Symposium SM04: Beyond Nano-Challenges and Opportunities in Drug Delivery

Anna Salvati, Groningen Research Institute of Pharmacy

Late News: Dissecting How Cells Internalize and Process Nano-Sized Drug Carriers for Nanomedicine Applications

Written by Jessalyn Hui Ying Low

For intracellular delivery of nanomedicines, nanomedicines have to first interact with the cell membrane and be recognized, after which they can be internalized by cells via a variety of cellular pathways. In this talk, Anna Salvati explains the research work done to understand deeper such interactions, in particularly how corona molecules can affect internalization of drugs. “By understanding these interactions better, we can design nanomedicines to achieve the desired outcomes at cell level and control these interactions,” says Salvati.

Salvati explains that when in a biological environment, formation of a corona occurs on the nanocarriers due to adsorption of surrounding biomolecules. This corona can in fact be recognized by cell receptors, mediating the interaction between the cells and nanoparticles. It was found that for the same nanoparticle, but with different corona compositions, the internalization pathway of the nanoparticle is also different, implying that different corona compositions are recognized differently by cell receptors. Salvati also highlights that even if a specific receptor is targeted, cells can internalize the nanoparticles via a different pathway as compared to the endogenous ligands. In addition, by changing the compositions of liposomes, it was shown how the corona composition can be tuned, and how this in turn affects the kinetics and mechanisms of uptake by the cell.

To understand better the mechanisms of internalization, it is also important to have better models beyond conventional in vitro cell cultures, as Salvati shares. One of such models the research group has developed are in vitro endothelial cell barriers, to mimic the barriers that nanomedicines face in vivo. It was found that when cells developed into a barrier, endocytic markers were expressed to different levels, and had a lower nanoparticle uptake as compared to standard cell cultures, indicating that such organization of the cells influences how nanoparticles are processed. Another model is a precision-cut tissue slices ex vivo model, where it was shown that precision-cut liver slices reproduced the preferential accumulation of nanoparticles by Kupffer cells as observed in vivo. This highlights how these models can be leveraged to better understand cellular internalization of nanomedicines occurring in vivo and optimize the design of nanomedicines.


Symposium SM09: Peptide and Protein Design for Responsive Materials

Minkyu Kim, University of Arizona

Late News: Artificial Protein Design Rules to Harness Protein Tertiary Structures for Polymeric Materials with Exotic Mechanical Behaviors

Written by Jessalyn Hui Ying Low

Erythrocytes carry oxygen throughout the body and are required to pass through narrow biological barriers like splenic slits. As such, they exhibit unique mechanical properties including reversible deformability and fatigue resistance, owing to the proteins found in their cytoskeleton, specifically ankyrin proteins. “If erythrocyte mimetic materials are available, that would be a breakthrough in drug delivery system fields for better biodistribution and long-term circulation of delivered pharmaceuticals, which cannot be achieved by most of current drug delivery systems,” says Minkyu Kim. In this talk, Kim shares how by designing polymer networks incorporated with protein structure, erythrocyte cytoskeleton mimicking materials can be built.

One of the key challenges in designing these polymer networks is the presence of topological defects such as molecular entanglements and loops, which could negatively affect mechanical properties. This is unlike in erythrocyte cytoskeleton, which have rod-like strands instead of coil-like strands. Therefore, by controlling strand rigidity, it is possible to reduce topological defects in the hydrogel’s polymer network.

When rod-like synthetic ankyrin protein strands were inserted into the hydrogel, it was found that the gel elastic modulus (G’) and gel relaxation time (λR) were close to tripled. This indicates the reduced topological defects in the network, likely due to the strain rigidity. This rigidity, however, also increased dangling chains, which could be decreased by inducing additional flexibility in the network. As such, flexible coil-like nonstructured protein strands were introduced, where strand flexibility could be controlled by rod:coil length ratio. It was found that at optimal rod:coil length ratio, λR was improved, implying that junction stability in the polymer network is enhanced, likely due to controlled mobility of the crosslinkers. Moreover, stability can be further improved when coupled with an asymmetric rod-coil protein design at the optimal rod:coil ratio, which may be due to reduced steric hindrance of rod-like proteins.  

Kim also reports that work is currently done to further develop these cytoskeleton-mimetic materials, in particular establishing selection criteria for crosslinkers such as crosslinking specificity and strength. With these design principles, it opens up new avenues for the development of soft materials with reduced network defects, with applications in tissue engineering and drug delivery systems.


Symposium EL02: Fundamentals of Halide Semiconductors for Optoelectronics

Ruth Shinar, Iowa State University

Tunable Perovskite-Based Photodetectors in Optical Sensing

Written by Victor A. Rodriguez-Toro

Compact spectroscopic platforms for (bio)chemical sensing have been proposed in the past. Typically, it consists of a light source in the visible range that sends an optical pulse to photoexcite a phosphorescent dye, which is embedded in a thin film like polystyrene (PS). Once the visible light is turned off (end of the optical pulse), a signal of photoluminescence (at longer wavelength than the light source) is emitted from the dye and sensed by a photodetector (PD). Characteristics of the emitted signal (amplitude and decay time) depend on the interaction of the dye with the analyte (e.g., oxygen) to detect. As the analyte concentration increases, the amplitude of the photoluminescence signal is lower, and the decay time is shorter. Therefore, two measurement modes to determine the analyte concentration can be established by monitoring (1) the optical intensity or (2) decay time. The latter constrains the response time of the light source and the PD to be in the order of 1 ms. Furthermore, it is desirable that the PD to have a low external quantum efficiency (EQE) at the wavelengths of the light source, but a high EQE at the wavelengths of the emitted signal of photoluminescence. 

Shinar and co-workers present the assessment of various photodetection technologies. First, inorganic PDs based on inorganic materials such as amorphous silicon are evaluated making evident their long response time (~250 ms) and the need for external filters. Second, organic photodetectors (OPDs) based on the polymer P3HT and the acceptor PCBM were evaluated showing low EQE in the region of interest for detection.

Finally, perovskite photodetectors (PPDs) were evaluated showing a high EQE, fast response times, and the ability to have systems with broadband and narrowband photodetection sensitivity.


Symposium NM03: Topological and Quantum Phenomena in Intermetallic Compounds and Heterostructures

Sahal Kaushik, Stony Brook University

Late News: Tunable Chiral Symmetry Breaking in Symmetric Weyl Materials

Written by Jessalyn Hui Ying Low

Asymmetric Weyl materials have an inherently chiral crystal structure, but lack symmetry between left- and right-handed fermions. Due to these properties, they exhibit many unique phenomena such as the quantized circular photogalvanic effect, yet are much rarer as compared to symmetric Weyl materials. In this talk, Sahal Kaushik shows how by applying external perturbations, in particular external magnetic field, chiral symmetry in symmetric Weyl materials can be broken to become asymmetric.

With a focus on materials with the -43m (Td) point group, Kaushik explains that for chiral symmetry breaking, it is insufficient to break only reflection symmetries as this could induce false chirality. Rather, all combinations of reflection and time reversal should be broken. Therefore, for a measure of true chirality, the magnitude of the magnetic field must be different along all three directions, implying that chirality will be broken when the magnetic field is applied along low symmetry directions like [147] and not high symmetry directions like [001] and [111]. It was shown that when magnetic field was applied along low symmetry directions, left- and right-handed Weyl cones indeed showed different energies, velocities, and tilts. These symmetry breaking parameters were influenced by magnitude and direction of the magnetic field. Notably, as the direction of magnetic field increased in asymmetry, the discrepancy between left- and right-handed Weyl cones increased, highlighting how chirality symmetry breaking in Weyl materials can be tuned.


Congratulations to the 2021 Virtual MRS Spring Meeting Science as Art Winners!

First Place


2021 Spring Meeting Graduate Student Awards

The MRS Graduate Student Awards are intended to honor and encourage graduate students whose academic achievements and current materials research display a high level of excellence and distinction. In addition to the MRS Graduate Student Gold and Silver Awards, the Arthur Nowick Graduate Student Award, which honors the late Dr. Arthur Nowick and his lifelong commitment to teaching and mentoring students in materials science, will be presented to a GSA finalist who shows particular promise as a future teacher and mentor.

Gold 

 

Chullhee Cho
Chullhee Cho

University of Illinois
at Urbana-Champaign

Ahyoung Kim
Ahyoung Kim
University of Illinois
at Urbana-Champaign

Joeson Wong
Joeson Wong
California Institute of Technology

Guomin Zhu
Guomin Zhu
University of Washington

 

Silver 

Jingshan S. Du
Jingshan S. Du
Northwestern University

Nikita Dutta
Nikita Dutta (Nowick Prize)
Princeton University

Zhiwei Fang
Zhiwei Fang
The University of Texas at Austin

Hanson Wang
Hansen Wang
Stanford University

 

Hanson Wang
Jiayue Wang
Massachusetts Institute of Technology

Wanghuai Xu
Wanghuai Xu
City University of Hong Kong

MRS acknowledges the generous contribution for the Nowick Award to the MRS Foundation from Joan Nowick in memory of her husband Dr. Arthur Nowick.


Best Poster Winners–2021 Virtual MRS Spring Meeting

Hector Mandujano, The University of Texas at El Paso, (CT04.01.06)

Changho Hon, Seoul National University, (CT05.14.05)    

Yunseul Kim, Gwangju Institute of Science and Technology, (EL01.10.15)

Daniel Davies, University of Illinois at Urbana-Champaign, (EL01.14.10)  

Jingjing Shi, Georgia Institute of Technology, (EL04.13.07)             

Wonjin Choi, University of Michigan–Ann Arbor, (EL05.13.03)     

Komalika Rani, Université Paris-Saclay, (EL09.07.01)        

Sang Seob Lee, Yonsei University, (EN01.08.05) 

Alessia Fortunati, Politecnico di Torino, (EN02.01.06)      

Virgil Andrei, University of Cambridge, University of Cambridge, (EN02.06.03)     

Eman Alhajji, King Abdullah University of Science and Technology, (EN03.08.01) 

Teresa Cristina Rojas, Instituto de Ciencia de Materiales de Sevilla, (EN05.03.04)

Davide Moia, Max Planck Institute for Solid State Research, (EN06.10.08)              

Eric Chang, Duke University, (EN07.04.04)            

Albanie Hendrickson-Stives, The Pennsylvania State University, (NM05.04.05)    

Hyoung Taek Kim, Sungkyunkwan University, (NM09.10.02)        

Chunhong Dong, Georgia State University, (SM01.03.03)               

Sebastian Buchmann, KTH Royal Institute of Technology, (SM03.01.06)  

Jeong Eun Park, Inha University, (SM05.06.05)   

Jisoo Jeon, Inha University, Inha University, (SM07.08.09)             

Che-Hsuan Cheng, University of Michigan–Ann Arbor, (ST01.07.07)          

Hojang Kim, Korea Advanced Institute of Science and Technology, (ST01.11.06)  

Kooknoh Yoon, Seoul National University, (ST04.04.07)


Symposium X: Frontiers of Materials Research

Symposium X—Frontiers of Materials Research_yi-cuiYi Cui, Stanford University
Nanotechnology for Sustainability

Written by Sophia Chen

Yi Cui of Stanford University delivered a Symposium X lecture on Thursday. A materials scientist, Cui discussed nanotechnology applications in sustainability efforts, such as reduction of fossil fuel use and pandemic mitigation efforts. Just in his lab alone, they use nanotechnology to design better batteries, medical face masks, and clothing.

One thrust of his group’s research is “trying to reinvent the battery,” said Cui. Over the last 15 years, Cui’s group has tackled questions such as how to improve the energy density of batteries, how to extend their lifetime, how to reuse and recycle them, all while making sure the technology is safe. He sees his work as the next generation to lithium ion batteries, now in widespread use in portable electronics and electric vehicles, and whose pioneers received the Nobel Prize in 2019.

Cui has developed new batteries from higher energy density materials by optimizing the geometry of the materials inside the batteries. For example, his group has made lithium-ion batteries with anodes made of silicon nanowires instead of the conventional graphite. However, silicon poses design challenges, as it expands several times its original size as the battery discharges. This can cause the silicon nanowires to crack and break, so Cui’s group has developed a shell-like structure around the silicon to avoid the material fracturing. They have also made strides in developing lithium metal batteries—a “holy grail” for the field because of the metal’s theoretical energy density. But in reality, lithium metal is challenging to work with because the metal expands dramatically and breaks easily. To prevent this, Cui’s group has developed hollow nano-capsules for lithium metal to sit in.

His group has also developed new techniques for imaging the dynamics inside batteries. In 2016, they developed the technique of cryogenic electron microscopy, which freezes material and images the material at atomic-scale resolution.

Nanofibers can also make high quality air filters, such as those needed in medical face masks, said Cui. His group has achieved filters with 60% porosity made from fibers 10 µm in diameter, spaced apart by 15 µm. This produces a breathable mask using a tiny amount of material.

Clothing that cools or heats the wearer could also make a significant difference in energy consumption, said Cui. His group has designed a polyethylene textile that is more transparent to the infrared radiation produced by the human body compared to cotton. In tests, they found the material caused the wearer’s skin temperature to be nearly 3°C cooler than when the person was wearing cotton. He pointed out that changing heating or cooling by a single degree Celsius can, on average, alter energy usage by 10 percent.

It’s important to get these innovations in the hands of consumers quickly, said Cui. His company Amprius, founded in 2009, has commercialized the silicon nanowire anode battery technology. He has recently founded the startup Eenotech for commercializing the polyethylene material, whose spinoff company LifeLabs Design will sell a limited quantity of clothing made from the polyethylene material this summer.

At the end of 2020, Cui became the director of Stanford’s Precourt Institute for Energy. As director, Cui oversees a range of research spanning many fields. In addition to materials and other hard science research, the institute weaves together researchers studying sustainable finance, policy, human behavior, artificial intelligence, and more.

Symposium X—Frontiers of Materials Research features lectures aimed at a broad audience to provide meeting attendees with an overview of leading-edge topics.


Bringing Perovskite Photovolatics to Consumer Market

Have you ever wondered about the bridge between fundamental scientific research and the consumer market? Or whether or not that solar cell you have been studying for a while would actually make it to the end user? The MRS EN06.09 session presents you with the latest on how to "Bring Perovskites to the Real World for a Smart Future".

One interesting presentation, in this session was the talk by Professor Kylie Catchpole, of Australian National University, presenting on "High Efficiency Perovskite/Silicon Solar Cells and Solar Hydrogen Systems". In her talk, professor Catchpole highlighted the recent increase in installation of photovoltaics in general compared to other electricity production technologies. "Solar and wind energy nowadays are cheaper than coal" emphasized Professor Catchpole, as she explained that the energy production market is mainly driven by cost. Photovoltaics also have the potential to be a low-cost source of hydrogen and other solar fuels. Higher efficiency of solar panels guarantees to lessen the overall cost of solar systems by reducing the number of modules needed. 

The achievement of a highly efficient solar cell is limited by charge recombination processes. Professor Catchpole and her research team used various passivation techniques to enhance the efficiency of their perovskites solar cells. Passivation is the addition of an insulating layer in between the interfaces of the perovskites to prevent charge recombination, as explained by professor Catchpole. In one technique they used an ultrathin (about 5 nm) passivation layer, composed of a mixture of PMMA and PCBM, to achieve high voltage and fill factor. In another technique, a nanostructured electron transport layer was passivated by the PMMA and PCBM mixture. Professor Catchpole’s team was able to achieve an efficiency “above 21% and fill factor of 83% for a 1 cm2 single junction perovskite cell” using this technique. The third passivation technique presented by Professor Catchpole utilizing two-dimensional (2D) perovskites resulted in the remarkable efficiency of 27.7%, for a 4-terminal tandem perovskite/silicon configuration. At the end, Professor Catchpole demonstrated how they used perovskite/silicon tandems in combination with an appropriate catalyst to construct a water splitting system of 17% efficiency. For more on this talk please click here

A simple fundamental understanding of an observation or a phenomena is a goal on its own. It also feels good to see that your work is being used in everyday life. That was my view on Wednesday's virtual MRS Spring Meeting and Exhibit. I will miss writing to you and learning with you as this is my last blog, for now ;) Tot Ziens!