibits the 3LC as the dominant emission state. The Ir-q complex shows one of the highest emission quantum yields, 11.5%, for a red emitter based on iridium(III) complexes in aerated PBS solution, with color coordinates (x;y) of (0.712;0.286). Moreover, both complexes display high potential to be used as a biological marker with excitation wavelengths above 400nm, high water solubility (Ir-p 1838μmol L-1, Ir-q 7601μmol L-1), and distinct emission wavelengths from the biological autofluorescence. Their cytotoxicity was analyzed in CHO-k1 cells by MTT assays, and the IC50 was estimated as being higher than 131μmol L-1 for Ir-p, and higher than 116μmol L-1 for Ir-q. Concentrations above 70% of viability were used to perform cell imaging by confocal and fluorescence microscopies and the results suggest that the complexes were internalized by the cell membrane and they are staining the cytoplasm region.

Delayed Replantation of Avulsed Permanent Maxillary Central Incisor with 2 Years of Follow Up: A Case Report

Abstract: Traumatic dental injuries are highly prevalent now a days. Present article discusses a case report of 13 years old male patient who reported with an dental emergency of left maxillary tooth avulsion. Patient kept the avulsed tooth in non physiologic media. Patient was treated as per the guidelines of interntional Association of Dental Traumatology. Replantation of avulsioned tooth is a preferred mode of treatment followed by physiologic splinting for a short period of time. Root canal therapy is required for the affected tooth in cases of delayed replantation. Patient’s clinical and radiographic follow up was done up to 2 years which showed patient remained asymptomic.

I Can’t Breathe, 2020: The Arts and Sciences of Oxygen

Abstract “I Can’t Breathe, 2020: The Arts and Sciences of Oxygen” proposes a literary criticism responsive to the existential crises of our time, working at the intersection of the linguistic, the physiological, and the atmospheric. Bringing together disciplines usually kept apart, this crisis-responsive genre remaps the input networks of literature, highlighting human agency on opposing ends of the spectrum. Both senses of the anthropogenic are at work here. Human causation is harm-mitigating as well as harm-bearing. Native American literature and pandemic responses provide a compelling archive for this approach. Often discussed only in terms of harm, this body of evidence in fact also shows harm partly alleviated, suggesting that reparative agency is possible, and that diversifying our investigative lens might be one way to begin. Joy Harjo—poet, musician, and former premed major—is a salient test case. “For Alva Benson” and “Ah, Ah,” like her blog posts, and like her saxophone playing, dwell on the respiratory chemistry of the human body as our precarious common ground. This chemistry integrates the arts and sciences of oxygen as physiological need, survival baseline, and expressive medium, speaking to the burden of the past, and holding out the perils and promise of the future.