24-May-2023: New artificial light-harvesting system using organic nanotubes useful for solar cells, photocatalysis, optical sensors & tunable multi-color light emitting materials
Inspired by natural photosynthetic systems, researchers have developed a new method of harvesting artificial light using organic nanotubes, which can be utilized in solar cells, photocatalysis, optical sensors, and tunable multi-color light-emitting materials.
In nature, plants and photosynthetic bacteria capture sunlight and deliver it to the reaction center through a cascade of energy and electron transfer steps for its eventual storage in the form of chemical energy. The antenna chromophores in the light-harvesting complexes are precisely aligned into arrays by the surrounding proteins, which in turn allows the energy migration between them in a highly efficient manner. Mimicking natural photosynthetic systems and understanding the fundamental processes of energy transfer has gained enormous interest in recent years, especially for systems that need energy conversion and storage.
Towards this direction, Dr. Supratim Banerjee from the Indian Institute of Science Education and Research (IISER) Kolkata, an autonomous Institute under the Ministry of Education, and Dr. Suman Chakrabarty from the S. N. Bose National Center for Basic Sciences (SNBNCBS), Kolkata, an autonomous institute of Department of Science and Technology (DST) carried out experimental and computational investigations on artificial light-harvesting in organic nanotubes derived from the union of an organic fluorescent molecule and a therapeutically important biopolymer. The former is an amphiphilic cationic molecule called cyano stilbenes (an organic molecule with fluorescent properties that are known to exhibit enhanced emission in their aggregated state), and the latter is an anionic therapeutically important bio-polymer called heparin (used as an anti-coagulant-during-surgery-and-in-post-operative-treatments) in aqueous media.
In the presence of heparin, the cationic cyano stilbenes employed in this study formed nanotubes with bright greenish-yellow emission through an electrostatically driven co-assembly process. Just like the antenna chromophores or pigmented (coloured) membrane-associated vesicles used to perform photosynthesis in bacteria, the nanotubes acted as highly efficient energy donors (antennae) in a system that mimicked the natural photosynthetic process.
They donated energy to acceptor dyes such as Nile Red and Nile Blue, resulting in emission color tuning from initial greenish-yellow to orange-red, including white light. The energy transfer phenomenon demonstrated in this study is known as FRET (Förster resonance energy transfer), which has significant importance in different applications such as the determination of DNA/RNA structures, mapping biological membranes, real-time PCR tests, and so on. The future is moving towards the conversion of solar energy for storage as chemical or electrical energy, and the process of energy transfer is a key factor for such applications.
In the study published in Chemical Science, the flagship journal of the Royal Society of Chemistry, the formation of the nanotubes was investigated by employing absorption and fluorescence spectroscopy, transmission electron microscopy (TEM), and fluorescence lifetime imaging microscopy (FLIM) studies. Molecular Dynamics (MD) simulation studies demonstrated that the cyano stilbene molecules formed cylindrical structures in the presence of heparin. The local molecular level interactions and packing of the cyano stilbene chromophores that led to the formation of one-dimensional nanostructures were also visualized and quantified through the simulation studies. Due to the temperature responsiveness of the FRET process in these systems, they were further employed as ratiometric emission thermometers (that sense temperature based on the variation in emission intensity at two different wavelengths) in the temperature range 20–90 °C, and this highlighted a practical application of these artificial light-harvesting systems.
3-May-2023: Smart gel-based sheet can form 3D Printed Conduit helping non-invasive nerve repair
A new smart gel-based sheet using three-dimensional (3D) printing technology that can self-roll into a tube during surgery to form a nerve conduit could help reduce the complexity of surgeries and aid rapid healing of nerve injuries.
The gold standard for the treatment of peripheral nerve injuries is still autografts. Bioresorbable polymer-based conduits are being explored for clinical use as alternatives. But these treatment strategies suffer from several limitations, such as donor site morbidity in the case of autografts and the necessity for sutures that demand highly skilled microsurgeries, and additional complications posed by sutures.
These clinical shortcomings motivated researchers at the Indian Institute of Science (IISc) in Bengaluru to design a smart gel-based sheet using three-dimensional (3D) printing technology that can self-roll into a tube during surgery to form a nerve conduit. In 3D printing, a virtual model of the part is created using design software, and the part is then fabricated using a 3D printer by layer-upon-layer deposition of the material. 3D printed parts can further undergo a shape change on demand upon activation after fabrication. Such technologies are now widely known as four-dimensional (4D) printing, where time is the extra dimension.
In a recent study, the team at IISc, led by Professor Kaushik Chatterjee, engineered a bilayered gel sheet by 3D printing in pre-defined patterns from two gels. The gel formulations were selected to swell differently. When the dried gel sheet was immersed in water, it rapidly swelled and curled into a tube. The folding behavior and final shape of the gel could be programmed to generate tubes of desired dimensions, which could be predicted by computational modeling. The gel sheets were then coated with thin nanometer-scale fibers to enable the body’s cells to adhere to the gel sheet.
The team at IISc worked closely with researchers at the Indian Institute of Technology at Roorkee and Maharishi Markandeshwar University to test the 4D printed conduits for repairing and regenerating a 2 mm gap in the sciatic nerve of rats. The shape-morphing sheets were placed under the defect region of the nerve and stimulated to wrap the defect site to form a conduit around the nerve without suturing. The nerve ends could grow through the implanted conduit. There was a remarkable improvement in nerve regeneration measured up to 45 days in the rats when the 4D printed nerve conduits were used. The team consisting of Akshat Joshi, Saswat Choudhury, Vageesh Singh Baghel, Souvik Ghosh, Sumeet Gupta, Debrupa Lahiri, G.K. Ananthasuresh, Kaushik Chatterjee reported its findings in a paper published in Advanced Healthcare Materials. This work was supported by the Science and Engineering Research Board (SERB), a statutory body of the Department of Science and Technology, under the Intensification of Research in High Priority Areas (IRHPA) special call on 3D Bioprinting.
Such 4D-printed parts have not been used in the clinic as yet. But such emerging technologies could pave the way for a new generation of medical devices that surgeons can deploy during surgery to heal nerves and many other tissues in coming years. They can offer benefits such as reduced complexity of surgeries, deployment by minimally-invasive procedures, and faster healing.
4-Mar-2023: World's first 200-meter-long Bamboo Crash Barrier “Bahu Balli” installed on the Vani-Warora Highway, Vidarbh, Maharashtra
An extraordinary accomplishment towards achieving Aatmanirbhar Bharat has been made with the development of the world's first 200-meter-long Bamboo Crash Barrier which has been installed on the Vani-Warora Highway, Vidarbh, Maharashtra.
This Bamboo Crash Barrier, which has been christened Bahu Balli, underwent rigorous testing at various government-run institutions such as the National Automotive Test Tracks (NATRAX) in Pithampur, Indore and was rated as Class 1 during the Fire Rating Test conducted at the Central Building Research Institute (CBRI) in Roorkee. Additionally, it has also been accredited by the Indian Road Congress. The recycling value of the bamboo barrier is 50-70% whereas that of steel barriers is 30-50%.
The bamboo species used in the making of this barrier is Bambusa Balcoa, which has been treated with creosote oil and coated with recycled High-Density Poly Ethylene (HDPE). This achievement is remarkable for the bamboo sector and India as a whole, as this crash barrier offers a perfect alternative to steel and addresses environmental concerns and their aftermath. Furthermore, it is a rural and agriculture-friendly industry in itself making it an even more significant milestone.