scholarly journals Magnetically Powered Biodegradable Microswimmers

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 404 ◽  
Author(s):  
Ho Cheung Michael Sun ◽  
Pan Liao ◽  
Tanyong Wei ◽  
Li Zhang ◽  
Dong Sun
Keyword(s):  
Magnetic Field ◽  
Biomedical Applications ◽  
Structural Integrity ◽  
Propulsive Efficiency ◽  
Two Photon ◽  
Laser Lithography ◽  
Undulatory Locomotion ◽  
Oscillating Magnetic Field ◽  
Novel Design

The propulsive efficiency and biodegradability of wireless microrobots play a significant role in facilitating promising biomedical applications. Mimicking biological matters is a promising way to improve the performance of microrobots. Among diverse locomotion strategies, undulatory propulsion shows remarkable efficiency and agility. This work proposes a novel magnetically powered and hydrogel-based biodegradable microswimmer. The microswimmer is fabricated integrally by 3D laser lithography based on two-photon polymerization from a biodegradable material and has a total length of 200 μm and a diameter of 8 μm. The designed microswimmer incorporates a novel design utilizing four rigid segments, each of which is connected to the succeeding segment by spring to achieve undulation, improving structural integrity as well as simplifying the fabrication process. Under an external oscillating magnetic field, the microswimmer with multiple rigid segments connected by flexible spring can achieve undulatory locomotion and move forward along with the directions guided by the external magnetic field in the low Reynolds number (Re) regime. In addition, experiments demonstrated that the microswimmer can be degraded successfully, which allows it to be safely applied in real-time in vivo environments. This design has great potential in future in vivo applications such as precision medicine, drug delivery, and diagnosis.

scholarly journals ID: 4001 Nanoparticle-based Cancer Therapy

2017 ◽  
Vol 4 (S) ◽  
pp. 2
Author(s):  
Fuyu Tamanoi
Keyword(s):  
Magnetic Field ◽  
Iron Oxide ◽  
Cancer Therapy ◽  
Cancer Cells ◽  
Anticancer Drugs ◽  
Tumor Targeting ◽  
Two Photon ◽  
Pore Opening ◽  
Oscillating Magnetic Field ◽  
The Way

Advances in Nanotechnology have led to the development of a variety of nanomaterials that are changing the way cancer therapy is carried out. A particularly important example is nanoparticle that can carry cargo to tumor. We are using mesoporous silica nanoparticles (MSNs) for cancer therapy. MSNs contain thousands of pores that provide storage space for anticancer drugs. These materials are biocompatible and safe. In addition, we have recently introduced biodegradability into MSNs.  We have shown that MSNs exhibit excellent tumor targeting capability in two different animal model systems (chicken egg tumor model and mouse xenografts). This tumor targeting capability is partly due to its small size; these nano-sized particles can accumulate in tumor due to leaky tumor vasculature. In addition, we have carried out surface modifications to attach ligands that bind receptors present on the surface of cancer cells. For example, folate was attached to the surface that enables binding to folate receptors overexpressed on cancer cells.  We have also conferred controlled anticancer drug release capability to MSNs in collaboration with Fraser Stoddart and Jeff Zink. This was accomplished by attaching nanovalves at the opening of the pores. Rotaxanes and pseudorotaxanes are used to prepare nanovalves. These chemical compounds consist of a stalk and a moving part. When the moving part is close to the pore opening, the nanovalve is closed. On the other hand, when the moving part is located away from the pore opening, the nanovalve is closed. In this way, the nanovalve provides an open and close function so that controlled release of anticancer drugs can be carried out.  Light activated nanovalves were developed by incorporating azobenzene into nanovalves. Azobenzene changes conformation upon light exposure and this conformational change opens the nanovalve releasing anticancer drugs in a power and exposure time dependent manner. More recently, this system was modified by incorporating two-photon dyes that can capture energy from two-photon light and transfer to azobenzene to drive the release of anticancer drugs. This enables the system to work with tissue penetrating two-photon light.  We have also developed nanoparticles that respond to oscillating magnetic field. This system was developed using MSNs that contain iron oxide core. Because of superparamagnetic property of iron oxide, the internal temperature of such nanoparticles increases when exposed to oscillating magnetic field. This temperature increase drives opening of nanovalves that are particularly designed for this purpose.   Development of nanoparticles that respond to external cues such as light and magnetic field may change the way cancer therapy is carried out. Implications on the future of cancer therapy will be discussed.

scholarly journals High-throughput cellular-resolution synaptic connectivity mapping in vivo with concurrent two-photon optogenetics and volumetric Ca2+ imaging

2020 ◽  
Author(s):  
Christopher McRaven ◽  
Dimitrii Tanese ◽  
Lixia Zhang ◽  
Chao-Tsung Yang ◽  
Misha B. Ahrens ◽  
...  
Keyword(s):  
High Throughput ◽  
Synaptic Connectivity ◽  
Whole Cell ◽  
Two Photon ◽  
Whole Cell Recording ◽  
Connectivity Mapping ◽  
Cellular Resolution ◽  
Cell Recording ◽  
Undulatory Locomotion

AbstractThe ability to measure synaptic connectivity and properties is essential for understanding neuronal circuits. However, existing methods that allow such measurements at cellular resolution are laborious and technically demanding. Here, we describe a system that allows such measurements in a high-throughput way by combining two-photon optogenetics and volumetric Ca2+ imaging with whole-cell recording. We reveal a circuit motif for generating fast undulatory locomotion in zebrafish.

Spectroscopic imaging of human disease

1996 ◽  
Vol 54 ◽  
pp. 884-885
Author(s):  
D.J. Meyerhoff
Keyword(s):  
Magnetic Field ◽  
Magnetic Resonance ◽  
Field Gradient ◽  
Human Disease ◽  
Morphological Changes ◽  
Magnetic Field Gradient ◽  
Spectroscopic Imaging ◽  
Resonance Spectroscopy ◽  
Tissue Water

Magnetic Resonance Imaging (MRI) observes tissue water in the presence of a magnetic field gradient to study morphological changes such as tissue volume loss and signal hyperintensities in human disease. These changes are mostly non-specific and do not appear to be correlated with the range of severity of a certain disease. In contrast, Magnetic Resonance Spectroscopy (MRS), which measures many different chemicals and tissue metabolites in the millimolar concentration range in the absence of a magnetic field gradient, has been shown to reveal characteristic metabolite patterns which are often correlated with the severity of a disease. In-vivo MRS studies are performed on widely available MRI scanners without any “sample preparation” or invasive procedures and are therefore widely used in clinical research. Hydrogen (H) MRS and MR Spectroscopic Imaging (MRSI, conceptionally a combination of MRI and MRS) measure N-acetylaspartate (a putative marker of neurons), creatine-containing metabolites (involved in energy processes in the cell), choline-containing metabolites (involved in membrane metabolism and, possibly, inflammatory processes),

Biomedical applications: Pitfalls in the practice

1994 ◽  
Vol 52 ◽  
pp. 378-379
Author(s):  
J. D. Shelburne ◽  
Peter Ingram ◽  
Victor L. Roggli ◽  
Ann LeFurgey
Keyword(s):  
Operating Room ◽  
Liquid Nitrogen ◽  
Lung Tissue ◽  
Biomedical Applications ◽  
Microprobe Analysis ◽  
Tissue Sample ◽  
Cellular Level ◽  
Tissue Samples ◽  
Asbestos Fibers

At present most medical microprobe analysis is conducted on insoluble particulates such as asbestos fibers in lung tissue. Cryotechniques are not necessary for this type of specimen. Insoluble particulates can be processed conventionally. Nevertheless, it is important to emphasize that conventional processing is unacceptable for specimens in which electrolyte distributions in tissues are sought. It is necessary to flash-freeze in order to preserve the integrity of electrolyte distributions at the subcellular and cellular level. Ideally, biopsies should be flash-frozen in the operating room rather than being frozen several minutes later in a histology laboratory. Electrolytes will move during such a long delay. While flammable cryogens such as propane obviously cannot be used in an operating room, liquid nitrogen-cooled slam-freezing devices or guns may be permitted, and are the best way to achieve an artifact-free, accurate tissue sample which truly reflects the in vivo state. Unfortunately, the importance of cryofixation is often not understood. Investigators bring tissue samples fixed in glutaraldehyde to a microprobe laboratory with a request for microprobe analysis for electrolytes.

Biological and biomedical applications of collagenous biomaterials

1990 ◽  
Vol 48 (3) ◽  
pp. 856-857
Author(s):  
Yasushi P. Kato ◽  
Michael G. Dunn ◽  
Frederick H. Silver ◽  
Arthur J. Wasserman
Keyword(s):  
Biomedical Applications ◽  
Soft Tissues ◽  
Collagen Fibers ◽  
Bone Collagen ◽  
Cover Slip ◽  
Fibroblast Migration ◽  
Cellular Expression ◽  
Defect Repair

Collagenous biomaterials have been used for growing cells in vitro as well as for augmentation and replacement of hard and soft tissues. The substratum used for culturing cells is implicated in the modulation of phenotypic cellular expression, cellular orientation and adhesion. Collagen may have a strong influence on these cellular parameters when used as a substrate in vitro. Clinically, collagen has many applications to wound healing including, skin and bone substitution, tendon, ligament, and nerve replacement. In this report we demonstrate two uses of collagen. First as a fiber to support fibroblast growth in vitro, and second as a demineralized bone/collagen sponge for radial bone defect repair in vivo.For the in vitro study, collagen fibers were prepared as described previously. Primary rat tendon fibroblasts (1° RTF) were isolated and cultured for 5 days on 1 X 15 mm sterile cover slips. Six to seven collagen fibers, were glued parallel to each other onto a circular cover slip (D=18mm) and the 1 X 15mm cover slip populated with 1° RTF was placed at the center perpendicular to the collagen fibers. Fibroblast migration from the 1 x 15mm cover slip onto and along the collagen fibers was measured daily using a phase contrast microscope (Olympus CK-2) with a calibrated eyepiece. Migratory rates for fibroblasts were determined from 36 fibers over 4 days.

In vivo imaging of liver injury and regeneration by functional two-photon microscopy

2016 ◽  
Vol 54 (12) ◽  
pp. 1343-1404
Author(s):  
A Ghallab ◽  
R Reif ◽  
R Hassan ◽  
AS Seddek ◽  
JG Hengstler
Keyword(s):  
Liver Injury ◽  
In Vivo Imaging ◽  
Two Photon Microscopy ◽  
Two Photon

Intense Static Magnetic Field Induced Bone Growth in Vivo

1984 ◽  
Vol 3 (1) ◽  
pp. 223-234
Author(s):  
Frank Papatheofanis ◽  
Bill Fapatheofanls ◽  
Robert Ray
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Bone Growth

Conjugates of Classical DNA/RNA Binder with Nucleobase: Chemical, Biochemical and Biomedical Applications

2019 ◽  
Vol 26 (30) ◽  
pp. 5609-5624
Author(s):  
Dijana Saftić ◽  
Željka Ban ◽  
Josipa Matić ◽  
Lidija-Marija Tumirv ◽  
Ivo Piantanida
Keyword(s):  
Molecular Weight ◽  
Small Molecules ◽  
Biomedical Applications ◽  
Protein Targets ◽  
New Class ◽  
Rna Targets ◽  
Covalently Linked ◽  
Structural Aspects

: Among the most intensively studied classes of small molecules (molecular weight < 650) in biomedical research are small molecules that non-covalently bind to DNA/RNA, and another intensively studied class is nucleobase derivatives. Both classes have been intensively elaborated in many books and reviews. However, conjugates consisting of DNA/RNA binder covalently linked to nucleobase are much less studied and have not been reviewed in the last two decades. Therefore, this review summarized reports on the design of classical DNA/RNA binder – nucleobase conjugates, as well as data about their interactions with various DNA or RNA targets, and even in some cases protein targets are involved. According to these data, the most important structural aspects of selective or even specific recognition between small molecule and target are proposed, and where possible related biochemical and biomedical aspects were discussed. The general conclusion is that this, rather new class of molecules showed an amazing set of recognition tools for numerous DNA or RNA targets in the last two decades, as well as few intriguing in vitro and in vivo selectivities. Several lead research lines show promising advancements toward either novel, highly selective markers or bioactive, potentially druggable molecules.

scholarly journals High-speed volumetric two-photon fluorescence imaging of neurovascular dynamics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiang Lan Fan ◽  
Jose A. Rivera ◽  
Wei Sun ◽  
John Peterson ◽  
Henry Haeberle ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Fluorescence Signal ◽  
Imaging Method ◽  
Spatiotemporal Resolution ◽  
Two Photon

AbstractUnderstanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.

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