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1. Giant conductance of PSS:PEDOT micro-surfaces induced by microbubble lithography

Author

Ranjan, Anand Dev, Sen, Rakesh, Kumar, Sumeet, Vaippully, Rahul, Dutta, Soumya, Roy, Soumyajit, Roy, Basudev, and Banerjee, Ayan

Subjects
Physics - Chemical Physics, Condensed Matter - Materials Science
Abstract

We provide direct evidence of the effects of interface engineering of various substrates by Microbubble lithography (MBL). We choose a model organic plastic (or polymer) poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), with conductivity of 140 S/cm, as a representative organic system to showcase our technique. Thus, we fabricate permanent patterns of PEDOT:PSS on glass, followed by a flexible PDMS substrate, and observe conductivity enhancement of 5 times on the former (694 S/cm), and 20 times (2844 S/cm) on the latter, without the use of external doping agents or invasive chemical treatment. Probing the patterned interface, we observe that MBL is able to tune the conformational states of PEDOT:PSS from coils in the pristine form, to extended coils on glass, and almost linear structures in PDMS due to its more malleable liquid-like interface. This results in higher ordering and vanishing grain boundaries leading to the highest conductivity of PEDOT:PSS on PDMS substrates.

Published
2023

2. Roadmap for optical tweezers

Author

Volpe, Giovanni, Maragò, Onofrio M, Rubinsztein-Dunlop, Halina, Pesce, Giuseppe, Stilgoe, Alexander B, Volpe, Giorgio, Tkachenko, Georgiy, Truong, Viet Giang, Chormaic, Síle Nic, Kalantarifard, Fatemeh, Elahi, Parviz, Käll, Mikael, Callegari, Agnese, Marqués, Manuel I, Neves, Antonio AR, Moreira, Wendel L, Fontes, Adriana, Cesar, Carlos L, Saija, Rosalba, Saidi, Abir, Beck, Paul, Eismann, Jörg S, Banzer, Peter, Fernandes, Thales FD, Pedaci, Francesco, Bowen, Warwick P, Vaippully, Rahul, Lokesh, Muruga, Roy, Basudev, Thalhammer-Thurner, Gregor, Ritsch-Marte, Monika, García, Laura Pérez, Arzola, Alejandro V, Castillo, Isaac Pérez, Argun, Aykut, Muenker, Till M, Vos, Bart E, Betz, Timo, Cristiani, Ilaria, Minzioni, Paolo, Reece, Peter J, Wang, Fan, McGloin, David, Ndukaife, Justus C, Quidant, Romain, Roberts, Reece P, Laplane, Cyril, Volz, Thomas, Gordon, Reuven, Hanstorp, Dag, Marmolejo, Javier Tello, Bruce, Graham D, Dholakia, Kishan, Li, Tongcang, Brzobohatý, Oto, Simpson, Stephen H, Zemánek, Pavel, Ritort, Felix, Roichman, Yael, Bobkova, Valeriia, Wittkowski, Raphael, Denz, Cornelia, Kumar, GV Pavan, Foti, Antonino, Donato, Maria Grazia, Gucciardi, Pietro G, Gardini, Lucia, Bianchi, Giulio, Kashchuk, Anatolii V, Capitanio, Marco, Paterson, Lynn, Jones, Philip H, Berg-Sørensen, Kirstine, Barooji, Younes F, Oddershede, Lene B, Pouladian, Pegah, Preece, Daryl, Adiels, Caroline Beck, De Luca, Anna Chiara, Magazzù, Alessandro, Ciriza, David Bronte, Iatì, Maria Antonia, and Swartzlander, Grover A

Subjects
Physical Sciences, Classical Physics, Nanotechnology, Bioengineering, optical tweezers, optical trapping, optical manipulation, Atomic, molecular and optical physics, Quantum physics
Abstract

Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.

Published
2023

3. Roadmap for Optical Tweezers

Author

Volpe, Giovanni, Maragò, Onofrio M., Rubinzstein-Dunlop, Halina, Pesce, Giuseppe, Stilgoe, Alexander B., Volpe, Giorgio, Tkachenko, Georgiy, Truong, Viet Giang, Chormaic, Síle Nic, Kalantarifard, Fatemeh, Elahi, Parviz, Käll, Mikael, Callegari, Agnese, Marqués, Manuel I., Neves, Antonio A. R., Moreira, Wendel L., Fontes, Adriana, Cesar, Carlos L., Saija, Rosalba, Saidi, Abir, Beck, Paul, Eismann, Jörg S., Banzer, Peter, Fernandes, Thales F. D., Pedaci, Francesco, Bowen, Warwick P, Vaippully, Rahul, Lokesh, Muruga, Roy, Basudev, Thalhammer, Gregor, Ritsch-Marte, Monika, García, Laura Pérez, Arzola, Alejandro V., Castillo, Isaac Pérez, Argun, Aykut, Muenker, Till M., Vos, Bart E., Betz, Timo, Cristiani, Ilaria, Minzioni, Paolo, Reece, Peter J., Wang, Fan, McGloin, David, Ndukaife, Justus C., Quidant, Romain, Roberts, Reece P., Laplane, Cyril, Volz, Thomas, Gordon, Reuven, Hanstorp, Dag, Marmolejo, Javier Tello, Bruce, Graham D., Dholakia, Kishan, Li, Tongcang, Brzobohatý, Oto, Simpson, Stephen H., Zemánek, Pavel, Ritort, Felix, Roichman, Yael, Bobkova, Valeriia, Wittkowski, Raphael, Denz, Cornelia, Kumar, G. V. Pavan, Foti, Antonino, Donato, Maria Grazia, Gucciardi, Pietro G., Gardini, L., Bianchi, G., Kashchuk, A., Capitanio, M., Paterson, Lynn, Jones, P. H., Berg-Sørensen, Kirstine, Barooji, Younes F., Oddershede, Lene B., Pouladian, Pegah, Preece, Daryl, Adiels, Caroline Beck, De Luca, Anna Chiara, Magazzù, A., Ciriza, D. Bronte, Iatì, M. A., and Swartzlander, Grover A.

Subjects
Physics - Optics, Condensed Matter - Soft Condensed Matter
Abstract

Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nanoparticle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration., Comment: 181 pages, 61 figures

Published
2022

4. Simultaneous optical trapping and magnetic micromanipulation of ferromagnetic iron-doped upconversion microparticles in six degrees of freedom

Author

Nalupurackal, Gokul, M, Gunaseelan, Lokesh, Muruga, Vaippully, Rahul, Chauhan, Amit, Nanda, B. R. K., Sudakar, Chandran, Kotamarthi, Hema Chandra, Jannasch, Anita, Schffer, Erik, Senthilselvan, Jayaraman, and Roy, Basudev

Subjects
Physics - Optics, Physics - Applied Physics, Physics - Medical Physics
Abstract

Optical trapping of magnetic Fe-oxide particles is notoriously difficult due to their high refractive indices, not to mention high absorptivity at the trapping infra-red wavelengths. We synthesize Fe co-doped NaYF4:Yb,Er ferromagnetic upconversion particles that not only have refractive indices conducive for optical trapping, but also heat less than Haematite particles at off-resonant wavelengths. These particles are hexagonal shaped with dimensions of the order of 3 micrometer and also bear high coercivity of 20 mT and saturation magnetisation of 1 Am^2/kg. This enables simultaneous use of optical trapping and magnetic forces to generate micro-manipulation in all the six degrees of freedom of a rigid body. We also show that these particles heat significantly when illuminated on absorption resonance at 975 nm while emitting visible light with possible implications for fluorescence microscopy and photothermal therapy of cancer cells., Comment: 18 pages, 10 figures

Published
2022

5. Detection of sub-degree fluctuations of the local cellmembrane slope using optical tweezers

Author

Vaippully, Rahul, Ramanujan, Vaibavi, Gopalakrishnan, Manoj, Bajpai, Saumendra, and Roy, Basudev

Subjects
Physics - Biological Physics, Condensed Matter - Soft Condensed Matter, Physics - Optics
Abstract

Normal thermal fluctuations of the cell membrane have been studied extensively using high resolution microscopy and focused light, particularly at the peripheral regions of a cell. We use a single probe particle attached non-specifically to the cell-membrane to determine that the power spectral density is proportional to (frequency)^(-1.66) in the range of 5 Hz to 1 kHz. We also use a new technique to simultaneously ascertain the slope fluctuations of the membrane by relying upon the determination of pitch motion of the birefringent probe particle trapped in linearly polarized optical tweezers. In the process, we also develop the technique to identify pitch rotation to a high resolu-tion using optical tweezers. We find that the power spectrum of slope fluctuations is proportional to 1/(frequency), which we also explain theoretically. We find that we can extract parameters like bending rigidity directly from the coefficient of the power spectrum particularly at high frequencies,instead of being convoluted with other parameters, thereby improving the accuracy of estimation.We anticipate this technique for determination of the pitch angle in spherical particles to high resolution as a starting point for many interesting studies using the optical tweezers

Published
2020

6. Pitch-rotational manipulation of single cells and particles using single-beam thermo-optical tweezers

Author

Kumar, Sumeet, Gunaseelan, M., Vaippully, Rahul, Kumar, Amrendra, Ajith, Mithun, Vaidya, Gaurav, Dutta, Soumya, and Roy, Basudev

Subjects
Condensed Matter - Soft Condensed Matter, Physics - Optics
Abstract

3D pitch rotation of microparticles and cells assumes importance in a wide variety of applications in biology, physics, chemistry and medicine. Applications such as cell imaging and injection benefit from pitch-rotational manipulation. Generation of such motion in single beam optical tweezers has remained elusive due to complicacies of generating high enough ellipticity perpendicular to the direction of propagation. Further, trapping an extended object at two locations can only generate partial pitch motion by moving one of the foci in the axial direction. Here, we use hexagonal-shaped upconverting particles and single cells trapped close to a gold-coated glass cover slip in a sample chamber to generate complete 360 degree and continuous pitch motion even with a single optical tweezers beam. The tweezers beam passing through the gold surface is partially absorbed and generates a hot-spot to produce circulatory convective flows in the vicinity which rotates the objects. The rotation rate can be controlled by the intensity of the laser light and the thickness of the gold layer. Thus such a simple configuration can turn the particle in the pitch sense. The circulatory flows in this technique have a diameter of about 5 $\mu$m which is smaller than those reported using acousto-fluidic techniques.

Published
2020

7. In-vivo characterization of optically trapped Brownianprobes at a glance

Author

Vaippully, Rahul, Ramanujan, Vaibavi, Bajpai, Saumendra, and Roy, Basudev

Subjects
Physics - Biological Physics, Physics - Fluid Dynamics, Physics - Optics
Abstract

Calibration of optically trapped particles in-vivo has been complicated given the frequency dependence and spatial inhomogeneity of the cytoplasmic viscosity, and the requirement of accurate knowledge of the medium refractive index. Further, it has been demonstrated that the medium viscosity is dependent upon the measurement probe leading to reliability issues for measurements with even micrometer sized particles. Here, we employ a recent extension of Jeffery's model of viscoelasticity in the microscopic domain to fit the passive motional power spectra of micrometer-sized optically trapped particles embedded in a viscoelastic medium. We find excellent agreement between the 0 Hz viscosity in MCF7 cells and the typical values of viscosity in literature, between 2 to 16 mPa sec expected for the typical concentration of proteins inside the cytoplasmic solvent. This bypasses the dependence on probe size by relying upon small thermal displacements. Our measurements of the relaxation time also match values reported with magnetic tweezers, at about 0.1 sec. Finally, we calibrate the optical tweezers and demonstrate the efficacy of the technique to the study of in-vivo translational motion.

Published
2019

8. Detection of self-generated nanowaves on the interface of an evaporating sessile water droplet

Author

Bhatt, Dhanush, Vaippully, Rahul, Kharbanda, Bhavesh, Ranjan, Anand Dev, R., Sulochana, Dharod, Viraj, and Roy, Basudev

Subjects
Physics - Optics
Abstract

Evaporating sessile droplets have been known to exhibit oscillations on the air-liquid interface. These are generally over millimeter scales. Using a novel approach, we are able to measure surface height changes of 500 nm amplitude using optical trapping of a set of microscopic particles at the interface, particularly when the vertical thickness of the droplet reduces to less than 50 $\mu$m. We find that at the later stages of the droplet evaporation, particularly when the convection currents become large, the top air-water interface starts to spontaneously oscillate vertically as a function of time in consistency with predictions. We also detect travelling wave trains moving in the azimuthal direction of the drop surface which are consistent with hydrothermal waves at a different combination of Reynolds, Prandtl and Evaporation than previously observed. This is the first time that wave-trains have been observed in water, being extremely challenging to detect both interferometrically and with infra-red cameras. We also find that such waves apply a force parallel to the interface along the propagation direction., Comment: 5 pages

Published
2019
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11. Roadmap for optical tweezers

Author

NASA Innovative Advanced Concepts, Australian Research Council, Japan Society for the Promotion of Science, Boğaziçi Üniversity, Novo Nordisk UK Research Foundation, Knut and Alice Wallenberg Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Universidad Autónoma de Madrid, Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil), Universidade Federal do Ceará, Agenzia Spaziale Italiana, Istituto Nazionale di Astrofisica, Agence Nationale de la Recherche (France), Wellcome Trust, Austrian Science Fund, Universidad Nacional Autónoma de México, European Commission, European Research Council, German Research Foundation, Natural Sciences and Engineering Research Council of Canada, Swedish Research Council, Engineering and Physical Sciences Research Council (UK), Office of Naval Research (US), National Science Foundation (US), Institute of Geology of the Czech Academy of Sciences, Czech Science Foundation, Generalitat de Catalunya, University of Münster, Department of Science and Technology (India), Human Frontier Science Program, Biotechnology and Biological Sciences Research Council (UK), Medical Research Council (UK), Danish National Research Foundation, Independent Research Fund Denmark, Beckman Institute, Associazione Italiana per la Ricerca sul Cancro, Volpe, Giovanni [0000-0001-5057-1846], Maragò, Onofrio M. [0000-0002-7220-8527], Rubinsztein-Dunlop, Halina [0000-0002-8332-2309], Stilgoe, Alexander B. [0000-0002-9299-5695], Volpe, Giorgio [0000-0001-9993-5348], Truong, Viet Giang [0000-0003-3589-7850], Chormaic, Síle Nic [0000-0003-4276-2014], Elahi, Parviz [0000-0003-3545-8436], Käll, Mikael [0000-0002-1163-0345], Callegari, Agnese [0000-0002-4488-4106], Neves, Antonio A. R. [0000-0002-2615-8573], Eismann, Jörg S. [0000-0002-2495-4613], Banzer, Peter [0000-0002-6336-6953], Roy, Basudev [0000-0003-0737-2889], Thalhammer-Thurner, Gregor [0000-0002-3948-8045], Ritsch-Marte, Monika [0000-0002-5945-546X], Pérez Castillo, Isaac0000-0001-7622-9440, Muenker, Till M. [0000-0003-3225-8746], Vos, Bart E. [0000-0002-4325-6298], Betz, Timo [0000-0002-1548-0655], Reece, Peter J. [0000-0003-4852-3735], McGloin, David [0000-0002-0075-4481], Gordon, Reuven [0000-0002-1485-6067], Bruce, Graham D. [0000-0003-3403-0614], Dholakia, Kishan [0000-0001-6534-9009], Roichman, Yael [0000-0003-1927-4506], Bobkova, Valeriia [0000-0003-4080-9069], Wittkowski, Raphael [0000-0003-4881-9173], Denz, Cornelia [0000-0002-7292-2499], Pavan Kumar, G. V. [0000-0002-4036-7187], Foti, Antonino [0000-0002-9824-3099], Donato, Maria Grazia [0000-0002-7580-3137], Gucciardi, Pietro G. [0000-0003-1826-9174], Gardini, Lucia [0000-0003-0923-9221], Kashchuk, Anatolii V. [0000-0002-2364-9393], Capitanio, Marco [0000-0002-9799-9353], Paterson, Lynn [0000-0003-0493-5041], Jones, Philip H. [0000-0002-0860-631X], Berg-Sørensen, Kirstine [0000-0002-9977-3980], Oddershede, Lene B. [0000-0003-2923-2844], Magazzù, Alessandro [0000-0003-1247-2702], Bronte Ciriza, David [0000-0002-5874-6601], Iatì, Maria Antonia [0000-0002-3576-8656], Swartzlander, Grover A. [0000-0003-3513-2225], Volpe, Giovanni, Maragò, Onofrio M., Rubinsztein-Dunlop, Halina, Pesce, Giuseppe, Stilgoe, Alexander B., Volpe, Giorgio, Tkachenko, Georgiy, Truong, Viet Giang, Chormaic, Síle Nic, Kalantarifard, Fatemeh, Elahi, Parviz, Käll, Mikael, Callegari, Agnese, Marqués, Manuel I., Neves, Antonio A. R., Moreira, Wendel L., Fontes, Adriana, César, Carlos L., Saija, Rosalba, Saidi, Abir, Beck, Paul, Eismann, Jörg S., Banzer, Peter, Fernandes, Thales F. D., Pedaci, Francesco, Bowen, Warwick P., Vaippully, Rahul, Lokesh, Muruga, Roy, Basudev, Thalhammer-Thurner, Gregor, Ritsch-Marte, Monika, Pérez García, Laura, Arzola, Alejandro V., Pérez Castillo, Isaac, Argun, Aykut, Muenker, Till M., Vos, Bart E., Betz, Timo, Cristiani, Ilaria, Minzioni, Paolo, Reece, Peter J., Wang, Fan, McGloin, David, Ndukaife, Justus C., Quidant, Romain, Roberts, Reece P., Laplane, Cyril, Volz, Thomas, Gordon, Reuven, Hanstorp, Dag, Tello Marmolejo, Javier, Bruce, Graham D., Dholakia, Kishan, Li, Tongcang, Brzobohatý, Oto, Simpson, Stephen H., Zemánek, Pavel, Ritort, Félix, Roichman, Yael, Bobkova, Valeriia, Wittkowski, Raphael, Denz, Cornelia, Pavan Kumar, G. V., Foti, Antonino, Donato, Maria Grazia, Gucciardi, Pietro G., Gardini, Lucia, Bianchi, Giulio, Kashchuk, Anatolii V., Capitanio, Marco, Paterson, Lynn, Jones, Philip H., Berg-Sørensen, Kirstine, Barooji, Younes F., Oddershede, Lene B., Pouladian, Pegah, Preece, Daryl, Adiels, Caroline Beck, De Luca, Anna Chiara, Magazzù, Alessandro, Bronte Ciriza, David, Iatì, Maria Antonia, Swartzlander, Grover A., NASA Innovative Advanced Concepts, Australian Research Council, Japan Society for the Promotion of Science, Boğaziçi Üniversity, Novo Nordisk UK Research Foundation, Knut and Alice Wallenberg Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Universidad Autónoma de Madrid, Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil), Universidade Federal do Ceará, Agenzia Spaziale Italiana, Istituto Nazionale di Astrofisica, Agence Nationale de la Recherche (France), Wellcome Trust, Austrian Science Fund, Universidad Nacional Autónoma de México, European Commission, European Research Council, German Research Foundation, Natural Sciences and Engineering Research Council of Canada, Swedish Research Council, Engineering and Physical Sciences Research Council (UK), Office of Naval Research (US), National Science Foundation (US), Institute of Geology of the Czech Academy of Sciences, Czech Science Foundation, Generalitat de Catalunya, University of Münster, Department of Science and Technology (India), Human Frontier Science Program, Biotechnology and Biological Sciences Research Council (UK), Medical Research Council (UK), Danish National Research Foundation, Independent Research Fund Denmark, Beckman Institute, Associazione Italiana per la Ricerca sul Cancro, Volpe, Giovanni [0000-0001-5057-1846], Maragò, Onofrio M. [0000-0002-7220-8527], Rubinsztein-Dunlop, Halina [0000-0002-8332-2309], Stilgoe, Alexander B. [0000-0002-9299-5695], Volpe, Giorgio [0000-0001-9993-5348], Truong, Viet Giang [0000-0003-3589-7850], Chormaic, Síle Nic [0000-0003-4276-2014], Elahi, Parviz [0000-0003-3545-8436], Käll, Mikael [0000-0002-1163-0345], Callegari, Agnese [0000-0002-4488-4106], Neves, Antonio A. R. [0000-0002-2615-8573], Eismann, Jörg S. [0000-0002-2495-4613], Banzer, Peter [0000-0002-6336-6953], Roy, Basudev [0000-0003-0737-2889], Thalhammer-Thurner, Gregor [0000-0002-3948-8045], Ritsch-Marte, Monika [0000-0002-5945-546X], Pérez Castillo, Isaac0000-0001-7622-9440, Muenker, Till M. [0000-0003-3225-8746], Vos, Bart E. [0000-0002-4325-6298], Betz, Timo [0000-0002-1548-0655], Reece, Peter J. [0000-0003-4852-3735], McGloin, David [0000-0002-0075-4481], Gordon, Reuven [0000-0002-1485-6067], Bruce, Graham D. [0000-0003-3403-0614], Dholakia, Kishan [0000-0001-6534-9009], Roichman, Yael [0000-0003-1927-4506], Bobkova, Valeriia [0000-0003-4080-9069], Wittkowski, Raphael [0000-0003-4881-9173], Denz, Cornelia [0000-0002-7292-2499], Pavan Kumar, G. V. [0000-0002-4036-7187], Foti, Antonino [0000-0002-9824-3099], Donato, Maria Grazia [0000-0002-7580-3137], Gucciardi, Pietro G. [0000-0003-1826-9174], Gardini, Lucia [0000-0003-0923-9221], Kashchuk, Anatolii V. [0000-0002-2364-9393], Capitanio, Marco [0000-0002-9799-9353], Paterson, Lynn [0000-0003-0493-5041], Jones, Philip H. [0000-0002-0860-631X], Berg-Sørensen, Kirstine [0000-0002-9977-3980], Oddershede, Lene B. [0000-0003-2923-2844], Magazzù, Alessandro [0000-0003-1247-2702], Bronte Ciriza, David [0000-0002-5874-6601], Iatì, Maria Antonia [0000-0002-3576-8656], Swartzlander, Grover A. [0000-0003-3513-2225], Volpe, Giovanni, Maragò, Onofrio M., Rubinsztein-Dunlop, Halina, Pesce, Giuseppe, Stilgoe, Alexander B., Volpe, Giorgio, Tkachenko, Georgiy, Truong, Viet Giang, Chormaic, Síle Nic, Kalantarifard, Fatemeh, Elahi, Parviz, Käll, Mikael, Callegari, Agnese, Marqués, Manuel I., Neves, Antonio A. R., Moreira, Wendel L., Fontes, Adriana, César, Carlos L., Saija, Rosalba, Saidi, Abir, Beck, Paul, Eismann, Jörg S., Banzer, Peter, Fernandes, Thales F. D., Pedaci, Francesco, Bowen, Warwick P., Vaippully, Rahul, Lokesh, Muruga, Roy, Basudev, Thalhammer-Thurner, Gregor, Ritsch-Marte, Monika, Pérez García, Laura, Arzola, Alejandro V., Pérez Castillo, Isaac, Argun, Aykut, Muenker, Till M., Vos, Bart E., Betz, Timo, Cristiani, Ilaria, Minzioni, Paolo, Reece, Peter J., Wang, Fan, McGloin, David, Ndukaife, Justus C., Quidant, Romain, Roberts, Reece P., Laplane, Cyril, Volz, Thomas, Gordon, Reuven, Hanstorp, Dag, Tello Marmolejo, Javier, Bruce, Graham D., Dholakia, Kishan, Li, Tongcang, Brzobohatý, Oto, Simpson, Stephen H., Zemánek, Pavel, Ritort, Félix, Roichman, Yael, Bobkova, Valeriia, Wittkowski, Raphael, Denz, Cornelia, Pavan Kumar, G. V., Foti, Antonino, Donato, Maria Grazia, Gucciardi, Pietro G., Gardini, Lucia, Bianchi, Giulio, Kashchuk, Anatolii V., Capitanio, Marco, Paterson, Lynn, Jones, Philip H., Berg-Sørensen, Kirstine, Barooji, Younes F., Oddershede, Lene B., Pouladian, Pegah, Preece, Daryl, Adiels, Caroline Beck, De Luca, Anna Chiara, Magazzù, Alessandro, Bronte Ciriza, David, Iatì, Maria Antonia, and Swartzlander, Grover A.

Abstract

Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.

Published
2023

12. Interface engineering towards high conductivity of a model organic plastic micro-surface by microbubble lithography.

Author

Ranjan, Anand Dev, Sen, Rakesh, Vaippully, Rahul, Kumar, Sumeet, Dutta, Soumya, Roy, Basudev, Mukherjee, Goutam Dev, Roy, Soumyajit, and Banerjee, Ayan

Abstract

The engineering of interfaces can play a critical role in the defining emergent fundamental properties of matter, such as high conductivity. Microbubble lithography (MBL) – having established a niche in self-assembly based micropatterning – has facilitated diverse applications in numerous domains of science, ranging from catalysis, through bio-detectors, to plastic conductors. Here, we report, for the first time, direct evidence of the effects of interface engineering of various substrates achieved using MBL. While our technique can be applied generally, we choose a model organic plastic, viz., a polymer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), as a representative organic system to demonstrate its efficacy. Thus, we observe a giant enhancement in the conductivity of PEDOT:PSS compared to the pristine sample (140 S cm−1), when we fabricate permanent patterns of the polymer on glass, followed by a PDMS substrate. While the conductivity of PEDOT:PSS on glass is enhanced by around 5 times (694 S cm−1), we obtain further improvement to 2844 S cm−1 by depositing it layer by layer (LbL) on a flexible PDMS substrate, without the use of external doping agents or invasive chemical treatment. Probing the patterned interface we observe that MBL is able to tune the conformational states of PEDOT:PSS from coils (in the pristine form) to extended coils on glass. The conformational states are almost linear in PDMS due to its more malleable liquid-like interface, which leads to considerable restructuring resulting in higher ordering and vanishing grain boundaries so that the highest conductivity is obtained in this case. Our present results demonstrate MBL as a tool for interface engineering to tailor emergent properties such as giant conductivity induced by interface restructuring. This could lead to the development of high-efficiency flexible electronics, and be applied in the fabrication of heterostructures which may eventually be used to develop electronic devices using conducting polymers. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Comparison of thermal and athermal dynamics of the cell membrane slope fluctuations in the presence and absence of Latrunculin-B

Author

Roy, Srestha, primary, Vaippully, Rahul, additional, Lokesh, Muruga, additional, Nalupurackal, Gokul, additional, Yadav, Vandana, additional, Chakraborty, Snigdhadev, additional, Gopalakrishnan, Manoj, additional, Edwin, Privita Edwina Rayappan George, additional, Bajpai, Saumendra Kumar, additional, and Roy, Basudev, additional

Published
2023
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15. Simultaneous Optical Trapping and Electromagnetic Micromanipulation of Ferromagnetically Doped NaYF4 Microparticles

Author

Nalupurackal, Gokul, primary, Murugan, Gunaseelan, additional, Lokesh, Muruga, additional, Vaippully, Rahul, additional, Chauhan, Amit, additional, Nanda, Birabar Ranjit Kumar, additional, Sudakar, Chandran, additional, Kotamarthi, Hema Chandra, additional, Datta, Priyankan, additional, Sinha Mahapatra, Pallab, additional, Jannasch, Anita, additional, Schäffer, Erik, additional, Jayaraman, Senthilselvan, additional, and Roy, Basudev, additional

Published
2023
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21. Rapid and one-step mechanochemical ligand exchange of Yb3+/Er3+ co-doped NaGdF4 upconversion nanoparticles for efficient MR and CT imaging.

Author

Jayamole, Anjusha A., Ganeshan, Jagan E., Sundaram, Thirunavukkarasu, Vaippully, Rahul, Roy, Basudev, Mohan, Pandi, Swaminathan, Dhanapandian, and Narendran, Krishnakumar

Subjects
PHOTON upconversion, COMPUTED tomography, MAGNETIC resonance imaging, DOPING agents (Chemistry), NANOPARTICLES, OLEIC acid
Abstract

Upconversion nanoparticles possess the ability to convert low energy photons to high energy photons, with the advantages of no autofluorescence, reduced photodamage, deeper tissue penetration, and extended photostability. Therefore, upconversion nanoparticles are considered ideal probes for framing potential theranostic agents. Generally, oleic acid has been used as a capping agent to fabricate high-quality upconversion nanoparticles. However, the hydrophobic oleic acid ligands on the surface of the nanoparticles continue to be a barrier when used in biological applications. Herein, we modified the surface of oleic acid coated upconversion (OA-NaGdF4:Yb/Er) nanoparticles to be hydrophilic using a novel one-step solvent assisted mechanochemical (SAM) milling ligand exchange strategy. Normal ligand exchange processes are tedious and take one to two days to complete, but the SAM ligand exchange strategy presented here is facile, rapid, and takes less than 1 h. This surface modified citric acid coated upconversion (CA-NaGdF4:Yb/Er) nanoparticles further ensures dispersibility in water and good biocompatibility, as revealed by electron microscopy, ATR-FTIR spectroscopy, zeta potential measurement, upconversion luminescence studies, and cytotoxicity assessment. Besides, the size and shape of the nanoparticles were retained after surface modification. Moreover, the monodispersed CA-NaGdF4:Yb/Er nanoparticles exhibit intrinsic paramagnetic behavior which makes them suitable to be used as a contrast enhancer for T1-weighted MRI. In addition, the measured CT numbers (in HU) increased linearly with increasing the concentration of the surface modified CA-NaGdF4:Yb/Er nanoparticles, indicating their plausibility as a CT contrast agent. The current findings suggest that the SAM ligand exchange strategy could be used to fabricate hydrophilic and biocompatible upconversion nanoparticles for bioimaging applications. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
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27. Rapid and one-step mechanochemical ligand exchange of Yb3+/Er3+co-doped NaGdF4upconversion nanoparticles for efficient MR and CT imaging

Author

Jayamole, Anjusha A., Ganeshan, Jagan E., Sundaram, Thirunavukkarasu, Vaippully, Rahul, Roy, Basudev, Mohan, Pandi, Swaminathan, Dhanapandian, and Narendran, Krishnakumar

Abstract

Upconversion nanoparticles possess the ability to convert low energy photons to high energy photons, with the advantages of no autofluorescence, reduced photodamage, deeper tissue penetration, and extended photostability. Therefore, upconversion nanoparticles are considered ideal probes for framing potential theranostic agents. Generally, oleic acid has been used as a capping agent to fabricate high-quality upconversion nanoparticles. However, the hydrophobic oleic acid ligands on the surface of the nanoparticles continue to be a barrier when used in biological applications. Herein, we modified the surface of oleic acid coated upconversion (OA-NaGdF4:Yb/Er) nanoparticles to be hydrophilic using a novel one-step solvent assisted mechanochemical (SAM) milling ligand exchange strategy. Normal ligand exchange processes are tedious and take one to two days to complete, but the SAM ligand exchange strategy presented here is facile, rapid, and takes less than 1 h. This surface modified citric acid coated upconversion (CA-NaGdF4:Yb/Er) nanoparticles further ensures dispersibility in water and good biocompatibility, as revealed by electron microscopy, ATR-FTIR spectroscopy, zeta potential measurement, upconversion luminescence studies, and cytotoxicity assessment. Besides, the size and shape of the nanoparticles were retained after surface modification. Moreover, the monodispersed CA-NaGdF4:Yb/Er nanoparticles exhibit intrinsic paramagnetic behavior which makes them suitable to be used as a contrast enhancer for T1-weighted MRI. In addition, the measured CT numbers (in HU) increased linearly with increasing the concentration of the surface modified CA-NaGdF4:Yb/Er nanoparticles, indicating their plausibility as a CT contrast agent. The current findings suggest that the SAM ligand exchange strategy could be used to fabricate hydrophilic and biocompatible upconversion nanoparticles for bioimaging applications.

Published
2023
Full Text
View/download PDF

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