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Proceedings ArticleDOI

Mechanical characterization of erythrocyte-derived optical microparticles by quantitative phase imaging and optical tweezers

04 Mar 2019-Vol. 10887, pp 1088717
TL;DR: Differences in membrane stiffness suggest that the circulation dynamics of μNETs may be altered as compared to native erythrocytes, and may play an important role in the circulation kinetics and biodistribution of these particles.
Abstract: We have fabricated constructs from erythrocytes that contain the near-infrared (NIR) dye, indocyanine green (ICG). We refer to these constructs as NIR erythrocyte mimicking transducers (NETs). Mechanical properties of NETs can play an important role in the circulation kinetics and biodistribution of these particles. We characterize the mechanical properties of erythrocytes, hemoglobin-depleted erythrocytes ghosts (EGs), and micron-sized NETs (μNETs) through analysis of membrane fluctuations measured by quantitative phase imaging, and forces associated with membrane tethers pulled by optical tweezers. EGs were prepared from erythrocytes by hypotonic treatment. μNETs were prepared through hypotonic loading of 25 μM ICG into EGs. Quantitative phase images were obtained by a common-path interferometric phaseshifting system. Approximating the membrane as a sheet of springs, we estimated the stiffness of the membrane of erythrocytes, EGs, and µNETs as 3.0 ± 0.6 pN/μm, 6.5 ± 2.1 pN/μm, and 8.0 ± 2.1 pN/μm. Optical tweezers experiments yielded a similar trend. Differences in membrane stiffness suggest that the circulation dynamics of μNETs may be altered as compared to native erythrocytes.
Citations
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Journal ArticleDOI
TL;DR: A hybrid system to encapsulate CPT inside the amphiphilic micelle and coat it with RBC membrane is developed, which resulted in the increased overall survival of mice treated with the nano formulation and showed strong retention inside the Ehrlich Ascites Carcinoma mice models for at least 72 h, suggesting camouflaging ability conferred by RBC membranes.

26 citations

Journal ArticleDOI
TL;DR: This work investigated the circulation dynamics of micro and nano-sized erythrocyte-derived carriers in real time using near-infrared fluorescence imaging, and evaluated the effectiveness of such carrier systems in mediating photothermolysis of cutaneous vasculature in mice.
Abstract: Erythrocyte-based carriers can serve as theranostic platforms for delivery of imaging and therapeutic payloads. Engineering these carriers at micro- or nanoscales makes them potentially useful for broad clinical applications ranging from vascular diseases to tumor theranostics. Longevity of these carriers in circulation is important in delivering a sufficient amount of their payloads to the target. We have investigated the circulation dynamics of micro (∼4.95 μm diameter) and nano (∼91 nm diameter) erythrocyte-derived carriers in real time using near-infrared fluorescence imaging, and evaluated the effectiveness of such carrier systems in mediating photothermolysis of cutaneous vasculature in mice. Fluorescence emission half-lives of micro- and nanosized carriers in response to a single intravenous injection were ∼49 and ∼15 min, respectively. A single injection of microsized carriers resulted in a 3-fold increase in signal-to-noise ratio that remained nearly persistent over 1 h of imaging time. Our results also suggest that a second injection of the carriers 7 days later can induce a transient inflammatory response, as manifested by the apparent leakage of the carriers into the perivascular tissue. The administration of the carriers into the mice vasculature reduced the threshold laser fluence to induce photothermolysis of blood vessels from >65 to 20 J/cm2. We discuss the importance of membrane physicochemical and mechanical characteristics in engineering erythrocyte-derived carriers and considerations for their clinical translation.

15 citations

References
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Journal ArticleDOI
22 Feb 2013-PLOS ONE
TL;DR: The results of this study elucidate the coordination of plasma membrane composition and cytoskeleton during protrusion formation and make a major contribution to protrusion mechanics as evidenced by the effects of F-actin disruption on the resulting mechanical parameters.
Abstract: Protrusions are deformations that form at the surface of living cells during biological activities such as cell migration. Using combined optical tweezers and fluorescent microscopy, we quantified the mechanical properties of protrusions in adherent human embryonic kidney cells in response to application of an external force at the cell surface. The mechanical properties of protrusions were analyzed by obtaining the associated force-length plots during protrusion formation, and force relaxation at constant length. Protrusion mechanics were interpretable by a standard linear solid (Kelvin) model, consisting of two stiffness parameters, k0 and k1 (with k0>k1), and a viscous coefficient. While both stiffness parameters contribute to the time-dependant mechanical behavior of the protrusions, k0 and k1 in particular dominated the early and late stages of the protrusion formation and elongation process, respectively. Lowering the membrane cholesterol content by 25% increased the k0 stiffness by 74%, and shortened the protrusion length by almost half. Enhancement of membrane cholesterol content by nearly two-fold increased the protrusion length by 30%, and decreased the k0 stiffness by nearly two-and-half-fold as compared with control cells. Cytoskeleton integrity was found to make a major contribution to protrusion mechanics as evidenced by the effects of F-actin disruption on the resulting mechanical parameters. Viscoelastic behavior of protrusions was further characterized by hysteresis and force relaxation after formation. The results of this study elucidate the coordination of plasma membrane composition and cytoskeleton during protrusion formation.

58 citations

Journal ArticleDOI
Joonseok Hur1, Kyoohyun Kim1, SangYun Lee1, HyunJoo Park1, YongKeun Park1 
TL;DR: Here, the actions of melittin, the active molecule of apitoxin or bee venom, were investigated on human red blood cells (RBCs) using quantitative phase imaging techniques and high-resolution real-time 3-D refractive index measurements and dynamic 2-D phase images enabled in-depth examination ofmelittin-induced biophysical alterations of the cells.
Abstract: Here, the actions of melittin, the active molecule of apitoxin or bee venom, were investigated on human red blood cells (RBCs) using quantitative phase imaging techniques. High-resolution real-time 3-D refractive index (RI) measurements and dynamic 2-D phase images of individual melittin-bound RBCs enabled in-depth examination of melittin-induced biophysical alterations of the cells. From the measurements, morphological, intracellular, and mechanical alterations of the RBCs were analyzed quantitatively. Furthermore, leakage of haemoglobin (Hb) inside the RBCs at high melittin concentration was also investigated.

42 citations

Journal ArticleDOI
TL;DR: The results provide support for the effectiveness of NETs as theranostic agents for fluorescence imaging and photodestruction of tumors and their role in photoinduced apoptosis initiated by their localization to lysosomes.
Abstract: Nanoparticles activated by near-infrared (NIR) excitation provide a capability for optical imaging and photodestruction of tumors. We have engineered optical nanoconstructs derived from erythrocytes, which are doped with the FDA-approved NIR dye, indocyanine green (ICG). We refer to these constructs as NIR erythrocyte-mimicking transducers (NETs). Herein, we investigate the phototheranostic capabilities of NETs for fluorescence imaging and photodestruction of SKBR3 breast cancer cells and subcutaneous xenograft tumors in mice. Our cellular studies demonstrate that NETs are internalized by these cancer cells and localized to their lysosomes. As evidenced by NIR fluorescence imaging and in vivo laser irradiation studies, NETs remain available within tumors at 24 h postintravenous injection. In response to continuous wave 808 nm laser irradiation at intensity of 680 mW/cm2 for 10-15 min, NETs mediate the destruction of cancer cells and tumors in mice through synergistic photochemical and photothermal effects. We demonstrate that NETs are effective in mediating photoactivation of Caspase-3 to induce tumor apoptosis. Our results provide support for the effectiveness of NETs as theranostic agents for fluorescence imaging and photodestruction of tumors and their role in photoinduced apoptosis initiated by their localization to lysosomes.

30 citations

Journal ArticleDOI
TL;DR: S spatial light interference microscopy is employed to perform high-accuracy single-cell phase imaging and decouple the average thickness and refractive index information for the population and shows that the thickness profile of the cell tail goes down to 150 nm and theRefractive index can reach values of 1.6 close to the head.
Abstract: Characterization of spermatozoon viability is a common test in treating infertility. Recently, it has been shown that label-free, phase-sensitive imaging can provide a valuable alternative for this type of assay. We employ spatial light interference microscopy (SLIM) to perform high-accuracy single-cell phase imaging and decouple the average thickness and refractive index information for the population. This procedure was enabled by quantitative-phase imaging cells on media of two different refractive indices and using a numerical tool to remove the curvature from the cell tails. This way, we achieved ensemble averaging of topography and refractometry of 100 cells in each of the two groups. The results show that the thickness profile of the cell tail goes down to 150 nm and the refractive index can reach values of 1.6 close to the head.

18 citations

PatentDOI
TL;DR: An all-optical platform delivering pN force resolution in parallel with nano-scale structural imaging of the biological sample by combining optical tweezers with interferometric quantitative phase microscopy, opening avenues to a wide range of new research possibilities and applications in biology.
Abstract: Various embodiments disclosed relate to a system. According to various embodiments the present disclosure provides a system. The system includes a movable sample stage configured to receive a sample. The movable sample stage includes a first major surface and a second major surface opposite the first major surface. A portion of the first major surface and the second major surface can be transparent. An excitation light source is aligned with and is in optical communication with the first major surface of the sample stage. A microscope objective is disposed on the second major surface and is substantially aligned with the excitation light source. A laser source is in optical communication with the sample stage. A dichroic mirror is aligned with the microscope objective and is configured to direct light emitted from the laser in a first direction towards the microscope objective.

9 citations


"Mechanical characterization of eryt..." refers methods in this paper

  • ...Our QPI system is described in details in a previous publication.(8) Briefly, the sample was illuminated by light from a halogen lamp source filtered to have peak wavelength of 595 nm....

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