scholarly journals Glycol Chitosan: A Water-Soluble Polymer for Cell Imaging and Drug Delivery

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4371 ◽  
Author(s):  
Fengming Lin ◽  
Hao-Ran Jia ◽  
Fu-Gen Wu
Keyword(s):  
Antimicrobial Agents ◽  
Tumor Imaging ◽  
Water Soluble ◽  
Glycol Chitosan ◽  
Water Soluble Polymer ◽  
The Past ◽  
Wide Range ◽  
Microbial Infections ◽  
Functional Biomaterials ◽  
Shed Light

Glycol chitosan (GC), a water-soluble chitosan derivative with hydrophilic ethylene glycol branches, has both hydrophobic segments for the encapsulation of various drugs and reactive functional groups for facile chemical modifications. Over the past two decades, a variety of molecules have been physically encapsulated within or chemically conjugated with GC and its derivatives to construct a wide range of functional biomaterials. This review summarizes the recent advances of GC-based materials in cell surface labeling, multimodal tumor imaging, and encapsulation and delivery of drugs (including chemotherapeutics, photosensitizers, nucleic acids, and antimicrobial agents) for combating cancers and microbial infections. Besides, different strategies for GC modifications are also highlighted with the aim to shed light on how to endow GC and its derivatives with desirable properties for therapeutic purposes. In addition, we discuss both the promises and challenges of the GC-derived biomaterials.

scholarly journals Antioxidant Properties of Fullerene Derivatives Depend on Their Chemical Structure: A Study of Two Fullerene Derivatives on HELFs

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Vasilina Sergeeva ◽  
Olga Kraevaya ◽  
Elizaveta Ershova ◽  
Larisa Kameneva ◽  
Elena Malinovskaya ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Chemical Structure ◽  
Antioxidant Properties ◽  
Water Soluble ◽  
Lung Fibroblasts ◽  
Human Embryonic Lung ◽  
Fullerene Derivatives ◽  
The Past ◽  
Wide Range ◽  
Short Times

Oxidative stress is a major issue in a wide number of pathologies (neurodegenerative, cardiovascular, immune diseases, and cancer). Because of this, the search for new antioxidants is an important issue. One of the potential antioxidants that has been enthusiastically discussed in the past twenty years is fullerene and its derivatives. Although in aqueous solutions fullerene derivatives have shown to be antioxidants, their properties in this regard within the cells are controversially discussed. We have studied two different water-soluble fullerene C60 and C70 derivatives on human embryonic lung fibroblasts at a wide range of concentrations. Both of them cause a decrease in cellular ROS at short times of incubation (1 hour). Their prolonged action, however, is fundamentally different: derivative GI-761 causes secondary oxidative stress whereas derivative VI-419-P3K keeps ROS levels under control values. To gain a better understanding of this effect, we assessed factors that could play a role in the response of cells to fullerene derivatives. Increased ROS production occurred due to NOX4 upregulation by GI-761. Derivative VI-419-P3K activated the transcription of antioxidant master regulator NRF2 and caused its translocation to the nucleus. This data suggests that the antioxidant effect of fullerene derivatives depends on their chemical structure.

scholarly journals From Nursery to Nursing Home: Emerging Concepts in Clostridioides difficile Pathogenesis

2020 ◽  
Vol 88 (7) ◽  
Author(s):  
Alexander B. Smith ◽  
Joshua Soto Ocana ◽  
Joseph P. Zackular
Keyword(s):  
Pharmaceutical Drugs ◽  
Human Gastrointestinal Tract ◽  
Content Type ◽  
The Past ◽  
Clostridioides Difficile ◽  
Wide Range ◽  
Pediatric Populations ◽  
The Impact ◽  
Shed Light

ABSTRACT Clostridioides difficile is a Gram-positive, spore-forming, anaerobic bacterium that infects the human gastrointestinal tract, causing a wide range of disorders that vary in severity from mild diarrhea to toxic megacolon and/or death. Over the past decade, incidence, severity, and costs associated with C. difficile infection (CDI) have increased dramatically in both the pediatric and adult populations. The factors driving this rapidly evolving epidemiology remain largely unknown but are likely due in part to previously unappreciated host, microbiota, and environmental factors. In this review, we will cover the risks and challenges of CDI in adult and pediatric populations and examine asymptomatic colonization in infants. We will also discuss the emerging role of diet, pharmaceutical drugs, and pathogen-microbiota interactions in C. difficile pathogenesis, as well as the impact of host-microbiota interactions in the manifestation of C. difficile-associated disease. Finally, we highlight new areas of research and novel strategies that may shed light on this complex infection and provide insights into the future of microbiota-based therapeutics for CDI.

Automated Method for Determining Amylase Activity in Serum and Urine

1973 ◽  
Vol 19 (10) ◽  
pp. 1187-1192 ◽  
Author(s):  
A Mazzuchin ◽  
C Weggel ◽  
C J Porter
Keyword(s):  
Amylase Activity ◽  
Water Soluble ◽  
Standard Curve ◽  
The Past ◽  
Automated Method ◽  
Wide Range ◽  
On Line ◽  
Starch Substrate ◽  
Suspended Substrate

Abstract We describe an automated procedure for determination of α-amylase activity in serum or urine by use of a water-insoluble chromogenic starch substrate (commercially available). "AutoAnalyzer" (Technicon Corp.) equipment is used in which the sample and suspended substrate are introduced simultaneously into the flow system. After incubation at 37 °C the water-soluble blue-starch breakdown products are filtered on-line across a cellulose nitrate membrane. Absorbance is measured at 630 nm, and the α-amylase activity read from a standard curve. The automated procedure has been in use for the past year and has been found to be an operationally simple, reproducible, and reliable method, which can be applied over a wide range of enzyme activity. Results of comparative studies with other α-amylase methods are also described.

Rogue people: on adversarial crowdsourcing in the context of cyber security

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Moradi ◽  
Qi Li
Keyword(s):  
Cyber Security ◽  
Research Study ◽  
Critical Issue ◽  
Dark Side ◽  
Content Type ◽  
The Past ◽  
Wide Range ◽  
Problem Solving Strategy ◽  
Solving Strategy ◽  
Shed Light

Purpose Over the past decade, many research works in various disciplines have benefited from the endless ocean of people and their potentials (in the form of crowdsourcing) as an effective problem-solving strategy and computational model. But nothing interesting is ever completely one-sided. Therefore, when it comes to leveraging people's power, as the dark side of crowdsourcing, there are some possible threats that have not been considered as should be, such as recruiting black hat crowdworkers for organizing targeted adversarial intentions. The purpose of this paper is to draw more attention to this critical issue through investigation of its different aspects. Design/methodology/approach To delve into details of such malicious intentions, the related literature and previous researches have been studied. Then, four major typologies for adversarial crowdsourced attacks as well as some real-world scenarios are discussed and delineated. Finally, possible future threats are introduced. Findings Despite many works on adversarial crowdsourcing, there are only a few specific research studies devoted to considering the issue in the context of cyber security. In this regard, the proposed typologies (and addressed scenarios) for such human-mediated attacks can shed light on the way of identifying and confronting such threats. Originality/value To the best of the authors' knowledge, this the first work in which the titular topic is investigated in detail. Due to popularity and efficiency of leveraging crowds' intelligence and efforts in a wide range of application domains, it is most likely that adversarial human-driven intentions gain more attention. In this regard, it is anticipated that the present research study can serve as a roadmap for proposing defensive mechanisms to cope with such diverse threats.

Silver nanoparticles: safety and efficiency for human health

2021 ◽  
Vol 19 (3) ◽  
pp. 247-257
Author(s):  
Yuliya A. Morozova ◽  
Dmitry S. Dergachev ◽  
Mikhail A. Subotyalov
Keyword(s):  
Silver Nanoparticles ◽  
Metal Nanoparticles ◽  
Human Health ◽  
Antimicrobial Agents ◽  
Inhibitory Effect ◽  
Modern Medicine ◽  
Laboratory Animals ◽  
High Biological Activity ◽  
The Past ◽  
Wide Range

Over the past few decades, nanoparticles of metals, and in particular silver, with a diameter of less than 100 nm have significantly expanded their field of application for various biomedical purposes. So, silver nanoparticles have great potential in a wide range of applications as antimicrobial agents, coatings for biomedical products, carriers for drug delivery, bioengineering, since they have discrete physical properties and wide biochemical functionality. Studies have shown that the size, morphology, stability and properties (chemical and physical) of metal nanoparticles are strongly influenced by the conditions of the experiment, the kinetics of the interaction of metal ions with reducing agents and the adsorption processes of the stabilizer with metal nanoparticles. This review aims to analyze the use of silver nanoparticles in modern medicine based on data from domestic and foreign literature over the past five years. The study confirmed the high biological activity of drugs with nanoserebrum as anti-inflammatory, antimicrobial agents, antifungals, the presence of an inhibitory effect on protozoa, antioxidant and anticancer effects, and substantiated the relevance of use in bioengineering and dentistry. However, rapid advances and advances in technology have led to concerns about the potential risk associated with the use and application of silver nanoparticles to human health and the environment. Therefore, this review attempts to characterize and quantify the potential harmful effects of silver nanoparticles on the health of laboratory animals and humans, and focuses on ways to neutralize or reduce the toxic effects of silver nanoparticles on the human body.

Review Essays

2006 ◽  
Vol 23 (3) ◽  
pp. 89-97
Author(s):  
Jackie Armijo
Keyword(s):  
Review Essay ◽  
Major Work ◽  
The Past ◽  
Chinese Studies ◽  
Wide Range ◽  
Relative Neglect ◽  
History Of ◽  
Chinese Scholars ◽  
Muslim Communities ◽  
Shed Light

Books Reviewed: Sachiko Murata, Chinese Gleams of Sufi Light: Wang Taiyu’s“Great Learning of the Pure and Real” and Liu Chih’s “Displaying theConcealment of the Real Realm.”Albany: SUNY Press, 2000; Maria Jaschokand Shui Jingjun, The History of Women’s Mosques in Chinese Islam: AMosque of Their Own. Richmond, UK: Curzon Press, 2000; Jean A. Berlie,Islam in China: Hui and Uyghurs between Modernization and Sinicization.Bangkok: White Lotus, 2004; Sheila Hollihan-Elliot, Muslims in China.Philadelphia: Mason Crest Publishers, 2006.With a population conservatively estimated at 20 million (and, according tosome sources, as high as 50 million), the Muslims of China remain one ofthe least studied and most misunderstood Muslim communities in theworld. After decades of relative neglect, however, over the past few yearsseveral books have been published that seek to shed light on differentaspects of the historic, religious, and contemporary lives of China’s Muslims.This review essay will survey four recent works written by a wide range ofscholars.Research on Islam in China has been hindered by many factors, includingthe difficulty of gaining expertise in both Chinese studies and Islamicstudies, learning both modern and classical Chinese and Arabic, the longstandingprejudices of Han Chinese scholars regarding the country’s minoritypeoples, together with the similarly long-standing prejudices of manywestern scholars regarding Islam. The earliest major work on the Muslimcommunities of China was published in 1910, by Marshall Broomhall of theChina Inland Mission. Titled Islam in China: A Neglected Problem, its mainpurpose was to educate Christian missionaries in China about the location,customs, and history of the indigenous Muslims in order to facilitate proselytizationactivities among them ...

scholarly journals Optimized Loading of Carboxymethyl Cellulose (CMC) in Tri-component Electrospun Nanofibers Having Uniform Morphology

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2524
Author(s):  
Motahira Hashmi ◽  
Sana Ullah ◽  
Azeem Ullah ◽  
Muhammad Akmal ◽  
Yusuke Saito ◽  
...  
Keyword(s):  
Carboxymethyl Cellulose ◽  
Water Solubility ◽  
Continuous Production ◽  
Weight Ratio ◽  
Electrospun Nanofibers ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Wide Range ◽  
Aqueous Conditions ◽  
Water Holding

Cellulose is one of the most hydrophilic polymers with sufficient water holding capacity but it is unstable in aqueous conditions and it swells. Cellulose itself is not suitable for electrospun nanofibers’ formation due to high swelling, viscosity, and lower conductivity. Carboxymethyl cellulose (CMC) is also super hydrophilic polymer, however it has the same trend for nanofibers formation as that of cellulose. Due to the above-stated reasons, applications of CMC are quite limited in nanotechnology. In recent research, loading of CMC was optimized for electrospun tri-component polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and carboxymethyl cellulose (CMC) nanofibers aim at widening its area of applications. PVA is a water-soluble polymer with a wide range of applications in water filtration, biomedical, and environmental engineering, and with the advantage of easy process ability. However, it was observed that only PVA was not sufficient to produce PVA/CMC nanofibers via electrospinning. To increase spinnability of PVA/CMC nanofibers, PVP was selected as the best available option because of its higher conductivity and water solubility. Weight ratios of CMC and PVP were optimized to produce uniform nanofibers with continuous production as well. It was observed that at a weight ratio of PVP 12 and CMC 3 was at the highest possible loading to produce smooth nanofibers.

scholarly journals Preparation of PVA Fluorescent Gel and Luminescence of Europium Sensitized by Terbium (III)

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 893
Author(s):  
Yifan Wei ◽  
Zhengquan Fu ◽  
Hao Zhao ◽  
Ruiqi Liang ◽  
Chengyu Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Film Formation ◽  
Electronic Configuration ◽  
Rare Earth Ions ◽  
Water Soluble ◽  
Fluorescence Properties ◽  
Hydroxyl Groups ◽  
Water Soluble Polymer ◽  
Quenching Effect ◽  
Wide Range

Polyvinyl alcohol (PVA) gel has a very wide range of applications in agriculture, military, industry, and other fields. As a widely used water-soluble polymer, PVA has good mechanical properties, excellent spinnability, good hydrophilicity, remarkable physical and chemical stability, good film formation, is non-polluting, and exhibits good natural degradation and biocompatibility. It is an ideal gel preparation material. Incorporation of rare-earth elements into PVA polymers can be used to prepare rare-earth luminescent gel materials. Results show that the luminescent efficiency of complexes is mainly related to their structure, ligand substituents, synergists, and the electronic configuration of doped rare-earth ions. Fluorescent gel films were prepared by adding europium, terbium, and europium/terbium co-doped into PVA, and their fluorescence properties were compared and analyzed. It was found that, in addition to the above factors, the sensitization of terbium to europium, and the fluorescence-quenching effect of hydroxyl groups, will influence the fluorescence properties. This has opened a new route for the application of rare-earth materials and may have value in the field of new materials.

Modification of Near-Wall Turbulent Structure in Channel Flow by Dosing a Small Amount of Polymer Solution

2017 ◽  
Author(s):  
Yushi Okamura ◽  
Tomohiro Kurose ◽  
Yasuo Kawaguchi
Keyword(s):  
Velocity Distribution ◽  
Polymer Solution ◽  
Polymer Concentration ◽  
Water Soluble ◽  
Polymer Additives ◽  
Normal Velocity ◽  
Water Soluble Polymer ◽  
Low Speed ◽  
Wide Range ◽  
Near Wall

The phenomenon known as Toms effect can impart viscoelasticity to a water flow when a small amount of water-soluble polymer is added. The resulting viscoelastic fluid generates viscoelastic stress in the flow, dramatically reducing the turbulent stress. In this study, the spatial distribution of velocity is measured using a stereo-PIV method in the streamwise-spanwise plane parallel to the wall. Modification of the near wall turbulence by the polymer solution blown slowly from a permeable wall was investigated by analyzing the velocity distribution acquired by stereo-PIV measurements. Experimental results reveal that streamwise local mean velocity decreases as the dosed polymer concentration increases. The skewness factor at this height shifts from 0 to positive by adding the polymer, which indicates intensified turbulent coherent structure. Moreover, the spatial two-point correlation function calculated from streamwise velocity fluctuations maintains its high correlation with the streamwise direction. It is consistent with the finding from the instantaneous velocity distribution, which shows that the flection of low-speed streaks is suppressed. Next, it is revealed that the normal velocity at the wall for low-speed fluid is decreased dramatically by polymer additives. Moreover, applying the quadrant analysis, it is confirmed that ejection events are suppressed with decreasing normal velocity at the wall. Suppression of ejection motion affects to the turbulence in the log law layer. We conclude that this is one reason that turbulence is suppressed in a wide range of the shear layer by polymer additives present only in the vicinity of the wall.

Crosslinking of Guar and Guar Derivatives

SPE Journal ◽  
2007 ◽  
Vol 12 (03) ◽  
pp. 316-321 ◽  
Author(s):  
Cuiyue Lei ◽  
Peter E. Clark
Keyword(s):  
Polymer Solution ◽  
Critical Concentration ◽  
Polymer Concentration ◽  
Water Soluble ◽  
Solution Behavior ◽  
Water Soluble Polymer ◽  
Important Indicator ◽  
Low Concentrations ◽  
Wide Range ◽  
Overlap Concentration

Summary Crosslinking of guar and guar derivatives has played a major role in improving stimulation of oil and gas wells. While crosslinking has been used for a number of years, many facets of crosslinked systems are still not well understood. Part of the problem is that the traditional methods of determining the properties of crosslinked fluids work well for obtaining the data necessary for treatment design, but yield little insight into the nature of the crosslinked system. A good example of this is found in the development of low polymer concentration crosslinked gels. These gels are important because they lower costs and help to minimize formation damage. In this paper, methods for predicting crosslinkability at low concentrations are reported. The polymer literature is filled with methods for characterizing polymer solutions almost none of which find wide use in the development of crosslinked fracturing fluids. Dawson et al. (2000) first reported that the concentration at which a polymer solution transitions from dilute to semidilute could be used as a method for determining the potential for low concentration crosslinking in guar or guar-derivative solutions. To test this assertion, we have conducted a series of experiments that not only shows that the dilute-semidilute transition concentration is an important indicator for the polymers used in this study, but also presents a framework for exploring the potential of other polymer systems. These experiments show conclusively that low-polymer concentration crosslinking is strongly related to the value of the critical overlap concentration, c*. Both the critical overlap concentration and the critical crosslinking concentration increase in the order guar-3 < CMG < CMHPG < guar < HPG. In addition, we show that the critical crosslinking concentration for the range of polymer-crosslinking systems studied is correlated to the critical overlap concentration (). A strong case is presented for the ability to crosslink at low concentrations is a strong function of the polymer type and a weak function of the crosslinker type. Introduction Water-soluble polymers have been used for a number of years as thickening agents for stimulation fluids. Crosslinking was developed to improve the performance of these materials without increasing polymer concentration. Over the years, a number of different crosslinking agents have been used with success. There are several good discussions of polymer and crosslinking systems available (Economides and Nolte 1989; Gidley et al. 1989), and it is not the purpose of this paper to expand these discussions. Rather, we will approach the problem of crosslinking from the prospective of the molecular or solution properties that control or influence crosslinking. When a water-soluble polymer is hydrated, the viscosity of the resulting solution increases as a function of concentration. Starting at low concentrations and building to high concentrations, the viscosity appears to exhibit an exponential increase. This phenomenon has been studied for a wide range of polymer—solvent systems and seems to be universal. Early work divided the viscosity—concentration curve into two regions (Menjivar 1986; Robinson et al. 1982) that were separated at a critical concentration labeled c*. As the understanding of polymer solution behavior progressed and more sensitive instruments and experimental techniques were developed, the solution behavior was determined to be more complex (Rubinstein and Colby 2003).

Sign in / Sign up

Export Citation Format

Share Document