Controlled Release ot Methvl Salicvlate in ChitosanPoli[N-Isopropvlacrvlamide] Semi-Interpenetrating Networks

A semi-interpenetrating network (semi-IPN) was produced by polymerizing Nisopropylacrylamide (NIP AAm) in the presence of chitosan and cross-linking agent, ethylene glycol dimethacrylate (EGDMA). The resulting material did not swell as much as poly(N-isopropylacrylamide) (piPAAm), but still showed temperature- and pHresponsiveness. Swelling and differential scanning calorimetry (DSC) experiments showed that the lower critical solution temperature (LCST) of the material was at 31 °C. The semiIPN was swollen below 30 °C but started to collapse at this temperature. This is in the same range as the LCST of carrageenan-piPAAm semi-IPN. The chitosan-piPAAm semi-IPN was in a collapsed state and reached maximum swelling at pH 9 whereas pure piP AAm and pure chitosan both became swollen at a lower pH. Methyl salicylate was absorbed by the semi-IPN. Its release was monitored with respect to temperature. The temperature-responsive release of methyl salicylate was more pronounced at the LCST of31° C

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Metal Absorption Capacities of κ-Carrageenan Blends

Lead, cadmium and zinc were allowed to bind to the sulfated galactan units of κ-carrageenan by preparing a mixture of 1% κ-carrageenan in 0.1 M Pb(NO3)2 and Cd(NO3)2. and equilibrating overnight. The Pb2+ concentration in the supernatant was determined initially using potentiometric stripping analysis (PSA) but the concentration range for this application was much higher. The Pb2+ and Cd2+ concentrations were then determined by atomic absorption spectroscopy (AAS). The concentration of bound metal was calculated by substracting the amount of metal in the supernatant from the amount in the original solution. Results show that Pb2+ and Cd2+ in solution is complexed with the carrageenan. However, complexation with various carrageenan-chitosan and carrageenan-poly-N-isopropyl acrylamide (N-IPAAm) blends changes the amount of bound metal, indicating that the polyelectrolyte blend can be used to control the binding capacity of the biopolymers. AFM micrographs show some change in the topology of the various polymer systems. Thermal analysis, FTIR and GPC were also used to characterized the polymer blends

Structural Changes in Insulin at a Soft Electrochemical Interface

Understanding the interaction of proteins at interfaces, which occurs at or within cell membranes and lipoprotein vesicles, is central to our understanding of protein function. Therefore, new experimental approaches to understand how protein structure is influenced by protein-interface interactions are important. Herein we build on our previous work exploring electrochemistry at the interface between two immiscible electrolyte solutions (ITIES) to investigate changes in protein secondary structure that are modulated by protein-interface interactions. The ITIES provides an experimental framework to drive protein adsorption at an interface, allowing subsequent spectroscopic analysis (e.g., Fourier transform infrared spectroscopy) to monitor changes in protein structure. Here, we reveal that the interaction between insulin and the interface destabilizes native insulin secondary structure, promoting formation of α helix secondary structures. These structural alterations result from protein-interface rather than protein-protein interactions at the interface. Although this is an emerging approach, our results provide a foundation highlighting the value of the ITIES as a tool to study protein structure and interactions at interfaces. Such knowledge may be useful to elucidate protein function within biological systems or to aid sensor development

Comparison of water retention and thermal properties of various polysaccharides, their derivatives and blends

The Philippines has an abundance of polysaccharide resources such as different forms of cellulose (nata de coco, kapok, ramie, banana fiber, etc.). This paper presents some polysaccharides hydrogels, which have numerous higher value applications. Hydrogel properties are related to water retention property, which in turn can be associated with thermo- or pH-sensitivity. These properties can be modified through derivatization. Acetylation significantly decreases the solubility of the polysaccharide in water and its ability to form hydrogels. The carboxymethyl group decreases water retention without losing its hydrophilicity altogether. Semi-interpenetrating networks, on the other hand, can have controlled properties depending on the amount of crosslinking. These are observed with the help of thermal analysis and equilibration experiments

Distance-Based Tear Lactoferrin Assay on Microfluidic Paper Device Using Interfacial Interactions on Surface-Modified Cellulose

“Distance-based” detection motifs on microfluidic paper-based analytical devices (μPADs) allow quantitative analysis without using signal readout instruments in a similar manner to classical analogue thermometers. To realize a cost-effective and calibration-free distance-based assay of lactoferrin in human tear fluid on a μPAD not relying on antibodies or enzymes, we investigated the fluidic mobilities of the target protein and Tb³⁺ cations used as the fluorescent detection reagent on surface-modified cellulosic filter papers. Chromatographic elution experiments in a tear-like sample matrix containing electrolytes and proteins revealed a collapse of attractive electrostatic interactions between lactoferrin or Tb³⁺ and the cellulosic substrate, which was overcome by the modification of the paper surface with the sulfated polysaccharide ι-carrageenan. The resulting μPAD based on the fluorescence emission distance successfully analyzed 0–4 mg mL^–1 of lactoferrin in complex human tear matrix with a lower limit of detection of 0.1 mg mL^–1 by simple visual inspection. Assay results of 18 human tear samples including ocular disease patients and healthy volunteers showed good correlation to the reference ELISA method with a slope of 0.997 and a regression coefficient of 0.948. The distance-based quantitative signal and the good batch-to-batch fabrication reproducibility relying on printing methods enable quantitative analysis by simply reading out “concentration scale marks” printed on the μPAD without performing any calibration and using any signal readout instrument

Distance-Based Tear Lactoferrin Assay on Microfluidic Paper Device Using Interfacial Interactions on Surface-Modified Cellulose

“Distance-based” detection motifs on microfluidic paper-based analytical devices (μPADs) allow quantitative analysis without using signal readout instruments in a similar manner to classical analogue thermometers. To realize a cost-effective and calibration-free distance-based assay of lactoferrin in human tear fluid on a μPAD not relying on antibodies or enzymes, we investigated the fluidic mobilities of the target protein and Tb³⁺ cations used as the fluorescent detection reagent on surface-modified cellulosic filter papers. Chromatographic elution experiments in a tear-like sample matrix containing electrolytes and proteins revealed a collapse of attractive electrostatic interactions between lactoferrin or Tb³⁺ and the cellulosic substrate, which was overcome by the modification of the paper surface with the sulfated polysaccharide ι-carrageenan. The resulting μPAD based on the fluorescence emission distance successfully analyzed 0–4 mg mL^–1 of lactoferrin in complex human tear matrix with a lower limit of detection of 0.1 mg mL^–1 by simple visual inspection. Assay results of 18 human tear samples including ocular disease patients and healthy volunteers showed good correlation to the reference ELISA method with a slope of 0.997 and a regression coefficient of 0.948. The distance-based quantitative signal and the good batch-to-batch fabrication reproducibility relying on printing methods enable quantitative analysis by simply reading out “concentration scale marks” printed on the μPAD without performing any calibration and using any signal readout instrument