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Fernandez-Rodriguez MA, Orozco-Barrera S, Sun W, Gámez F, Caro C, García-Martín ML, Rica RA. Hot Brownian Motion of Thermoresponsive Microgels in Optical Tweezers Shows Discontinuous Volume Phase Transition and Bistability. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2301653. [PMID: 37158287 DOI: 10.1002/smll.202301653] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/03/2023] [Indexed: 05/10/2023]
Abstract
Microgels are soft microparticles that often exhibit thermoresponsiveness and feature a transformation at a critical temperature, referred to as the volume phase transition temperature. Whether this transformation occurs as a smooth or as a discontinuous one is still a matter of debate. This question can be addressed by studying individual microgels trapped in optical tweezers. For this aim, composite particles are obtained by decorating Poly-N-isopropylacrylamide (pNIPAM) microgels with iron oxide nanocubes. These composites become self-heating when illuminated by the infrared trapping laser, performing hot Brownian motion within the trap. Above a certain laser power, a single decorated microgel features a volume phase transition that is discontinuous, while the usual continuous sigmoidal-like dependence is recovered after averaging over different microgels. The collective sigmoidal behavior enables the application of a power-to-temperature calibration and provides the effective drag coefficient of the self-heating microgels, thus establishing these composite particles as potential micro-thermometers and micro-heaters. Moreover, the self-heating microgels also exhibit an unexpected and intriguing bistability behavior above the critical temperature, probably due to partial collapses of the microgel. These results set the stage for further studies and the development of applications based on the hot Brownian motion of soft particles.
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Affiliation(s)
- Miguel Angel Fernandez-Rodriguez
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
- Laboratory of Surface and Interface Physics, Department of Applied Physics, Faculty of Sciences, Universidad de Granada, Campus de Fuentenueva s/n, 18071, Granada, Spain
- Research Unit Modeling Nature (MNat), Universidad de Granada, Granada, Spain
| | - Sergio Orozco-Barrera
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
| | - Wei Sun
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
- Department of Physics, Yanshan University, Qinhuangdao, 066004, China
| | - Francisco Gámez
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
| | - Carlos Caro
- Department of Physical Chemistry, Faculty of Chemical Sciences, Complutense University of Madrid, 28040, Madrid, Spain
| | - María L García-Martín
- Department of Physical Chemistry, Faculty of Chemical Sciences, Complutense University of Madrid, 28040, Madrid, Spain
- Instituto de Investigación Bioméadica de Málaga y Plataforma en Nanomedicina (IBIMA Plataforma BIONAND), C/ Severo Ochoa, 35, 29590, Málaga, Spain
- Biomedical Research Networking Center in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN), 28029, Madrid, Spain
| | - Raúl Alberto Rica
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
- Research Unit Modeling Nature (MNat), Universidad de Granada, Granada, Spain
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Lu D, Retama JR, Marin R, Marqués MI, Calderón OG, Melle S, Haro-González P, Jaque D. Thermoresponsive Polymeric Nanolenses Magnify the Thermal Sensitivity of Single Upconverting Nanoparticles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2202452. [PMID: 35908155 DOI: 10.1002/smll.202202452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/29/2022] [Indexed: 06/15/2023]
Abstract
Lanthanide-based upconverting nanoparticles (UCNPs) are trustworthy workhorses in luminescent nanothermometry. The use of UCNPs-based nanothermometers has enabled the determination of the thermal properties of cell membranes and monitoring of in vivo thermal therapies in real time. However, UCNPs boast low thermal sensitivity and brightness, which, along with the difficulty in controlling individual UCNP remotely, make them less than ideal nanothermometers at the single-particle level. In this work, it is shown how these problems can be elegantly solved using a thermoresponsive polymeric coating. Upon decorating the surface of NaYF4 :Er3+ ,Yb3+ UCNPs with poly(N-isopropylacrylamide) (PNIPAM), a >10-fold enhancement in optical forces is observed, allowing stable trapping and manipulation of a single UCNP in the physiological temperature range (20-45 °C). This optical force improvement is accompanied by a significant enhancement of the thermal sensitivity- a maximum value of 8% °C+1 at 32 °C induced by the collapse of PNIPAM. Numerical simulations reveal that the enhancement in thermal sensitivity mainly stems from the high-refractive-index polymeric coating that behaves as a nanolens of high numerical aperture. The results in this work demonstrate how UCNP nanothermometers can be further improved by an adequate surface decoration and open a new avenue toward highly sensitive single-particle nanothermometry.
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Affiliation(s)
- Dasheng Lu
- Nanomaterials for Bioimaging Group (NanoBIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Nanomaterials for Bioimaging Group (NanoBIG), Instituto Ramón y Cajal de Investigación Sanitaria, IRYCIS, Ctra. Colmenar km. 9.100, Madrid, 28034, Spain
| | - Jorge Rubio Retama
- Nanomaterials for Bioimaging Group (NanoBIG), Instituto Ramón y Cajal de Investigación Sanitaria, IRYCIS, Ctra. Colmenar km. 9.100, Madrid, 28034, Spain
- Departamento de Química en Ciencias Farmacéuticas, Facultad de Farmacia, Plaza de Ramón y Cajal, s/n, Universidad Complutense de Madrid, Madrid, 28040, Spain
| | - Riccardo Marin
- Nanomaterials for Bioimaging Group (NanoBIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Nanomaterials for Bioimaging Group (NanoBIG), Instituto Ramón y Cajal de Investigación Sanitaria, IRYCIS, Ctra. Colmenar km. 9.100, Madrid, 28034, Spain
| | - Manuel I Marqués
- Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Departamento de Física de Materiales and IFIMAC, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Oscar G Calderón
- Departamento de Óptica, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, 28037, Spain
| | - Sonia Melle
- Departamento de Óptica, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, 28037, Spain
| | - Patricia Haro-González
- Nanomaterials for Bioimaging Group (NanoBIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Daniel Jaque
- Nanomaterials for Bioimaging Group (NanoBIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Nanomaterials for Bioimaging Group (NanoBIG), Instituto Ramón y Cajal de Investigación Sanitaria, IRYCIS, Ctra. Colmenar km. 9.100, Madrid, 28034, Spain
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Gupta DK, Tata BVR, Ravindran TR. Optimization of a spatial light modulator driven by digital video interface graphics to generate holographic optical traps. APPLIED OPTICS 2018; 57:8374-8384. [PMID: 30461792 DOI: 10.1364/ao.57.008374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 09/04/2018] [Indexed: 06/09/2023]
Abstract
We propose a method to optimize spatial light modulators (SLMs) driven by digital video interface graphics in a holographic optical tweezers system. A method analogous to that used to optimize LCD televisions is used to optimize the properties of the graphics card through a diffraction-based experiment and develop a lookup table for the SLM. The optimization allows the SLM to function with its full phase modulation depth with improved diffraction efficiency. Further, we propose a simple and robust method to correct for the spatially varying phase response of the SLM to enhance its diffraction efficiency. The optimization results in an improvement of uniformity in the intensity and quality of the trap spots.
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Abstract
Combination of responsive microgels and photonic resonant nanostructures represents an intriguing technological tool for realizing tunable and reconfigurable platforms, especially useful for biochemical sensing applications. Interaction of light with microgel particles during their swelling/shrinking dynamics is not trivial because of the inverse relationships between their size and refractive index. In this work, we propose a reliable analytical model describing the optical properties of closed-packed assembly of surface-attached microgels, as a function of the external stimulus applied. The relationships between the refractive index and thickness of the equivalent microgel slab are derived from experimental observations based on conventional morphological analysis. The model is first validated in the case of temperature responsive microgels integrated on a plasmonic lab-on-fiber optrode, and also implemented in the same case study for an optical responsivity optimization problem. Overall, our model can be extended to other photonic platforms and different kind of microgels, independently from the nature of the stimulus inducing their swelling.
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