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This topic is for all general discussion regarding the current COVID-19 pandemic. There are of course numerous other related topics for discussing specific aspects of this pandemic in more detail. And there are other parts of this forum for more 'off-topic' discussions.

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5 minutes ago, Velma said:

Never. Level 0 in Scotland, which no-one is in, will be "almost normality."

 

 

At Level 0:

  • you can meet socially in groups:
    • of up to 8 people from 4 households in your home or theirs – and can stay overnight
    • of up to 10 people from 4 households in an indoor public place like a café, pub or restaurant
    • of up to 15 people from 15 households outdoors
  • under 12s do not count towards the total number of people or households meeting outside but count towards the household numbers indoors
  • you do not need to physically distance from family and friends in a private home
  • you can travel anywhere in Scotland in Levels 0, 1 or 2 but must not enter a Level 3 or 4 area unless for a permitted reason
  • you can travel anywhere in England, Wales, Northern Ireland, the Isle of Man or the Channel Islands - before you travel you must check the travel rules in those countries
  • you can provide informal childcare, for example to look after a grandchild
  • up to 200 people can attend weddings and funerals
  • tradespeople can carry out any work in your home such as painting, decorating or repairing
  • you should work from home where possible

 

God its hilarious. Like one of those bonkers maths tests we used to get at school. Clowns.

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50 minutes ago, oddsnsods said:

 

 

More actors for the cult in the melting pot of madness, I mean, its like they sought out the most lefty looking loons they could find for that bull crap.

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Posted (edited)
30 minutes ago, Human10 said:

This new variant attacks hair... BoJo needs to watch out.

On a side note,we don't see much of his latest kid, he never seems to mention him much either, wonder if he would volunteer him for Vax trials seeing as he has so much trust in the science?...Perhaps because it was just a dolly...tallest baby I've ever seen looks about 3ft tall!

33460602-0-image-a-69_1600734950529.jpg

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10 minutes ago, Outsider said:

Haha, would love to see him do one of his 5pm group think sessions with bright blue hair....then I'd watch.

Imagine his speech - 'look what it done to my hair'! With breathing through ass nothing can surprise me now.

 

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Posted (edited)
4 hours ago, BossCrow said:

 

(edit) Forgot to mention - 3.3M views on the video!

 

Is that some sort of parody/satire from a comedian?  If so, it's quite amusing.  It's not for real, surely?  Genuine question because I can no longer distinguish between the two things.

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1 hour ago, FrankVitali said:

Latest from Reiner Fuellmich. 

 

 

 

 

 

 

This is where I must politely disagree with Ziggy,  Reiner has very good credentials. He is teamed up with 1000s of lawyers worldwide, he has been working on this case since around March 2020 with his team and Vivianne Fischer. He was the chap who sued VW over the diesel emissions scandal and also he has successfully sued Deutsche Bank.  I know the courts are swung the wrong way, but soon this is going to be so big that it cannot be hidden.

 

I take much pleasure in watching all of Reiners' videos, even though they are very lengthy. But.. knowledge is everything.

 

I repeat, knowledge is everything.

 

This is exactly what I am doing differently than the sheeple. I am spending hours, hours and hours of my time absorbing knowledge from people like these, all the ones who are being censored.

 

Part 1 is here:

 

 

 

 

 

Part 2 is here:

 

 

 

 

I don't mind you disagreeing with me my friend.

I'd love to be wrong and you right, but the bottom line is, in my opinion, the courts, just like the politicians, ultimately do as the vermin tell them.

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10 minutes ago, Pina Colada said:

Makes you wonder if they are bringing forward the second jabs just before the deluge of vaccine injuries and deaths becomes mainstream?

Just putting this out there... but I have a neighbour I can't stand. She's beyond salvation in any known metric. In the context of vaccines, I'm sitting wondering - hoping - she's had both doses.

 

Bigger picture, does anyone really think these so-called vaccines will really decimate the population -?  I still can't fathom out their end-game. Do they want to kill us? Or do they want to reduce us to obedient consumer-zombies? 

 

As I said, bigger picture - what's this about?

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Posted (edited)
3 hours ago, oddsnsods said:

Bodger: So yeah that jab you got doesn't immunise diddly squat...

 

Of course you will need your freedumb passport to stop you from spreading the new variant.🤔

 

In about 9 years with enough booster shots we will have this pandemic under control.

 

8-27-2007-23.jpg

 

 

 

Still it's all for the good of the country I suppose - Live Organ Transplants by Monty Python

 

And...

 

It's better being dead than getting Covid

 

Remember:

 

The Government and SAGE recommend 

 

Six Feet Under for proper social distancing.

 

Drop dead you proles and useless eaters,

 

End transmission!

 

 

 

 

 

 

 

 

 

 

 

 

 

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3 minutes ago, Dickwan said:

Just putting this out there... but I have a neighbour I can't stand. She's beyond salvation in any known metric. In the context of vaccines, I'm sitting wondering - hoping - she's had both doses.

 

Bigger picture, does anyone really think these so-called vaccines will really decimate the population -?  I still can't fathom out their end-game. Do they want to kill us? Or do they want to reduce us to obedient consumer-zombies? 

 

As I said, bigger picture - what's this about?

I really cant tell yet how many people will parish do to this vaccine, personally i think it is preparing us for perpetual vaccines and leaving us with zero freedoms and personal income eventually.

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2 minutes ago, TwopackShugar said:

I really cant tell yet how many people will parish do to this vaccine, personally i think it is preparing us for perpetual vaccines and leaving us with zero freedoms and personal income eventually.

 

I've been thinking this over too and this seems likely - a nation ( or global superstate) of penniless pincushions.

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4 minutes ago, TwopackShugar said:

I really cant tell yet how many people will parish do to this vaccine, personally i think it is preparing us for perpetual vaccines and leaving us with zero freedoms and personal income eventually.

I think you're bang-on TPS. It seems - at this stage - to be about compliance. Who knows what comes next (although it's pretty fucking obvious they're going to want to cull the herd longer term).

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3 minutes ago, pete675 said:

 

I've been thinking this over too and this seems likely - a nation ( or global superstate) of penniless pincushions.

I reckon the great reset is playing out. 
completely destroy independent income, roll out universal basic income and bring about total dependence on the state who will then control everything and everyone. 
 

As mad as this all sounded a year ago, I really can’t see any other reason for any of this. 

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53 minutes ago, Pina Colada said:

Makes you wonder if they are bringing forward the second jabs just before the deluge of vaccine injuries and deaths becomes mainstream?

They are fine in Israel after second dose (at least most of them). It would rather work as a booster for a non-existent variant... Right after they will start jabbing there will be rise in cases and when they will be done it will be next spectacular success of a vaccine... 🥴

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Posted (edited)

India has an average death rate of around (~) 26000 per day 

Nothing to see hear unless your the media and you want to induce fear in literal captive audience!

 

https://www.statista.com/statistics/580178/death-rate-in-india/

https://www.medindia.net/patients/calculators/pop_clock.asp

 

https://worldpopulationreview.com/countries/deaths-per-day  shows India  ~27000/day with china at just over 29000/day and UK at 1753 per day or 639845 per year (2019)

 

daily mail

https://www.dailymail.co.uk/news/article-9140499/More-600-000-people-died-England-Wales-2020.html

ONS figures show there were 608,002 deaths in England and Wales in 2020 according to DM.

 

 

There is a enormous inconsistency in comparative figures and overall nothing seemed out of the ordinary for 2020 except for official statistical skullfuckery & induced fear.

eg  https://www.statista.com/statistics/281488/number-of-deaths-in-the-united-kingdom-uk/ - not a gov website but observe the trash they peddle!

Media and corporates ALL lie about everything and are inconsistent throughout except for lies.

 

25000 hospital patients were moved in March to care homes and put on end of life pathway and denied medical treatment, as were the remaining care home residents!

Morphine & analogue sales were doubled in 2020 for care homes!

https://architectsforsocialhousing.co.uk/2021/01/27/lies-damned-lies-and-statistics-manufacturing-the-crisis/ is a lengthy summary!

https://www.independent.co.uk/news/uk/home-news/coronavirus-uk-care-homes-test-cases-deaths-nao-a9562336.html

 

Just so no one forgets what these bastards have done and continue to do.

Edited by zarkov
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3 hours ago, Woodsman said:

So some European countries are opening again but it’s still ILLEGAL to leave England on HOLIDAYS according to the UK Government website. (Not a reasonable excuse)

 

Now at the moment should one leave (with a reasonable excuse from the list) a virus test has to be done 24hrs before and then again upon arrival and then much isolation even when negative. (Noses will be like a pin cushion) Is there a non invasive test method that is safe and reliable? How about blood tests? Scandinavians and Dutch officials refuse NHS tests as evidence of no virus. (I think because this would mean it’s citizens would be stuck at the ports with a fake positive and have to isolate 10 days in UK) 

 

I did read should one be able to prove had the virus and had recovered then no need for tests and isolation.  

 

How would anyone prove they had the virus...if they can`t prove the virus exists... Maybe they can re-use the PCR test like Kary Mullis said and make something out of nothing.

 

I`d love to know which anti-bodies they are claiming are active in blood from C19...it`s mesmerizing how they can make up shit, sell it as a contagion and people buy it. They offer to pay 50 pounds for people to get a test that doesn`t test for anything they say it does... whether for free or being paid - the people line up to be plunged in the head with an extra long Q Tip as it scrapes as near to their brain ( or an excuse for one in many cases) as possible.

 

Then they tell the people they could die from this invisible unidentified contagion and if they dont get immunized with a creation made from aborted fetus cells, monkey, hydrogel and the other crap, they will be responsible for killing off mankind with their careless behaviour.

 

Most seem to have bought into the mysterious virus initially - but are slightly slower to accept the so called immunization, so the governments soldier ants  get motivated to coerce the people, they go door to door dressed in hospital garb, or dress up like idiots- even as a singing syringe,  and try to persuade people with doughnuts, or fries and a burger. 

 

Then those who have been attacked with the pointy end get really weird side effects, which they quickly tell about  to friends. Not content with being sick themselves with anything from a sore eye, droopy chops, through loss of  feeling sensations to upset stomach and the trots, they then want to make sure those they care about suffer in the same way and inquire when they are going to sacrifice themselves to the holy prick. They cant believe anyone would find this whole fiasco to be anything other than a genuine pandemic - they are absolutely oblivious to the fact that the Circus has come to town and they have been mind controlled to be in on the Act.

 

If anyone had told us this even 2 years ago - they would have been called conspiracy theorists in tin foil hats.

 

What is more puzzling...is how do some people not succumb to the mind control. What is different about most of us in this forum for example?

 

 

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Posted (edited)

This is a bit lengthy but illustrates the advanced no limit fuckery these so called researchers take part in.

Apparently called progress! (for the mentally disturbed).

 

Options - submit to medical experimentation with endless complications and follow-up treatments and possible death

or

take responsibility for yourself & follow a natural balanced diet with abundant minerals and vitamins and get adequate sunlight and fast when toxic or need to heal.

 

From PSI

Advances On Magnetic Sensitive Hydrogels In Tissue Engineering

Published on May 14, 2021

Written by nih.gov

 

Magnetic-hydrogel-Frontiers.jpg?resize=5

Image: Frontiers

Tissue engineering, a branch of regenerative medicine, refers to the application of supporting cells, material scaffolds, bioactive molecules, or their combinations to repair and reconstruct tissues and organs.

 

Tissue engineering is a promising strategy for the repair and regeneration of damaged tissues or organs. Biomaterials are one of the most important components in tissue engineering. Recently, magnetic hydrogels, which are fabricated using iron oxide-based particles and different types of hydrogel matrices, are becoming more and more attractive in biomedical applications by taking advantage of their biocompatibility, controlled architectures, and smart response to magnetic field remotely.

In this literature review, the aim is to summarize the current development of magnetically sensitive smart hydrogels in tissue engineering, which is of great importance but has not yet been comprehensively viewed.

 

Hydrogels have been shown to be one of the most applicable biomaterials in tissue engineering (Kabu et al., 2015; Madl et al., 2017, 2019; Deng et al., 2019) mainly attributed to their inner 3D network microstructures, moderate biocompatibility, and good water content feature, which are analogous with those of the natural tissue (Cui Z.K. et al., 2019; Zhu et al., 2019).

Meanwhile, hydrogel-based drug delivery systems for numerous therapeutic agents, with high water content, low interfacial tension with biological fluids, and soft consistency, have been shown to be more stable, economical, and efficient in comparison with conventional delivery systems (Li and Mooney, 2016; Moore and Hartgerink, 2017; Cheng et al., 2019; Fan et al., 2019; Zheng et al., 2019).

Considering the above advantages, hydrogels have been conducted into the biomedical application to provide a tunable three-dimensional scaffold for cell adhesion, migration, and/or differentiation, and they could also be designed as the platform for the controlled release of cytokines and drugs in tissue engineering and drug delivery (Huang et al., 2017; Jiang et al., 2017; Hsu et al., 2019; Wei et al., 2019; Zheng et al., 2019).

Hydrogel first appeared in a literature as early as in 1894 (Van Bemmelen, 1894); however, the “hydrogel” described at that time was not the same form of hydrogels used nowadays; it was a type of a colloidal gel made from inorganic salts. Later on, the term “hydrogel” was applied for describing a 3D network of hydrophilic native polymers and gums by physical or chemical crosslinking approaches, and its application heavily relied on water availability in the environment (Lee et al., 2013).

The current generation of hydrogel in the biological field was first performed by Wichterle and LÍm (1960), indicating that glycoldimethacrylate-based hydrophilic gels exhibited adjustable mechanical properties and water content. From then on, more and more hydrogels have been developed, and the smart hydrogels were then introduced in different fields of biological science, such as drug delivery, bioseparation, biosensor, and tissue engineering.

Smart hydrogels are described as they respond directly to the changes of environmental conditions (Wichterle and LÍm, 1960), and numerous studies of smart hydrogels in the applications of nanotechnology, drug delivery, and tissue engineering have been put into effect in the last few decades (Li X. et al., 2019; Li Z. et al., 2019; Zhang Y. et al., 2019).

Recently, magnetically responsive hydrogel, as one kind of smart hydrogels, has been introduced into biomedical applications in improving the biological activities of cells, tissues, or organs. This is mainly attributed to its magnetic responsiveness to external magnetic field and obtaining functional structures to remotely regulate physical, biochemical, and mechanical properties of the milieu surrounding the cells, tissues, or organs (Abdeen et al., 2016; Antman-Passig and Shefi, 2016; Rodkate and Rutnakornpituk, 2016; Bannerman et al., 2017; Omidinia-Anarkoli et al., 2017; Xie et al., 2017; Silva et al., 2018; Tay et al., 2018; Wang et al., 2018; Bowser and Moore, 2019; Ceylan et al., 2019; Luo et al., 2019).

Recent studies have represented that magnetic hydrogel could act as an excellent drug release and targeting system. For example, Gao et al. (2019) fabricated a magnetic hydrogel based on ferromagnetic vortex-domain iron oxide and suggested that this unique magnetic hydrogel could significantly suppress the local breast tumor recurrences.

Manjua et al. (2019) developed magnetic responsive poly(vinyl alcohol) (PVA) hydrogels, which could be motivated by ON/OFF magnetic field and non-invasively regulated protein sorption and motility, indicating a promising application for tissue engineering, drug delivery, or biosensor system.

Moreover, a composite magnetic hydrogel prepared by a combination of a self-healing chitosan/alginate hydrogel and magnetic gelatin microspheres could be used as a suitable platform for tissue engineering and drug delivery (Chen X. et al., 2019a). In comparison with magnetic hydrogels, various kinds of smart biomaterials (e.g., scaffolds, biofilms, other smart hydrogels), which are activated by external stimuli, such as light, pH, temperature, stress, or charge, have great potential in biomedical applications (Chen H. et al., 2019; Cui L. et al., 2019; Wu C. et al., 2019; Zhao et al., 2019; Yang et al., 2020).

However, the long response time and less precisely controlled architectures of these stimuli-responsive smart biomaterials are the two main limitations.

Magnetic hydrogels are usually made of a matrix hydrogel and a magnetic component that was incorporated into the matrix. Recently, superparamagnetic and biocompatible iron oxide-based magnetic nanoparticles (MNPs) are most commonly incorporated into polymer matrices to prepare magnetically responsive hydrogels for their application in tissue engineering, such as γ-Fe2O3, Fe3O4, and cobalt ferrite nanoparticles (CoFe2O4) (Zhang and Song, 2016; Rose et al., 2017; Ceylan et al., 2019).

Magnetite (Fe3O4) is a compound of two kinds of iron sites with 1/3 of Fe2+ and 2/3 of Fe3+. The intervalence charge transfer between Fe2+ and Fe3+ induces absorption throughout the ultraviolet–visible spectral region and the infrared spectral region, which generates a black appearance in color (Barrow et al., 2017). Maghemite (γ-Fe2O3), with a brown-orange color pattern, is an oxidative product of magnetite (Fe3O4) when the temperature is below 200°C (Tang et al., 2003).

In terms of CoFe2O4, previous studies have shown that the concentration of 20% was toxic, whereas at 10% the toxicity was insignificant. Moreover, 10% (w/w) of CoFe2O4 could maximize magnetic response because of numerous amounts of nanoparticles, developing biocompatible biomaterials (Goncalves et al., 2015; Brito-Pereira et al., 2018). For example, Hermenegildo et al. (2019) designed a novel CoFe2O4/Methacrylated Gellan Gum/poly(vinylidene fluoride) hydrogel, which created a promising microenvironment for tissue stimulation.

n this literature review, we aim to summarize the preparation methods and current development of magnetically sensitive smart hydrogels in tissue engineering, especially in bone, cartilage, and neural tissue engineering, which are of great importance but have not yet been comprehensively reviewed.

The Fabrication Processing Of Magnetic Hydrogels

Magnetic hydrogels are made of composite materials that possess biocompatibility, biodegradation, and magnetic responsiveness. The characteristics of magnetic hydrogels depend upon several issues, including the magnetic particles and the component of hydrogels used, the magnetic particles and hydrogels’ concentration, and the size and uniformity of magnetic particles within the hydrogels.

There are mainly three preparation methods of fabricating magnetic hydrogels: (i) blending method; (ii) in situ precipitation method; (iii) grafting-onto method. The scheme for the main three syntheses of the magnetic hydrogels is shown in Figure 1.

Figure-1.jpg?resize=550%2C371&ssl=1

Figure 1

The Blending Method

In the blending approach, magnetic particles, and hydrogels are fabricated separately. The magnetic particles are normally synthesized using a coprecipitation process. The resulting magnetic particles are then stored in an aqueous or oily liquid to prevent aggregation and oxidization. Finally, the solution of magnetic particles is mixed with the hydrogel solution for crosslinking, and the magnetic particles are encapsulated into the hydrogels.

Tóth et al. (2015) modified the surface of MNPs (magnetite) with biocompatible chondroitin-sulfate-A (CSA) to develop CSA-coated MNPs. Then, CSA-coated MNPs were dispersed into hyaluronate (HyA) hydrogel to prepare the HyA-based magnetic hydrogel. It was found that the HyA-based magnetic hydrogel could be conducted in the treatment of osteoarthritis by the intra-articular injection approach.

Shi et al. (2019) fabricated bisphosphonate (BP)-modified hyaluronic acid (HA)/Fe3O4 magnetic hydrogel. This novel magnetic hydrogel showed outstanding compatibility and slow degradation in vivo and held the expectation of safety in clinic usage.

The blending method has several advantages in the preparation of magnetic hydrogels. Firstly, magnetic particles (e.g., MNPs, micrometer-iron oxides) with homogenous size in hydrogels can be obtained by modifying the stirring speed, the concentration of the substances, and the fabrication period. Secondly, the preparation process is easy to be performed since the preparation and crosslinking of magnetic particles are conducted separately.

However, there are also some limitations that could be addressed in the future, including the asymmetric distribution of magnetic particles within the hydrogels and the diffusion of magnetic particles when the magnetic hydrogels were submerged in a solution.

In Situ Precipitation Method

In the process of the in situ precipitation, the network of the hydrogels acts as a chemically reactive substance, within which the iron ions from inorganic salts in hydrogels react with alkali solutions (e.g., NH3·H2O, NaOH; Arias et al., 2018; Liu et al., 2019) to prepare the magnetic particles. In detail, the hydrogels are firstly prepared through polymerization, temperature change, or a crosslinking reaction.

Then, magnetite precursors containing iron(III) and iron(II) at a molar ratio of 1:2 are added into the hydrogels to obtain a homogenous solution. Finally, the mixture is immersed in an alkali solution to induce the crystallization of magnetite. The magnetic particles are incorporated into the hydrogels according to the following hydrolytic reaction (2 Fe3+ + Fe2+ + OH– → Fe3O4 + 4 H2O). Wang et al. (2018) designed a magnetic chitosan hydrogel by adding MNPs via in situ synthesis during chitosan hydrogel formation.

The resulting magnetic hydrogel showed a magnetic response and improved morphological and mechanical features, including the homogenous distribution of MNPs and excellent wettability. Moreover, the mechanical properties (such as the compression strength, the yield strength, and the probe displacement) of the magnetic hydrogel was enhanced with the rising concentration of MNPs from 0 to 15 wt%, which was attributed to the crosslinking role of MNPs in the process.

Under low-frequency alternating magnetic field (LAMF) exposure, the magnetic hydrogel laden with drugs exhibited a pulsatile drug release profile. In addition, the in situ fabricated MNPs in the magnetic hydrogel had excellent biocompatibility and no acute toxicity on MG-63 cells (human osteosarcoma cell line). Liu et al. (2019) fabricated polydopamine (PDA)-chelated carbon nanotube (CNT)-Fe3O4 (PFeCNT) nanohybrids into the acrylamide hydrogel via an in situ precipitation method to generate the PFeCNT hydrogel.

This magnetic hydrogel formed an anisotropic morphology under a low static magnetic field (SMF) (30 mT) and showed conductive and mechanical features. Interestingly, under external electrical stimulation, the myoblasts cultured on the magnetic hydrogel exhibited oriented outgrowth. Arias et al. (2018) designed a magnetic bacterial cellulose (MBC) hydrogel by an in situ synthesis approach that mixed the dextran-coated Fe3O4 nanoparticles with bacterial cellulose pellicles.

The resulting MBC hydrogel could be activated with saturation magnetization and exhibited a moderate Young’s modulus (200−380 kPa), which was appropriate for vascular tissue engineering. Under an external magnetic field (0.3 T) stimulation, the produced gradient magnetic fields resulted in higher cell retention for the magnetically activated MBC hydrogel.

With the in situ precipitation method, numerous kinds of inorganic substances could be applied in the fabrication of the hydrogel networks, with good dispersion in the hydrogel matrix. Moreover, the synthesized approach is straightforward and economical. However, this method is only appropriate for limited hydrogels that possess stable networks. This is because the alkali solution used in the process might destroy the hydrogel network and limit the application of cell encapsulation (Wang et al., 2009).

The Grafting-Onto Method

In the grafting-onto methodology, there are covalent bonds formed between the magnetic particles and the hydrogel network. In detail, several functional groups are grafted onto the surface of the magnetic particles, which act as micro- or nanocrosslinkers to generate covalent bonds with the hydrogel monomers. Hu et al. (2019) designed a magnetic hydrogel made from non-toxic polyacrylamide (PAAm) hydrogel and 3-(trimethoxysilyl)propyl methacrylate coated Fe3O4 via the grafting-onto approach.

This novel magnetic hydrogel exhibited relatively high mechanical properties, including tensile strength and fracture toughness. In addition, polydimethylsiloxane (PDMS) was introduced to modify the surface of the magnetic hydrogel, and the resulting product exhibited excellent underwater performance. The PDMS-coated magnetic hydrogel kept stability even under fatigue loading, which highlighted significant potentials in the applications of artificial muscles.

Messing et al. (2011) firstly fabricated methacrylic groups functionalized magnetic CoFe2O4 nanoparticles. Then the magnetic hydrogels were fabricated by adding this kind of magnetic nanoparticles into a polyacrylamide hydrogel network.

An advantage of the grafting-onto approach is that the covalent bonds are capable of encapsulating the magnetic particles within the hydrogels, which promote the stability of the magnetic hydrogel. However, the long fabrication time, the high-cost protocol, and the complicated fabrication process restrict its broader applications in the biomedical field.

Applications In Bone Tissue Engineering

The repair of large bone defects caused by traumas, infections, cancers, or other diseases is still a thorny clinical problem (Herberg et al., 2019). Previous studies have shown that osteo-inductive growth factors played a significant role in bone regeneration (Cui L. et al., 2019; Ruehle et al., 2019) however, autologous bone graft remains the gold standard in the treatment of bone defects (Bouyer et al., 2016).

Considering the donor site morbidity and limited source of the donor area, the development of bone tissue engineering biomaterials is becoming more and more attractive for researchers. Most endeavors have been applied for the evaluation of MNPs-incorporated hydrogels in bone repair. As hydroxyapatite (HAP) is one of the most important components in natural bone inorganic substances, exhibits excellent biocompatibility and osteo-conductivity, and plays a key role in biomineralization (Moncion et al., 2019; Zhou et al., 2019), the magnetic HAP composite hydrogel was designed.

For example, nano-HAP coated γ-Fe2O3 nanoparticles (m-nHAP) were synthesized and then added into poly(vinyl alcohol) (PVA) solution to fabricate m-nHAP/PVA hydrogels. The PVA showed excellent biocompatibility, high mechanical properties, and slow biodegradation, which were crucial for its application (Iqbal et al., 2019; Venkataprasanna et al., 2019). The pore sizes of hydrogels rose gradually followed by the increased content of m-nHAP, which was accessible for nutrient exchange.

Meanwhile, the adhesion and proliferation of human osteoblasts were dramatically promoted as the m-nHAP concentration increased (Hou et al., 2013). However, the magnetic field was not introduced in this study, which might be considered as a potential promoter in improving bone tissue regeneration using this magnetic hydrogel.

Cells, such as stem cells, neural cells, and osteoblasts, are an important component in tissue engineering (Cerqueira et al., 2018; He et al., 2018; Ahmad et al., 2019; Chen M. et al., 2019; Midgley et al., 2019); therefore, MNP labeled cells are becoming more and more available in magnetically bioinspired hydrogels. Henstock et al. (2014) first added TREK1-MNPs or Arg-Gly-Asp (RGD)-MNPs into human mesenchymal stem cells (hMSCs) to fabricate MNP labeled cells, which were then seeded into either collagen hydrogels or poly(D, L-lactide-coglycolide) (PLGA) encapsulating bone morphogenetic protein-2 (BMP-2)-releasing collagen hydrogels (as shown in Figure 2A).

The RGD-binding sites of cell-surface mechanoreceptors (i.e., integrins) play an important role in transferring the external stimulus into the intracellular cytoskeleton (Cartmell et al., 2002). It was worth mentioning that hydrogels containing TREK1 or RGD-MNP labeled hMSCs showed significantly more mineralization than controls; moreover, hydrogels containing functionalized MNPs and BMP-2 had thicker and more numerous mineralized domains compared to those without BMP-2 (Figures 2B–K).

In order to maintain the stem cell phenotype and multiple differentiation potential ex vivo, a magnetic cell levitation method was used to label the MSCs with MNPs and then fabricated multicellular spheroids, which were implanted into type I collagen to form a magnetic hydrogel. Biological analyses showed that the 3D spheroid hydrogel system retained the functionality of MSCs, maintained the expression of stem cell markers, produced hematopoietic factors, and decreased cell-cycle progression genes, which could be able to establish an attractive platform for osteogenesis and drug delivery (Lewis et al., 2017).

The source article is very long. Read the rest here: ncbi.nlm.nih.gov

 

 

 

Edited by zarkov
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