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Module 1: Nanotechnology and Shelf Life of Food Product

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Video 1: Sliding Filament Theory
Welcome back to the lecture series in application of nanomaterials in agriculture.So in the previous class we were discussing that how cerium oxide affects the musclesphysiology, cerium oxide nanoparticle.So, in that context I told you that there are interrogate physiology of the muscle onceyou understand that it will be very easy for you to appreciate that how this whole contractionprofile, force generation profile is being modulated by the presence of antioxidant nanomaterial.And apart from it I told you that will be talking about some of the tools micro fabricated,nano fabricated tools which are being use to understand muscle physiology and as a diagnostictools for muscle growth and muscle development and their respective force generation.So let us catch up where we left in the last class, in the last class if you remember,so this is where we were as we talked about the development of muscle.And there we talked about the alignment of the actin and the myosin filament as we couldsee.So, now today we will talk about these 2 aspects, sliding filament theory and excitation contractioncoupling apparatus and how cerium oxide is influencing it.So, when you look at a myo-tube cross-section of a myo-tube is something like this willbecomes myo-fibers.If I told you that there is a very interesting arrangement of the actin and the myosin filamentsso something like this.And if you go to any textbook referring to actin-myosin filament arrangement is skeletalmuscle, you will come across this kind of wonderfully drawn picture is I am not interestin the colors yet now soon I am going to do this.So, now you see there is a pattern here, so if I had to put the pattern say if it looksomething like this.So, I am translating these lines which I am making the red now, so these filaments whatyou see which I am now coloring them in red.These are the myosin filament and the myosin filament as I told you changes their proteinsubtypes as we mature.So some of them of thick, some of them are thin and depending on that they have a differentforce generation potential.And the one now I am putting them in green sorry blue these are the actin filaments whichare much more thinner.So now this is how this arrangement of myosin and actin is being orchestrated by nature.And the lines what I am drawing here the jagged lines these are the z lines and in betweenthese myo-tubes you will see some kind of gaps like this and then again another myotubes starts and this will continue.And we will talk later about those kind of jagged portions or the grooves which are formed,here you are having the actin filaments, here you are having the myosin filament.If you look at this picture pretty closely will observe something very neat, pictureis more like this.Here is a myosin, myosin has these kind of heads top of them, these are called the myosinheads, something like this and on top of that you are having this actin filaments rollinglike this.Now if you look at the actin filaments these are super molecular assemblies of multipleproteins something like this.And in the normal condition this actin filaments are in proximity with the myosin heads butthey are not in touch, they cannot interact with the actin filaments because of the blockageswhich are present out here, they something called these are different proteins presenton actin filament troponin-tropomyosin complex.There are multiple proteins which are involved in it that is not important.Now this troponin-tropomyosin complex it prevents the interaction of actin and myosin especiallythe myosin head and the actin filament, actin filament and myosin head.Now when there is a increase all of us sudden there is a increase of one of the cataionswhich is calcium Ca2+.This blockage between the myosin head and the actin because of the troponin and tropomyosincomplex is this complex gets disintegrated transiently.As soon as this complex troponin-tropomyosin complex gets disintegrated in the presenceof calcium ions, the myosin head binds to the actin filament here and it the somethingcalled a power stroke.So this head moves like this and when it moves like this there is a contraction which isobserved in the actin and the myosin filament.And this is where the force generation is, so the force with which this myosin head ismoving is what we call the muscle force all of them move like this, like this and thisis what generates the muscle.Now for this movement which is technically call as power stroke, you need ATP, now doesthis strike in the (()) (08:21).This is now to let us correlate what is happening when you talk about the presence of ATP there.And we are talking about the ATP content here, in the presence of cerium oxide redox couple.So, you realize in order for a process like this to occur you need to really appreciatehow 1 simple autocatalytic redox couple can change the muscle performance, so this iswhere this whole ATP thing comes.So, if you are more ATP then the power stroke is going to get will be able to enacts itis action better.And of course I will request you to go through the sliding filament theory which is justnow essentially I taught you and there is another which is called excitation contractioncoupling apparatus which is present somewhere out here in this zone which essentially regulatesthis calcium.Because this calcium cannot remain there forever, the calcium has to be dumb there and it hasto be pull back in a fraction of a movement and that is done by an organelle called sarcoplasmicreticulum.And one more thing what I want you to highlight here as you must have seen that these muscleshave higher power generation it means the mitochondria which is involve which is linedup this part all over those mitochondria are far more efficient in cerium oxide treatedanimals.So, this is the part what I wanted to highlight that a simple molecule can make a whole rangeof difference in the performance of muscle, with this brief idea about muscle biologyand the role of cerium oxide nanoparticle I will move on to a diagnostics aspects, aapproach by which you do not have to kill any animal or sacrifice any animal and yetyou can understand the muscle physiology better what are nanotechnology has to offer in termsof diagnostic tools.

Video 2: Nano and Micro Cantilevers
So, there will be talking about as we promised about nano and micro cantilevers it is.So, since now we have talked about the force generation out here or a stroke and the forcegeneration.So, we needed a tool to study force generation of the muscle of course you can do it invivoin animals as well as you can do it invitro.Invivo much of the tools unknown to the exercise physiologist, invitro there are upcoming toolswhich are using different kind of nano devices, micro devices to study in these kind of forcegeneration.So here I will talk about one such micro nano device which follows one of the techniqueswhat we discuss very early in the course how we can develop nanomaterial.You can develop nanomaterial from bottom of approach from top down approach.So, today we will talk about one of the micro nano device which is develop by top down approach.So, today we will talk about fabrication of micro and nano cantilevers for studying orfor diagnostics of muscle or it could be any kind of muscle.Fabrication of nano-micro depending on what size you are wait for the aspect ratio nano-microcantilever devices to study muscle force generation, muscle diagnostics.So, now what is really a cantilever, so all of you have must been at some point or otherinto swimming pool.We must have seen a swimming pool in television or internet or somewhere, say in a swimmingpool you must have seen that diving board.So, you have these diving boards where people kind of jump, so if you look at a diving boardthere is something like this, there is a plank dropping out like this.So, this is how the plank is been attached and this plank can move like this as wellas this, so the person stands here or maybe slightly closer here.The plank will be vibrating at a particular frequency right and of course you are havinga person which jumping in water over here and the plank is at a height.So essentially this is a classic situation of a cantilever, now this you have seen, nowthink of it if I could make such cantilevers in a micro dimension in order to measure forcesof nano newton, femtonewton and those kind of stuff.Now what does now this is from where you can understand the whole perspective, now I amreducing the size aspect ratio.Now what I will do I will take a block like this I am going on a top down approach, sayfor example I take a silicon wafer like this.It could be made on silicon, it could be made on PDMS poly dimethyl sulfoxide you guys canplease look at to these kind of compounds PDMS is I think it is a dow corning patentedcompound poly dimethyl sulfoxide silicon wafers if you take a wafer like this.Now what you do you have to have a mask, mask which will say what kind of shape you areasking.Say for example talking about the mask suppose I have a mask like this array of suppose Iwant an array of cantilevers like this.Now I am shading the part which are solid and the one which are not solid.So, now let me shade it fully that will kind of give you an idea how these kind of fabricationhappen.Now here I have a mask oh shit, now I want this pattern to be made on this block, whatI will do I will keep this mask.So, say for example I have this thin wafer of a certain thickness, now this also hasto be determined what will be the height from the base I want.So, the wafer what I am using a silicon wafer whatever I am using or a block whatever Iam using I have to decide what should be the thickness of it.Now what I will do I will keep the mask on top of it something like this I am puttingthe mask in black now and the wafer is underneath.Now using either a chemical technique or a laser base technique, lithography techniqueI am going to etch all those part where I am putting a red.I am going to heat away this part I am going to ensure by using certain chemicals or somethingI will leave the part which is in black line and all these par will be etched out.So, what have you obtaining is something like this exactly like this where I will have aarray of cantilevers sitting like this is the side view I am drawing.And of course the depth you have decided depending on the thickness of the block.This is precisely one of the top down approach by which micro cantilevers are being made.So, this kind of give you an idea when we talked pretty early the top down approachyou are breaking this stuff.You are kind of you know bringing down the size and all those things, now depending onthe size of the mask whatever is provided you can actually decide what dimension whataspect ratio of cantilever you are asking for you can go to the micron range, you caneven go down to nano range, you can go to even 100 meter, 100 nano meter range all upto you what kind of things you want to diagnose.In case of muscle general we go for a micron range, now how we do the diagnostics.Now after reaching to this point what you do, you allow the muscle cells to grow ontop of these cantilevers.In order for them to form myo-tubes and as I told you the myo-tubes are the smallestunit of muscle.So, once the myo-tube grows on top of it like this say for example you have the myo-tubesgoing like this.So, these myo-tubes will start generating force, so they will be contracting eitherin the presence of some drag or something or all by themselves at time.Once these myo-tubes will contract what will happen exactlythe same situation as I told you if this is a myo-tube sitting on top of it.This cantilever is going to vibrate at a certain frequency, now if you could make an arrangementsomething like this.Say for example I am just taking 1 cantilever into the picture for the diagnostic part purpose,say for example this is a myo-tube which is on top of the cantilever and this is the cantilever.Now this cantilever is vibrating at a particular frequency right, now from here underneathmake an arrangement to bounce a laser beam like this somewhere maybe here or here dependingon.You are bouncing a laser in this direction on the cantilever when there are no muscle,no myo-tube, that laser beam will bounce out from here.Now this angle what the laser beam is making with the cantilever is going to change.If a cantilever beam is going down based on that angle at the something called pleaselook into the literature on this Stoney’s equation.Stoney’s equation is almost 100 years old now or more than 100 years old, Stoney’sequation will help you to calculate the force what is being generated out there.So now if you know the force then depending on whatkind of drug molecule or what kind of pathological situation the muscle is or what kind of materialis working on muscle.We have a very simple tool by virtue of which you can quantify the force generated by themuscle.Now you see when you talk about diagnostics of using all kinds of nano tools.If you remember when you talk about all the applications out herediagnostic tools produced about force generation studies of muscle using micro/nano cantilever.So, these are some of the very interesting emerging tools which are coming very handyin the animal industry, if they are being used ina particular fashion.So, I will provide you the relevant literature which will kind of help you to appreciatethat these are already proven thing.And much of the invitro diagnostics are relying onthese kind of tools, so thisis I am going tocloseandwill move further inthis line with different kind of other tools where nanotechnology is coming pretty handyin the animal production, thank you.