Breaking News
September 26, 2018 - New insights into what drives organ transplant rejection
September 26, 2018 - Tiny Device Is a ‘Huge Advance’ for Treatment of Severe Heart Failure
September 26, 2018 - Research shows possibility to postpone cumbersome treatment for low-risk MDS patients
September 26, 2018 - CSU chemists may help in making extracorporeal life support devices more effective
September 26, 2018 - Blood-brain barrier can be important biomarker for early diagnosis of Alzheimer’s disease
September 26, 2018 - PCORI, AHRQ announce awards to support patient-centered outcomes research in learning health systems
September 26, 2018 - Scientists discover and characterize human skeletal stem cells
September 26, 2018 - Repeat CT Common in Peds Traumatic Epidural Hematoma
September 26, 2018 - Genetics Home Reference: bunion
September 26, 2018 - Increase observed in hearts from drug-intoxicated donors
September 26, 2018 - For Heart Failure Patients, Mitral Valve Procedure Improved Outcomes
September 26, 2018 - TINY cancer detection device shows promise as point-of-care detector of KSHV
September 26, 2018 - Women with non-small cell lung cancers live longer than their male counterparts
September 26, 2018 - KTU researchers engineer experimental bone to help treat osteoarthritis patients
September 26, 2018 - Foundation for a Smoke-Free World calls for proposals to implement Smoke-Free Index
September 26, 2018 - Functional Imagery Training helps lose five times more weight than talking therapy
September 26, 2018 - Fewer American Teens Having Sex, Most Using Birth Control
September 26, 2018 - We are predisposed to forgive, new research suggests
September 26, 2018 - Insomnia Exacts Heavy Toll on Quality of Life
September 26, 2018 - Clinical study shows efficacy, safety of novel drug-eluting stent with improved radiographic visibility
September 26, 2018 - Cytox, AIBL announce expanded agreement to assess genetic risk for Alzheimer’s
September 26, 2018 - Study finds persistent rate of lawnmower injury-related emergency department visits
September 26, 2018 - Researchers find molecule that halts, reverts neurodegeneration caused by Parkinson’s disease
September 26, 2018 - Novartis announces winners of 2018 eXcellence in Ophthalmology Vision Award
September 26, 2018 - New spinout company to tackle drug-resistant infections with novel antibiotics
September 26, 2018 - In depression the brain region for stress control is larger
September 26, 2018 - Smuggling RNA into cells can activate the immune system to fight cancer
September 26, 2018 - Special Focus Issue takes wide view of complementary and integrative medicine in cancer
September 26, 2018 - Researchers now confirm that genome duplication drives evolution of species
September 25, 2018 - Study provides evidence of beta lactamase producing, antimicrobial resistant E. coli in U.S. retail meat
September 25, 2018 - UCI study finds new cause of cerebral microbleeds
September 25, 2018 - Researchers propose mechanism by which ASTN2 protein defects lead to brain disorders
September 25, 2018 - Chinese and German researchers to cooperate more closely in future for better food
September 25, 2018 - Recent study helps predict probability of pregnant mothers to have child with autism
September 25, 2018 - New online, sound matching tool offers tinnitus sufferers potential treatment options
September 25, 2018 - UC Davis researchers take critical step in developing more effective Salmonella vaccine
September 25, 2018 - Antibiotics best paediatric treatment for children’s chronic wet cough
September 25, 2018 - Looking beyond opioids: Stanford pain psychologist briefs Congress
September 25, 2018 - Organs actively fighting back against autoimmune diseases, finds study
September 25, 2018 - Lancaster professor aims to understand how genes affect smoking cessation
September 25, 2018 - Human-oriented perspective needed to better understand Parkinson’s disease
September 25, 2018 - Physical activity may have beneficial effects for people with rare Alzheimer’s disease
September 25, 2018 - FDA Updates on Valsartan Recalls
September 25, 2018 - 3-D-printed tracheal splints used in groundbreaking pediatric surgery
September 25, 2018 - Who is the designated driver, or proxy, for your health decisions?
September 25, 2018 - New chemo-optogenetic method enables multi-directional activity control of cellular processes
September 25, 2018 - Study explores link between genetic predisposition to Alzheimer’s and cardiometabolic risk factors
September 25, 2018 - NeoTract presents new clinical data from studies of UroLift System for patients with BPH
September 25, 2018 - Patients with paralysis manage to walk thanks to new technology
September 25, 2018 - Statins Improve Long-Term Survival After AAA Repair
September 25, 2018 - Novel brain network linked to chronic pain in Parkinson’s disease
September 25, 2018 - Researchers reassess negative pressure wound therapy as its benefit and harm remain unclear
September 25, 2018 - Older adults with ‘fall plan of care’ less likely to suffer fall-related hospitalizations
September 25, 2018 - FDA lifts partial clinical hold that paused enrollment of new patients in tazemetosta clinical trials
September 25, 2018 - IME Medical Electrospinning establishes state-of-the-art manufacturing lab facilities
September 25, 2018 - Phase 1 and 2 clinical trials of entrectinib drug in ROS1-positive NSCLC show promising results
September 25, 2018 - How to Protect Your Eyesight
September 25, 2018 - Novel approach allows researchers to define how cells in the retina respond to diabetes
September 25, 2018 - Columbia University announces winners of 2018 Louisa Gross Horwitz Prize
September 25, 2018 - New model enables anyone to run powerful simulations, complex calculations easily
September 25, 2018 - Clinical trial investigators found non-compliant with requirement to report results on EU register
September 25, 2018 - Study analyzes quality of protein supplements in function of source, treatment and storage
September 25, 2018 - FDA grants Orphan Drug Designation to Myelo001 for treatment of Acute Radiation Syndrome
September 25, 2018 - U.S. Alzheimer’s Cases to Nearly Triple by 2060
September 25, 2018 - Improving cell replacement therapy for Parkinson’s disease
September 25, 2018 - Genervon reports new findings that drug candidate GM6 attenuates Alzheimer’s disease in mice model
September 25, 2018 - FDA approves new 5 mm diameter drug-eluting stent from Cook Medical
September 25, 2018 - New $17.8 million grant ensures USC at forefront of research on tobacco-related health risks
September 25, 2018 - Researchers analyze response to combination immunotherapy for patients with rare skin cancer
September 25, 2018 - Study sheds light on how brain protein may be involved neurodevelopmental disorders
September 25, 2018 - Where to draw the line on incentives
September 25, 2018 - Solid fuel use linked with increased risk of hospitalization or death from respiratory diseases
September 25, 2018 - ‘Trouble Brewing’ report highlights steps that governments can take to reduce alcohol-related harms
September 25, 2018 - Recurrence risk of VTE appears similar for patients with cancer and those with unprovoked VTE
September 25, 2018 - Global leaders must make bold commitments at first-ever UN tuberculosis summit
September 25, 2018 - Brief sleep intervention works long-term to prevent child obesity
September 25, 2018 - Vaping among kids and teens a growing concern
September 25, 2018 - Public launch of products and application solutions from Porvair Laboratory Division
September 25, 2018 - Harmful H. pylori may play a role in Parkinson’s disease
September 25, 2018 - Researchers develop way to measure different types of fear of falling in patients with Parkinson’s
Studying the nanomechanical properties of aging and cancerous cells using AFM

Studying the nanomechanical properties of aging and cancerous cells using AFM

image_pdfDownload PDFimage_print

An interview with Prof. Igor Sokolov, Tufts University conducted by April Cashin-Garbutt, MA (Cantab)

Can you please explain how you use AFM to study the nanomechanical properties of cells related to aging processes and cancer?

Force microscopy is a technique which would probably be best described with the help of a small finger with an apex just a few atoms in size that can touch objects. This is a learning finger.

It is exactly like when we learn things about the world around us using our fingers. You can touch, push and scratch; you can see how much your finger sticks to objects. Biological cells are an example of these objects. We study physical characterisics of cells using this learning finger, the AFM probe. We look at aging and cancer because these are probably the most interesting and challenging topics.

Aging is something beyond our imagination because, even if you think about some of the craziest science fiction, there is literally no description of a future for humans with immortality, because, people do not know how to handle this.

For example it is an open question whether aging is pre-programmed. We do not know that. There is a lot of biochemical theories definng what aging is. Biology is essentially biochemistry. These days we can study physics of objects, particularly on a small scale such as the cellular level cells. To do that, you need something like a finger, AFM probe because it provides a physical touch, a must to study physical information.

As you do that, you learn first the mechanics of cells − how responsive they are to external loads, pressure, scratching, and even tickling. As almost a joke, we came across an interesting phenomenon. When we started to poke cancer and normal cells (human cervical epithelial cells) with a sharp AFM probe, the cancer cells started to crawl away, whereas normal cells remain still.

Credit: royaltystockphoto.com/Shutterstock.com

If you use a dull probe or sphere, both cell types were okay. It is almost like the cancer cells don’t like tickling or something like that. This is an observation we have not published. We still do not know why they behaved like that. This is just an example of how many things we don’t know about the physics of cancer.

It is also not known what cancer is, whether it is a switch or a mutation, as generally believed. From a physical point of view, it is literally unknown and I think force microscopy is the only technique capable of enabling the comprehensive study of cells, including the mechanics of the cell body and physical properties of layers  surrounding cells.

What new modes have you developed to use AFM to study mechanical properties of both living cells and materials/polymers?

One mode is called FT-nanoDMA. FT stands for the Fourier Transform. There are different ways you can measure cell mechanics, but one of them is very natural; you push a cell and start to vibrate your probe a little bit with different frequencies, and then you measure the response.

Usually, it is done sequentially. You vibrate at one frequency, then at another frequency, and another and so on. It takes time. But cells are alive, it is not very measurement-friendly because it keeps changing.

What we did was simply send all these vibration frequencies altogether at once. It resulted in rather fast measurements. The area of contact between the AFM probe and sample stays almost the same, which is paramount for qantititative measurements. Our estimations show that the speed of measurements has increased almost two orders of magnitude.

It is a similar improvement with the spatial resolution; we found almost a hundred times increase inresolution. A hundred times higher resolution is a fairly big difference; it is the difference between optical and electron microscopy, for example.

We published this just over a year ago. Practical implementation requires some additional hardware to exisiting AFMs. Right now it is commercialized by NanoScience Solutions, Inc.

Now, just literally two days ago, I received notice of acceptance of our other paper describing another AFM mode. When you disconnect an AFM probe (your learning finger) from a sample surface, you usually pull up some molecules and a little bit of surface itself. All that information is there.

However, previously, that information was filtered out because it was treated as noise in the existing sub-resonant tapping modes. What we did was process that information before it was filtered out. It required to attach some new faster electronics to the existing AFM. So it has been done on Bruker AFMs, but it should work on all AFM, even old ones. The results are much better than we expected.

We can record up to eight new channels of information, much faster and with less artefacts compared to the existing sub-resonant tapping modes. This mode has been also already commercialized by NanoScience Solutions, Inc.

This is a really new and promising mode. We are currently applying this for cancer detection, together with medical collaborators.

What were the main challenges you had to overcome?

We have had to face both technical and societal/psychological challenges. Regarding the technical challenges, atomic force microscopy is a fairly young technique. Although it is almost 30 years old, it has passed through the same stages that all new techniques.

In the beginning, there was a lot of excitement, abuse of the technique, and bursting of this bubble of initial interest. Now it has slowly started to become generally accepted method. Still, it requires a lot of learning, and that is where students have to be prepared. Getting just a picture with AFM is not a big deal; it simply records force interaction between an AFM probe and sample surface.

However, if you don’t know which force it could be, then you may get some artefacts and incorrect results. That is the biggest difficulty. AFM it is not just a push-button technique. You have to interpret the obtained image. Of course, sometimes there are some simple cases, but if you are really at the frontiers with this technique, that’s the difficulty.

The second difficulty relates to research and education. It is interesting how the education and research are going together. Both keep changing. It was different literally five or ten years ago. In the United States, if you are in a tenure-track position, you have to fight for money. You have to write grant applications and papers. It is very hard to find time to learn something deep and new, to go to the lab to do it yourself.

Therefore, you typically rely heavily on students. But they have their own agenda, which is to get a PhD. If they see a new or more complicated approach compared to what traditionally published, they try to get around it to get faster results. If the professor insists, they may say “I tried and it did not work well”, and then they use the simpler approach while professors simply don’t have time to do that themselves.

That is why the popular approach is the simplest one. This is the problem of AFM because it captures so much complexity – you literally get direct information from interactions, even atomic interactions in the nanoscale. You get gigabytes of data. If you really want to process all those data it requires a lot of knowledge and interpretation of what is being observed.This is what I think is slowing down general acceptance of this technique.

How can this be overcome?

I think it is simply psychological. Some people will realize that to get something good with this technique you need to invest a little bit more time. On the other hand, the technology keeps developing and becomes more user-friendly.

Right now, I can compare several new AFMs by Bruker, for example, with automatic car transmission. You do not need to have the knowledge of driving a standard car. Many people like it. It feels faster to learn. Personally, I like some tweaks, but at the same time, I hate driving a non-automatic car.

I think that with time, people will definitely get a truly user-friendly AFM. However, the physics and need in knowledge of forces at the nanoscale are still there, and will always be there. You need to really learn and understand what is measured and that is still a difficulty.

Can you please outline how you are studying viscoelastic properties using the nanoDMA?

You simply push a surface with a predefine force to develop some area of contact, and then, you oscillate the probe with several frequencies altogether. Right now, we work with ten frequencies, which is sufficient for many applications.

We can do more. It is still about balancing the cost of the hardware and how many frequencies you need analyze at the same time. This frequency-based method  is the most model-independent one to characterize materials, particularly soft materials like cells.

The range of frequencies is currently from single Hz up ~500 Hz. The maximum frequency is defined by the previous study of  polymers. For polymers, there is a large database of information of their viscoelastic properties up to 300 Hz, which has the gold standard. There is some indication that it might be interesting to go to very high frequencies. There are other people doing research in high frequency viscoelastic measurements, but I think low frequency is important, in particular for biology. It is important for cells, for example, because they are soft and they don’t like being shaken at mega-Hertz frequencies.

How has AFM directly advanced or helped your research?

AFM can measure not only mechanics and physical interactions, but it can measure electrical properties, tribology, and measure how durable the surface is, etc.

AFM, which is the same as scanning probe microscopy, is a family of different techniques. Although we use quite a lot of techniques, I don’t know of any other technique capable of getting such a large amount of various information about surfaces. I would say it is my favorite technique, although we are using many different ones to study the self-assembly of molecules on the surface and the properties of cells and tissues.

I recently started to study organoids, a completely different approach that is very popular these days. This is because, when you look at a tumor, for example, it is not even clear which cells are cancer cells and, which are not. This became almost impossible to identify at the single cell level. If you look at cells in a Petri dish (in vitro), they are separated in 2 dimensions on solid substrate. It may have a very little relation to real organs.

Nowadays what people do, they have started to build a kind of embryo/seed of organs using well-defined cells. This seed is called call organoid. All of the cells are known. The genetic make-up is known. You know which cells are normal and which ones are cancerous. This is a bridge between the two worlds of in vivo and in vitro.

What is the importance of meetings, like the AFM BioMed Conference, to you and the AFM research community?

It is very important because professors are busy, and with all the papers to read, it is very hard to get a good perception of the frontiers and what is going on in the community.

People do not publish negative results, but at conferences, you can at least mention it. From the learning point of view, negative results may be more educational than positive. Also, you can ask questions directly, which is very important.

Finally, such meetings are the place where you can convince people that it is worth looking at a particular approach. Maybe it is difficult, but it is worth it. Since such meetings involve professors and students, the professors have an additional motivation to push students to investigate more deeply. Of course, personal relations are important to us all, it also fuels collaborations.

Online meetings are fine for ongoing collaborations, but if you are thinking about something new, you need personal meetings. Furthermore, it is very important for students. Sometimes, students are very close with the collaborators such as their professors and their peers, but when they start seeing the world it typically motivats them a lot. Thus, such meetings are very important for them.

Conferences are very important in general, but particularly for force microscopy in biomedical applications. The biomedical arena has been number one on the horizon of force microscopy right after it was created. Yet therewere so many difficulties that up to now there is literally no medical application of atomic force microscopy.

I think it is extremely important to orginize such conferences because we are trying to help to give birth to this area of medical applications. I am trying to work with doctors and I see how difficult it is. It is not only about different vocabularies, it is a different universe, different paradigm and different goals..

To effectively communicate the great benefits of using AFM in medical area, we need to define a topic which may be  particularly interesting for medicine. This type of conferences is a great place to discuss these topics, and may be to endorse it by the AFM community.

What direction do you see, or would like to see, AFM going in the next five years? What do you see as the next big thing for AFM?

There will probably be faster electronics, more sophisticated algorithms, and more user-friendly interfaces. Increased speed is one of the most interesting parts of the discussion − whether force microscopy will be as fast as real-time video? I think it will, but it would have limited applications , not for all samples.

Secondly, control of the AFM probe is also very important. The probe that touches the surface is typically controlled through a feedback. For example, the load forceacting  between the probe and surface is kept constant during scanning by a feedback system.. At present, control feedback system is rather basic  compared to what is used in the communities dealing with feedback controls.                       

It is definitely time for the control system to be more sophisticated. As a result, the speed of force microscopy would increase enormously, and at the same time, it will preserve the sample. I think there will be new controls implemented in future AFMs.

Where can readers find more information?

About Prof. Igor Sokolov

Igor Sokolov received his B.S. in Physics from St. Petersburg State University, Russia in 1984, and earned his Ph.D. from D.I. Mendeleev Central Institute for Metrology the Soviet Bureau of Standards (Russian NIST), Russia in 1991. In 1992, he was the recipient of the E.L. Ginzton International Fellowship Award from Stanford University for his work on atomic force microscopy.

Igor worked as a research associate in the University of Toronto’s Physics and Chemistry Departments before moving to Clarkson University in 2000 to join their Physics Department, where he achieved the title of full professor and served as director of the Nanoengineering and Biotechnology Laboratories Center. Now he is Professor at Tufts University and Bernard M. Gordon Senior Faculty Fellow. During his career, he has consulted for many large corporations such as Proctor and Gamble, General Electric, Arkema Group, Inc. and Purdue Pharma.

He has 150+ refereed publications, including such journals as Nature, Nature Nanotechnology, Nature Methods, Advanced Materials, etc.. He holds 20 patents (issued and pending). Igor’s current research focuses on nanomechanics of soft material, molecules and cells; atomic force microscopy; nanophotonics, and the studies towards understanding of nature of cancer, early detection of cancer based on altered biophysical properties; self-assembly.

Tagged with:

About author

Related Articles