Name: facile preparation and photoactivation of prodrug-dye nanoassemblies
Uploaded: 2023-02-17T14:05:00
Description: Watch this Scientific Journal Video about Facile Preparation and Photoactivation of Prodrug-Dye Nanoassemblies at JoVE.com

We acknowledge assistance from the University of Hong Kong Li Ka Shing Faculty of Medicine Faculty Core Facility. We thank Professor Chi-Ming Che at the University of Hong Kong for providing the human HCT116 cell line. This work was supported by Ming Wai Lau Centre for Reparative Medicine Associate Member Program and the Research Grants Council of Hong Kong (Early Career Scheme, No. 27115220).

1. Synthesis of boron-dipyrromethene-chlorambucil (BC) prodrug (Figure 2)22
<ol>
	<li>Synthesis of BODIPY-OAc
	<ol>
		<li>Weigh 1.903 g of 2,4-dimethyl pyrrole and dissolve it in 20 mL of anhydrous dichloromethane (DCM) in a round-bottom flask under a nitrogen atmosphere. Weigh 1.638 g of acetoxy acetyl chloride and add it dropwise into the solution. Keep stirring for 10 min at room temperature and then reflux the solution for 1 h a...

<ol>
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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strategies+for+enzyme/prodrug+cancer+therapy.">Strategies for enzyme/prodrug cancer therapy.</a> Clinical Cancer Research. 7 (11), 3314-3324 (2001).</li><li>Luo, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dual-targeted+and+pH-sensitive+doxorubicin+prodrug-microbubble+complex+with+ultrasound+for+tumor+treatment.">Dual-targeted and pH-sensitive doxorubicin prodrug-microbubble complex with ultrasound for tumor treatment.</a> Theranostics. 7 (2), 452 (2017).</li><li>Gao, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasound+triggered+phase-change+nanodroplets+for+doxorubicin+prodrug+delivery+and+ultrasound+diagnosis:+An+in+vitro+study.">Ultrasound triggered phase-change nanodroplets for doxorubicin prodrug delivery and ultrasound diagnosis: An in vitro study.</a> Colloids and Surfaces B: Biointerfaces. 174, 416-425 (2019).</li><li>Brade, A. M., Szmitko, P., Ngo, D., Liu, F. -. F., Klamut, H. 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This protocol outlines a facile flash precipitation method for the fabrication of prodrug-dye nanoparticles, which offers a simple and convenient approach for nanoparticle formation. There are several critical steps in this method. Firstly, for all steps of synthesis, fabrication, and characterization, containers like microtubes should be covered with foil to avoid unnecessary photocleavage of the BC prodrug by environmental light. Moreover, in the flash precipitation step, the microtube containing the IR-783 solution sh...

Chemotherapy is a common cancer treatment that employs cytotoxic agents to kill cancer cells and thus inhibits tumor growth1. However, patients may suffer from side effects such as cardiotoxicity and hepatotoxicity due to the off-target absorption of the chemotherapy drugs2,3,4. Therefore, localized drug delivery through the spatiotemporal control of drug release/activation in tumors is essential to minimize drug exposure in normal tissues.
Prodrugs are chemically modified drugs that exhibit reduced toxicity in normal tissues while retaining their action in diseased lesions upon activation5,6. Prodrugs can be responsive to a variety of stimuli, such as pH7,8, enzymes9,10, ultrasound11,12, heat13, and light14,15,16, and release their parent drugs specifically in the lesions. Nevertheless, many prodrugs exhibit inherent drawbacks, such as poor solubility, incorrect absorption rate, and early metabolic destruction, which may limit their development17. In this context, the formation of prodrug nanoassemblies offers advantages like decreased side effects, in situ drug release, better retention, and the combination of treatment and imaging, indicating great application potential for these nanoassemblies. Many prodrug nanoassemblies have been developed for disease treatment, including doxorubicin prodrug nanospheres, curcumin prodrug micelles, and camptothecin prodrug nanofibers18.
In this protocol, we present a simple method for the preparation of prodrug-dye nanoassemblies that exhibit high prodrug content, good water dispersibility, long-term stability, and sensitive responding ability. IR783 is a water soluble near-infrared dye that can serve as stabilizer of the nanoassemblies19. The other component of the nanoassembly is boron-dipyrromethene-chlorambucil (BODIPY-Cb, BC), a prodrug that was designed for two main reasons. As chlorambucil (Cb) displays systemic toxicity in vivo, the prodrug form can decrease its toxicity20. The BC prodrug can be photocleaved using 530 nm light irradiation directed at disease lesions, enabling the local release of Cb. On the other hand, Cb is prone to hydrolysis in aqueous environments, and can be protected by transforming it into a prodrug form21. Thus, the co-assembly of the BC prodrug and IR-783 dye was expected to form a stable and effective drug delivery nanosystem (Figure 1A). This prodrug-dye nanoassembly improves the dispersibility and stability of the prodrug molecules, suggesting its potential for application in light-controllable drug delivery. The photocleavage of the BC prodrug enables the disassembly of nanoparticles and the light-controlled release of Cb in the lesions (Supplemental Figure 1).

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1260 Infinity II HPLC</td>
			<td>Agilent Technologies</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2,4-Dimethyl pyrrole</td>
			<td>J&#38;K Scientific</td>
			<td>315305</td>
			<td></td>
		</tr>
		<tr>
			<td>3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)</td>
			<td>Gibco</td>
			<td>M6494</td>
			<td></td>
		</tr>
		<tr>
			<td>4-Dimethylaminopyridine (4-DMAP)</td>
			<td>J&#38;K Scientific</td>
			<td>212279</td>
			<td></td>
		</tr>
		<tr>
			<td>90 mm Petri Dish Clear Treated Sterile</td>
			<td>SPL</td>
			<td>11090</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well Tissue Culture Plate Clear Treated Sterile</td>
			<td>SPL</td>
			<td>30096</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetoxyacetyl chloride</td>
			<td>J&#38;K Scientific</td>
			<td>192001</td>
			<td></td>
		</tr>
		<tr>
			<td>Boron trifluoride diethyl etherate</td>
			<td>J&#38;K Scientific</td>
			<td>921076</td>
			<td></td>
		</tr>
		<tr>
			<td>B&#252;chner funnel</td>
			<td>AS ONE</td>
			<td>3-6466-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Chlorambucil</td>
			<td>J&#38;K Scientific</td>
			<td>321407-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>CM100 Transmission Electron Microscope</td>
			<td>Philips</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CombiFlash RF chromatography system&#160;</td>
			<td>Teledyne ISCO</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dichloromethane</td>
			<td>DUKSAN Pure Chemicals</td>
			<td>JT9315-88</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide</td>
			<td>DUKSAN Pure Chemicals</td>
			<td>2762</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable cuvette</td>
			<td>Malvern Panalytical</td>
			<td>DTS1070</td>
			<td>Zeta potential measurement</td>
		</tr>
		<tr>
			<td>Disposable cuvette</td>
			<td>Malvern Panalytical</td>
			<td>ZEN0040</td>
			<td></td>
		</tr>
		<tr>
			<td>Empty Disposable Sample Load Cartridges</td>
			<td>Teledyne ISCO</td>
			<td>693873225</td>
			<td>can hold up to 65 g</td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>Gibco</td>
			<td>10270106</td>
			<td></td>
		</tr>
		<tr>
			<td>Filtering flask</td>
			<td>AS ONE</td>
			<td>3-7089-03</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexane</td>
			<td>DUKSAN Pure Chemicals</td>
			<td>4198</td>
			<td></td>
		</tr>
		<tr>
			<td>Holey carbon film on copper grid</td>
			<td>Beijing Zhongjingkeyi Technology Co.,Ltd</td>
			<td>BZ10023a</td>
			<td></td>
		</tr>
		<tr>
			<td>HPLC column (InfinityLab Poroshell 120)</td>
			<td>Agilent Technologies</td>
			<td>695975-902T</td>
			<td></td>
		</tr>
		<tr>
			<td>Integrating sphere photodiode power sensor</td>
			<td>Thorlabs</td>
			<td>S142C</td>
			<td></td>
		</tr>
		<tr>
			<td>IR783</td>
			<td>Tokyo Chemical Industry (TCI) Co., Ltd</td>
			<td>I1031</td>
			<td></td>
		</tr>
		<tr>
			<td>LED&#160;</td>
			<td>Mightex</td>
			<td>LCS-0530-15-11</td>
			<td></td>
		</tr>
		<tr>
			<td>LED Driver Control Panel V3.2.0 (Software)</td>
			<td>Mightex</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lithium Hydroxide Anhydrous</td>
			<td>TCI</td>
			<td>L0225</td>
			<td></td>
		</tr>
		<tr>
			<td>Methylmagnesium iodide, 3M solution in diethyl ether</td>
			<td>Aladdin</td>
			<td>M140783</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N-Diisopropyl ethyl amine (DIPEA)</td>
			<td>J&#38;K Scientific</td>
			<td>203402</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N&#39;-Dicyclohexylcarbodiimide (DCC)</td>
			<td>J&#38;K Scientific</td>
			<td>275928</td>
			<td></td>
		</tr>
		<tr>
			<td>penicillin&#8211;streptomycin</td>
			<td>Gibco</td>
			<td>15140122</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-buffered saline (10&#215;)</td>
			<td>&#160;Sigma-Aldrich</td>
			<td>P5493</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;Power and energy meter&#160;</td>
			<td>Thorlabs</td>
			<td>PM100 USB</td>
			<td></td>
		</tr>
		<tr>
			<td>Rotavapor</td>
			<td>BUCHI Rotavapor R300</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>RMPI 1640</td>
			<td>Gibco</td>
			<td>21870076</td>
			<td></td>
		</tr>
		<tr>
			<td>Separatory funnel (125 mL)</td>
			<td>Synthware</td>
			<td>F474125L</td>
			<td></td>
		</tr>
		<tr>
			<td>Silver Silica Gel Disposable Flash Columns, 40 g</td>
			<td>Teledyne ISCO</td>
			<td>692203340</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium sulfate, anhydrous</td>
			<td>Alfa Aesar</td>
			<td>A19890</td>
			<td></td>
		</tr>
		<tr>
			<td>SpectraMax M4</td>
			<td>Molecular Devices LLC</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrahydrofuran (THF), anhydrous</td>
			<td>J&#38;K Scientific</td>
			<td>943616</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.25%), phenol red</td>
			<td>Gibco</td>
			<td>25200056</td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex</td>
			<td>DLAB Scientific Co., Ltd</td>
			<td>MX-S</td>
			<td></td>
		</tr>
		<tr>
			<td>Zetasizer Nano ZS90&#160;</td>
			<td>Malvern Instrument</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

facile preparation and photoactivation of prodrug-dye nanoassemblies

Self-assembly is a simple yet reliable method for constructing nanoscale drug delivery systems. Photoactivatable prodrugs enable controllable drug release from nanocarriers at target sites modulated by light irradiation. In this protocol, a facile method for fabricating photoactivatable prodrug-dye nanoparticles via molecular self-assembly is presented. The procedures for prodrug synthesis, nanoparticle fabrication, physical characterization of the nanoassembly, photocleavage demonstration, and in vitro cytotoxicity verification are described in detail. A photocleavable boron-dipyrromethene-chlorambucil (BC) prodrug was first synthesized. BC and a near-infrared dye, IR-783, at an optimized ratio, could self-assemble into nanoparticles (IR783/BC NPs). The synthesized nanoparticles had an average size of 87.22 nm and a surface charge of -29.8 mV. The nanoparticles disassembled upon light irradiation, which could be observed by transmission electronic microscopy. The photocleavage of BC was completed within 10 min, with a 22% recovery efficiency for chlorambucil. The nanoparticles displayed enhanced cytotoxicity under light irradiation at 530 nm compared with the non-irradiated nanoparticles and irradiated free BC prodrug. This protocol provides a reference&#160;for the construction and evaluation of photoresponsive drug delivery systems.

IR783/BC NPs were successfully fabricated in this study using a flash precipitation method. The synthesized IR783/BC NPs presented as a purple solution, while the aqueous solution of IR783 was blue (Figure 4A). As shown in Figure 4B, the IR783/BC NPs exhibited an average size of approximately 87.22 nm with a polydispersity index (PDI) of 0.089, demonstrating a narrow size distribution. The surface charge of the IR783/NPs was approximately -29.8 mV (<strong class...

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Facile Preparation and Photoactivation of Prodrug-Dye Nanoassemblies

This protocol describes the fabrication and characterization of a photoresponsive prodrug-dye nanoassembly. The methodology for drug release from the nanoparticles by light-triggered disassembly, including the light irradiation setup, is explicitly described. The drugs released from the nanoparticles following light irradiation exhibited excellent anti-proliferation effects on human colorectal tumor cells.

Self-assembly is a simple yet reliable method for constructing nanoscale drug delivery systems. Photoactivatable prodrugs enable controllable drug release ...

This protocol provides a reference on construction and characterization of photo responsive drug-dye systems, especially the setup of light radiation. This technique shows the advantage of simple fabrication, high drug loading capacity, and photo controlability. This technique can be used to treat colorectal tumor with the help of optical fiber to deliver lights for activating the drug release at the tumor site.Begin by weighing 10 milligrams of the boron dipyrromethene chlorambucil or BC prodrug and dissolve it in one milliliter of dimethyl sulfoxide, or DMSO, in a 1.5-milliliter micro tube. Cover the BC solution with foil then prepare 0.4 milligrams per milliliter IR783 in filtered deionized water and transfer 300 microliters in a 1.5-milliliter micro tube. Place this micro tube on a vortex mixer at 1500 RPM.Next with the end of the 20 microliters pipette tip touching the inner wall of the micro tube, add 20 microliters of the BC solution to the IR783 solution over 10 seconds at a constant rate. Place the micro tube on the vortex mixer for 30 seconds to obtain the IR783/BC nanoparticles. Then place the nanoparticle solution on a rack fully covered with foil.Centrifuge the resulting IR783/BC nanoparticle solution for 10 minutes at 2000 G and four degrees Celsius to remove aggregates. Collect the supernatant, leaving approximately 20 microliters in the tube to avoid disturbing the pellet before discarding it. After centrifuging the supernatant two times for 30 minutes at 30, 000 G and 4 degrees Celsius, collect the nanoparticle precipitate from both centrifications.Resuspend the nanoparticles in 300 microliters of PBS. Quantify the content of IR783 and BC by high-performance liquid chromatography, or HPLC, using the elution method. Calculate the prodrug encapsulation efficiency, or EE percent, and loading capacity or, LC percent.To measure the average size of the IR783/BC nanoparticles with a dynamic light scattering, or DLS, instrument. Add 200 microliters of IR783/BC nanoparticle solution in a cuvette and insert the cuvette in the holder for measurement. Set the measurement type as size and the measurement temperature as 25 degrees Celsius.Perform three measurements with a duration of 20 seconds for each measurement. To measure the surface charge of the IR783/BC nanoparticles with the DLS instrument, dilute 25 microliters of IR783/BC nanoparticle solution with 725 microliters of deionized water in a 1.5-milliliter micro tube. Add the solution into a zeta potential test cuvette.Place the cuvette in the sample groove. Cap the sample groove. Next, set the measurement type as zeta potential and the temperature as 25 degrees Celsius.Perform 10 measurements. Once done, prepare the samples for transmission electron microscopy, or TEM, imaging by adding 10 microliters of IR783/BC nanoparticle solution on a piece of the holey carbon film on a copper grid of 300 mesh and removing seven microliters from the holey carbon film. Leave three microliters of solution on the film overnight for auto evaporation.Set up an LED lamp at 530 nanometers with an iron stand so that the light directly faces the operating floor. Place an integrating sphere photodiode photometer directly under the LED lamp. Turn on the LED lamp and open the cap of the photometer.Record the irradiance. Set the lamp parameters using the associated software and adjust the input current in the milliampere to set the irradiance as 50 milliwatts per square centimeter. Dilute the IR783/BC nanoparticle solution with deionized water to 50 micromolar, based on BC concentration.Add 200 micromolar IR783/BC nanoparticle solution into a 1.5-milliliter micro tube. Place the tube on a foam block having a groove fitting the size of the micro tube and at the same height as the photometer. Open the cap of the tube.Switch on the LED lamp and irradiate the nanoparticle solution for 1, 2, 3, 5, 7, and 10 minutes. After light irradiation, quantify BC consumption and Cb release by HPLC and calculate the remaining BC and Cb release. IR783/BC nanoparticles were successfully fabricated in this study using a flash precipitation method.The synthesized nanoparticles were present as a purple solution while the aqueous solution of IR783 was blue. The IR783/BC nanoparticles exhibited an average size of 87.22 nanometers with a polydispersity index, or PDI, of 0.089;demonstrating a narrow size distribution. The surface charge was approximately minus 29.8 millivolts, indicating the negatively charged sulfonate groups of IR783.The nanoparticle size was maintained at 85 nanometers for at least 48 hours after fabrication, while its PDI remained less than 0.2. No significant change was observed in the size distribution at 0, 24 and 48 hours after fabrication. Aggregates and fragments were observed after lighter irradiation.Size and distribution changes were observed after three and five minutes of light irradiation. Prodrug BC was photo cleaved in 10 minutes. Meanwhile, chlorambucil was released with a recovery efficiency of around 22%within the same period.The IR783/BC nanoparticles displayed significant cytotoxicity on human colorectal tumor cells HCT 116 under light irradiation at 530 nanometers compared with the non-irradiation group. It is important to touch the inner wall of the micro tube tightly with the end of the peptides and place the micro tube on the vortex stably.

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Research

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Medicine

Do's and Don'ts in the Preparation of Muscle Cryosections for Histological Analysis

Histological evaluation of muscle biopsies has served as an indispensable tool in the understanding of the development and progression of pathology of neuromuscular disorders. However, in order to do so, proper care needs to be taken when excising and preserving tissues to achieve optimal staining. One method of tissue preservation involves fixing tissues in formaldehyde and then embedding them with paraffin wax. This method preserves morphology well and allows for long-term storage at RT but is cumbersome and requires handling of toxic chemicals. Further, formaldehyde fixation results in antigen cross-linking, which necessitates antigen retrieval protocols for effective immunostaining. On the contrary, frozen sectioning does not require fixation and thus retains biological antigen conformation. This method also provides a distinct advantage in quick turn around time, making it especially useful in situations needing quick histological evaluation like intraoperative surgical biopsies. Here we describe the most effective method of preparing muscle biopsies for visualization with different histological and immunological stains.

Do&#039;s and Don&#039;ts in the Preparation of Muscle Cryosections for Histological Analysis

Here we demonstrate the most efficient methods for freezing, embedding, cryosectioning, and staining of muscle biopsies to avoid freezing artifacts.

Histological evaluation of muscle biopsies has served as an indispensable tool in the understanding of the development and progression of pathology of ...

Preparation and In Vitro Characterization of Magnetized miR-modified Endothelial Cells

To date, the available surgical and pharmacological treatments for cardiovascular diseases (CVD) are limited and often palliative. At the same time, gene and cell therapies are highly promising alternative approaches for CVD treatment. However, the broad clinical application of gene therapy is greatly limited by the lack of suitable gene delivery systems. The development of appropriate gene delivery vectors can provide a solution to current challenges in cell therapy. In particular, existing drawbacks, such as limited efficiency and low cell retention in the injured organ, could be overcome by appropriate cell engineering (i.e., genetic) prior to transplantation. The presented protocol describes the efficient and safe transient modification of endothelial cells using a polyethyleneimine superparamagnetic magnetic nanoparticle (PEI/MNP)-based delivery vector. Also, the algorithm and methods for cell characterization are defined. The successful intracellular delivery of microRNA (miR) into human umbilical vein endothelial cells (HUVECs) has been achieved without affecting cell viability, functionality, or intercellular communication. Moreover, this approach was proven to cause a strong functional effect in introduced exogenous miR. Importantly, the application of this MNP-based vector ensures cell magnetization, with accompanying possibilities of magnetic targeting and non-invasive MRI tracing. This may provide a basis for magnetically guided, genetically engineered cell therapeutics that can be monitored non-invasively with MRI.

Preparation and In Vitro Characterization of Magnetized miR-modified Endothelial Cells

This manuscript describes the efficient, non-viral delivery of miR to endothelial cells by a PEI/MNP vector and their magnetization. Thus, in addition to genetic modification, this approach allows for magnetic cell guidance and MRI detectability. The technique can be used to improve the characteristics of therapeutic cell products.

To date, the available surgical and pharmacological treatments for cardiovascular diseases (CVD) are limited and often palliative. At the same time, gene ...

Preparation Of Gushukang (GSK) Granules for In Vivo and In Vitro Experiments

Traditional Chinese herbal medicine plays a role as an alternative method in treating many diseases, such as postmenopausal osteoporosis (POP). Gushukang (GSK) granules, a marketed prescription in China, have bone-protective effects in treating POP. Before administration to the body, one standard preparation procedure is commonly required, which aims to promote the release of active constituents from raw herbs and enhance the pharmacological effects as well as therapeutic outcomes. This study proposes a detailed protocol for using GSK granules in in vivo and in vitro experimental assays. The authors first provide a detailed protocol to calculate the animal-appropriate dosages of granules for in vivo investigation: weighing, dissolving, storage, and administration. Second, this article describes protocols for micro-CT scanning and the measurement of bone parameters. Sample preparation, protocols for running the micro-CT machine and quantification of bone parameters were evaluated. Third, serum-containing GSK granules are prepared, and drug-containing serum is extracted for in vitro osteoclastogenesis and osteoblastogenesis. GSK granules were intragastrically administered twice per day to rats for three consecutive days. Blood was then collected, centrifuged, inactivated, and filtered. Finally, serum was diluted and used for performing osteoclastogenesis and osteoblastogenesis. The protocol described here can be considered a reference for pharmacological investigations of herbal prescription medicines, such as granules.

Preparation Of Gushukang GSK Granules for In Vivo and In Vitro Experiments

This article provides a detailed protocol for preparing a working solution of Gushukang granules for animal studies and GSK granule containing serum for in vitro experiments. This protocol can be applied to pharmacological investigations of herbal medicines as well as prescriptions for both in vivo and in vitro experiments.

Traditional Chinese herbal medicine plays a role as an alternative method in treating many diseases, such as postmenopausal osteoporosis (POP). Gushukang ...

Preparation of Decellularized Kidney Scaffolds in Rats

Tissue engineering is a cutting-edge discipline in biomedicine. Cell culture techniques can be applied for regeneration of functional tissues and organs to replace diseased or damaged organs. Scaffolds are needed to facilitate the generation of three-dimensional organs or tissues using differentiated stem cells in vivo. In this report, we describe a novel method for developing vascularized scaffolds using decellularized rat kidneys. Eight-week-old Sprague-Dawley rats were used in this study, and heparin was injected into the heart to facilitate flow into the renal vessels, allowing heparin to perfuse into the renal vessels. The abdominal cavity was opened, and the left kidney was collected. The collected kidneys were perfused for 9 h using detergents, such as Triton X-100 and sodium dodecyl sulfate, to decellularize the tissue. Decellularized kidney scaffolds were then gently washed with 1% penicillin/streptomycin and heparin to remove cellular debris and chemical residues. Transplantation of stem cells with the decellularized vascular scaffolds is expected to facilitate the generation of new organs. Thus, the vascularized scaffolds may provide a foundation for tissue engineering of organ grafts in the future.

This protocol introduces a method to develop a scaffold using decellularized rat kidneys. The protocol includes decellularization and recellularization processes to confirm bioavailability. Decellularization is performed using Triton X-100 and sodium dodecyl sulfate.

Tissue engineering is a cutting-edge discipline in biomedicine. Cell culture techniques can be applied for regeneration of functional tissues and organs ...

Biological Preparation and Mechanical Technique for Determining Viscoelastic Properties of Zonular Fibers

Elasticity is essential to the function of tissues such as blood vessels, muscles, and lungs. This property is derived mostly from the extracellular matrix (ECM), the protein meshwork that binds cells and tissues together. How the elastic properties of an ECM network relate to its composition, and whether the relaxation properties of the ECM play a physiological role, are questions that have yet to be fully addressed. Part of the challenge lies in the complex architecture of most ECM systems and the difficulty in isolating ECM components without compromising their structure. One exception is the zonule, an ECM system found in the eye of vertebrates. The zonule comprises fibers hundreds to thousands of micrometers in length that span the cell-free space between the lens and the eyewall. In this report, we describe a mechanical technique that takes advantage of the highly organized structure of the zonule to quantify its viscoelastic properties and to determine the contribution of individual protein components. The method involves dissection of a fixed eye to expose the lens and the zonule and employs a pull-up technique that stretches the zonular fibers equally while their tension is monitored. The technique is relatively inexpensive yet sensitive enough to detect alterations in viscoelastic properties of zonular fibers in mice lacking specific zonular proteins or with aging. Although the method presented here is designed primarily for studying ocular development and disease, it could also serve as an experimental model for exploring broader questions regarding the viscoelastic properties of elastic ECM&#39;s and the role of external factors such as ionic concentration, temperature, and interactions with signaling molecules.

The protocol describes a method for the study of extracellular matrix viscoelasticity and its dependence on protein composition or environmental factors. The matrix system targeted is the mouse zonule. The performance of the method is demonstrated by comparing the viscoelastic behavior of wild-type zonular fibers with those lacking microfibril-associated glycoprotein-1.

Elasticity is essential to the function of tissues such as blood vessels, muscles, and lungs. This property is derived mostly from the extracellular ...

Guided Endodontics: Three-Dimensional Planning and Template-Aided Preparation of Endodontic Access Cavities

Pulp canal obliterations (PCO) are often a consequence of dental trauma, such as luxation injuries. Even though dentin apposition is a sign of vital pulp, pulpitis or apical periodontitis may develop in the long term. Root canal treatment of teeth with severe PCO and pulpal or periapical pathosis is challenging for general practitioners and even for well-equipped endodontic specialists. To ensure detection of the calcified root canal and avoid excessive loss of tooth structure or root perforation, static navigation using templates ("Guided Endodontics") was introduced a few years ago. The general workflow includes three-dimensional imaging using cone-beam computed tomography (CBCT), a digital surface scan, and superimposition of both in a planning software. This is followed by virtual planning of the access cavity and the design of a template that will guide the drill to the desired target point. To do this, a true-to-scale virtual image of the drill must be placed in a way that the tip of the drill reaches the orifice of the calcified root canal. Once the template has been fabricated using computer-aided design and computer-aided manufacturing (CAD/CAM) or a 3D printer, guided preparation of the access cavity can be performed clinically. For research purposes, a postoperative CBCT image can be used to quantify the accuracy of the access cavity performed. This work aims to present the technique of static guided endodontics from imaging to clinical implementation.

Guided endodontics describes a template-aided approach for access cavity preparation. The procedure requires cone-beam computed tomography and a surface scan to produce a template. An incorporated sleeve guides the drill to the target point. This allows the preparation of minimally invasive endodontic access cavities in calcified teeth.

Pulp canal obliterations (PCO) are often a consequence of dental trauma, such as luxation injuries. Even though dentin apposition is a sign of vital pulp, ...

Preparation and Heating of the Phantom Material Mixture 

Begin the sonication of 0.15 grams of titanium dioxide and one milliliter of the absorber dye stock solution in 100 milliliters of mineral oil at 90 degrees Celsius for 60 minutes. Let all the components dissolve completely. Use suitable glassware and silicone oil to create an oil bath and carefully secure it on the hot plate.For uniform heat distribution, place a magnetic stir bar inside the oil bath. Turn on the hot plate, set the heating temperature to 160 degrees Celsius and adjust the stir to 50 RPM. Next, weigh 25.14 grams of SEBS and 6.70 grams of LDPE and transfer them into the glass beaker containing the sonicated mineral oil.Place a stir bar in the beaker and transfer it to the center of the oil bath to heat the measured components. When the added polymers float over the mineral oil, manually stir the mineral oil solution using a metal spatula and distribute the floating polymer inside the mineral oil. Leave the mixture at 160 degrees Celsius for 1.5 hours until all the polymer is dissolved and the solution appears uniformly mixed, smooth, and homogenous.

Internal Jugular Vein Identification and Catheter Exit Site Preparation

To begin, place the anesthetized swine on the operating table. In the ventral field, make a four-centimeter incision between the trachea and the medial border of the sternocleidomastoid muscle. Divide the platysma and dissect the connective tissue to expose the internal jugular vein, or IJV, on the lateral border of the sternocleidomastoid muscle.Then isolate three to four centimeters of the IJV by dividing its branches with 4.0 coated and braided non-absorbable suture ties. Circumferentially dissect away from the surrounding connective tissue. At the cranial end of the IJV, pass a coated and braided non-absorbable suture tie twice underneath the vessel to create a loop around it.At the coddle end, pass a suture tie once underneath the vessel to create a sling. For catheter exit site preparation. Reposition the swine via lateral tilt toward the non-surgical side to expose the ipsilateral dorsal surgical field.Once the limbs are resecured, with a number 10 blade scalpel, make a 0.5 centimeter puncture in the skin at the desired catheter exit site, three centimeters lateral to the vertebral column, and five centimeter coddle to the head.

Preparation of Working Solution and Semen Sample for Leukocyte Analysis

Pre-Scan Preparation and Coaching of Subject for 129Xe MRI of Lung Ventilation

To begin, prepare one or more Tedlar bags, containing air, for the subject to practice outside the scanner. Use an air volume that matches the total volume of xenon and buffer gas to be inhaled from the bag during the actual study. Prepare nose clips for the subject to wear during breath hold scanning, fit the nose clips onto the subject's nose before the start of breath holds.Use one air-filled bag for each attempt to coach the subject. Before producing the bag, ask the subject to breathe in and breathe out regularly several times. During the procedure, monitor the subject's chest to confirm that they are executing the instructions properly.Next, place the tube attached to the Tedlar bag into the subject's mouth. Hold the bag such that the subject can inhale from it and open the valve. Ask the subject to breathe in, then ask the subject to hold their breath by saying, hold your breath.When practicing, wait for a count of 10 to 15 seconds, which is the approximate amount of time required for a typical xenon 129 scan to elapse. After that, ask the subject to exhale at this point and breathe. Coach the subject to take several deep breaths in and out for a quicker clearance of xenon 129 from the lungs and a quicker return to normal oxygen saturation levels.Verify that the subject is able to carry out the instructions reliably and consider excluding subjects who cannot do so during practice runs.