جستجوی مقالات مرتبط با کلیدواژه « microfluidics » در نشریات گروه « پزشکی »

 A new analytical method based on the coupling of microextraction and microfluidics was developed and investigated for the pre-concentration, separation, and electrochemical detection of fenitrothion (FT) and parathion (PA) at the sub-ppm concentrations.

 In the first step, the microchip capillary electrophoresis technique was used to serve as a separation and detection system. Analytes were injected in the 40 mm long microchannel with 10 mm sidearms. Then, they were separated by applying a direct electrical field (+1800 V) between the buffer and detection reservoirs. 2-(n-morpholino)ethanesulfonic acid (MES) buffer (20 mM, pH 5) was used as a running buffer. The electrochemical detection was performed using three Pt microelectrodes with the width of working, counter, and reference electrodes (50, 250, and 250 µm, respectively) in the out-channel approach.

 The system was devised to have the optimum detection potential equal to -1.2 V vs. pseudo-reference electrode. The dimensions of the SU-8 channel have 20 µm depth and 50 µm width. In the second step, an air-assisted liquid-liquid microextraction technique was used to extract and preconcentration of analytes from human blood plasma. Then, 1, 2 di-bromoethan was used as extractant solvent, the analytes were preconcentrated, and the sedimented solvent (50 µL) was evaporated in a 60 ˚C water bath followed by substitution of running buffer containing 10% ethanol. The optimal extraction cycles were found to be 8 with adding 1% NaCl to the aqueous phase. Analyzing time of the mentioned analytes was less than 100s, the precision range was 3.3 – 8.2 with a linear range of 0.8–100 ppm and 1.2–100 ppm for FT and PA, respectively. The extraction recoveries were about 91% and 87% for FT and PA, respectively. The detection limits for FT and PA were 240 and 360 ppb, respectively. Finally, the reliability of the method was investigated by GC-FID.

 The proposed method and device were validated and can be used as in situ and portable detection systems for detecting fenitrothion and parathion insecticides.

Sperm DNA fragmentation can affect reproductive outcomes in assisted reproductive techniques (ART), and it is a concern in density gradient centrifugation (DGC). By contrast, microfluidic approaches allow the selection of highly motile sperm with low DNA fragmentation index (DFI). The purpose of current study, was to compare the efficacy of a microfluidic device designed in-house in comparison with DGC.

Nineteen healthy men with normal semen profiles were included in the study. Semen samples were individually aliquoted for three sperm preparation analyses (crude and processed with to either DGC or the microfluidic method). Sperm parameters of the samples were evaluated along with DNA fragmentation using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) method.

Sperm processed using the microfluidic method showed a significantly lower DFI than those obtained using DGC and in crude semen, with DFI of 1.1%, 3.5%, and 4.9%, respectively. Although the microfluidic method yielded significantly lower sperm concentrations than DGC, no significant differences were observed in total motility, progressive motility, curvilinear velocity, straight-line velocity, or normal morphology.

Using the in-house microfluidic device, sperm with lower DFI was effectively isolated when compared with DGC. The motility and normal morphology rates were comparable among the samples.

The molecular marker, cardiac troponin (cTn) is a complex protein that is attached to tropomyosin on the actin filament. It is an essential biomolecule in terms of the calcium-mediated regulation of the contractile apparatus in myofibrils, the release of which is an indication of the dysfunction of cardiomyocytes and hence the initiation of ischemic phenomena in the heart tissue. Fast and accurate analysis of cTn may help the diagnosis and management of acute myocardial infarction (AMI), for which electrochemical biosensors and microfluidics devices can be of great benefit. This editorial aims to highlight the importance of cTn as vital biomarkers in AMI diagnosis.

The inability of classic fluorescence-activated cell sorting to single cancer cell sorting is one of the most significant drawbacks of this method. The sorting of cancer cells in microdroplets significantly influences our ability to analyze cancer cell proteins.

We adapted a developed microfluidic device as a 3D in vitro model to sorted MCF-7 cancer cells on a chip. A prefabricated microfluidic droplet chip was used in this research. Then, with the help of synthesized fluorescent probes, MCF-7 cancer cells were separated from normal cells.

This research presents a modification of GQD bead for high-throughput analysis and sorting single cancer cells. We elaborate a binding assay as an example of this approach for detecting MCF-7 cancer cell lines. Graphene quantum dot-decorated mesoporous silica nanoparticles (GQD@MSNPs) act as fluorescent optical beads coated in microfluidic droplets. The fluorescent beads capture cancer cells. To enable droplet sorting at 200 Hz and cell enrichment, a measurable fluorescence signal is generated when cancer cells bind to these beads and boost the drop's fluorescence emission.

Herein, we report in vitro results showing that the as-prepared GQD@MSNs have exceptional luminous characteristics. The specific surface area and pore volume of GQD-MSNs were found to be 50% and 40% higher than those of pure MSNs, which is rather remarkable. Because of these improved qualities, GQD@MSNs are demonstrated a large sorting capacity that makes them ideal for diagnosis.

Microfluidics (MF) is the science dealing with the behavior, precise control, and manipulation of fluids as well as particles on the scale of tens to hundreds of micrometers. It is also utilized for chemical and biological applications, usually called micro–total analysis systems (µTAS) or lab-on-a-chip (LOC). MF is a fascinating and capable technology with various superior benefits compared to conventional macro-scale platforms, such as the lesser requirement of sample and reagent volumes, higher sensitivity, low cost, portability, faster processing of samples and potential to be automated and highly integrated to reduce human errors. The concept of transformation of meso to nanoliters using MF technology has shown its potential in the healthcare system for early diagnosis, and personalized medicine. The integrated multifunctional system with parallelization provides a better and faster process control. Minimization of the consumption of fluid makes the technology safer in every aspect of the development process, analysis, and storage. The impressive improvement in patient care and monitoring has led to the commercial motivation of the pharmaceutical industry to develop new drugs and modify existing products with better efficacy and safety in a cost-effective manner using MF technologies. Hence, the present review briefs on the applications of MF technology in the key issues of the drug discovery process, overcoming the limitations of development of analytical procedures and prosperous pharmaceutical manufacturing for novel controlled and targeted release dosage forms to fabricate quality products.

Surgery is the standard treatment for breast malignancies, although local and distant relapses might occur. Previous studies have shown that surgery-induced wound fluid (WF) contains tumor-initiating and progressing factors; however, these experiments have only been performed on breast cancer cell lines. Since a cancerous tumor includes various components like malignant cells, recruited non-malignant cells and extracellular matrix, those investigations that only focused on cancer cell lines themselves are not adequate to establish WF’s effects. We conducted a 3D model study where we mimicked the tumor microenvironment to re-assess previous in-vitro findings. We generated human-derived breast tumor spheroids from 23 patient specimens, dissociated and cultured them in microfluidic devices. The spheroids from each sample were treated with the patients’ WF or RPMI medium. The proportion of live and dead cells was assessed using live/dead assays and fluorescent imaging on day 6. In 22 samples, the percentage of live cells was significantly higher in the WF-treated group than in the RPMI-treated group. In one sample, we observed an opposite trend. The results were contrary in one of the samples, and we reported that case with more details. We compared the two groups using the 3D culture environment of human-derived tumor spheroids prepared from different microfluidic devices to mimic the tumor environment heterogeneity. Our findings showed that most patients with breast cancer benefit from surgical wound healing. However, removal of the surgical-induced serum may not be a method of inhibiting the tumor in all patients.

Although investigating the probable side effects of post intraoperative radiotherapy wound fluid secretion (PIWFS) is crucial, especially in clinical cases, no report has been published on the effect of PIWFS on the remaining tumor cells (in the vital state) in cavity side margins or surrounding regions. These tumor cells might be directly/indirectly exposed to intraoperative radiation therapy (IORT). Here, for the first time, we investigated the effect of PIWFS on tumor cells of the same patient extracted from the excised tumor in the spheroid form.

We generated 8 human-derived breast tumor spheroids from 4 patient specimens who received to IORT, dissociated and cultured them in microfluidic devices. The spheroids from each sample were treated with the patients’ PIWFS and DMEM medium separately. Two different parameters, called area and number of detached cells (NDCs), were determined and investigated to evaluate the spheroids’ vital and proliferative states.

The results showed severe transformation in tumor spheroids’ function into more invasive and proliferative functions after treatment with PIWFS.

Although the radiation-induced bystander effect may have a role in this observation, further experiments must be done to better clarify the probable desired or non-desired effects of post-IORT secretion for both the remaining tumor cells and the surrounding immune cells.

Antibiotic resistance is one of the serious health-threatening issues globally, the control of which is indispensable for rapid diagnosis and treatment because of the high prevalence and risks of pathogenicity. Traditional and molecular techniques are relatively expensive, complex, and non-portable, requiring facilities, trained personnel, and high-tech laboratories. Widespread and timely-detection is vital to the better crisis management of rapidly spreading infective diseases, especially in low-tech regions and resource-limited settings. Hence, the need for inexpensive, fast, simple, mobile, and accessible point-of-care (POC) diagnostics is highly demanding. Among different biosensing methods, the isothermal amplification of nucleic acids is favorite due to their simplicity, high sensitivity/specificity, rapidity, and portability, all because they require a constant temperature to work. Isothermal amplification methods are utilized for detecting various targets, including DNA, RNA, cells, proteins, small molecules, ions, and viruses. In this paper, we discuss various platforms, applications, and potentials of isothermal amplification techniques for biosensing of antimicrobial resistance. We also evaluate the potential of these methods, coupled with the novel and rapidly-evolving platforms offered by nanotechnology and microfluidic devices.

A new microfluidic-based method with electrochemical detection was developed for the simultaneous quantification of acetaminophen (AP) and phenylephrine (PHE) pharmaceuticals in the human blood and pharmaceuticals (e.g. tablet and drop).

The separation was achieved on a SU8/glass microchip with a 100 µm Pt working electrode that was positioned out of the channel and 2-(N-morpholino) ethanesulfonic acid was used as a running buffer (pH 7, 10 mM). Home designed modulated high voltage power supply and dual time switcher was used for controlling the injection and separation of the analytes in the unpinched injection mode.

The injection was carried out using +750 V for 7 seconds, and the separation and detection voltages were set at +1000 V and +0.9 V, respectively. Critical parameters such as detection potential, buffer concentration, injection, and separation voltage were studied in terms of their effects on the resolution, peak height, and migration times. For each analyte, the correlation coefficients were over 0.99 (n=6). The developed microchip was able to detect AP and phenylephrine simultaneously with the limit of detection of 7.9 and 5.2 (µg/mL) respectively for PHE and AP and excellent linear range of 10-200 (µg/mL). The recovery of the drugs ranged from 96% to 103%, while the repeatability of the method through inter- and intra-day was lower than 7%.

The developed method offers several advantages, including easy sample pretreatment process, simplicity, very fast analysis compared to other typical chromatographic methods. Thus, the proposed microfluidic-based method is proposed to be used as a time- and cost-effective monitoring method for the analysis of AP and PHE.

Polymeric micelles (PMs) are one of Nanoscale delivery systems with high stability, loading capacity, and biocompatibility. PMs are nano-sized and spherical particles with a hydrophilic shell and hydrophobic core or reverse depending on their applications. Polymeric micelles could be synthesized by different methods, such as direct dissolution, dialysis method, and lyophilization. Microfluidics is also a relatively modern approach for this purpose, in which chemical reactions are carried out in the microchannels. Compared with conventional preparation methods, the microfluidic technique produces homogeneous polymeric micelles with desirable features, tunable particle size, and relatively high drug loading. These advantages are originated from the ability of microfluidics in precise control over the streamlines of reactants without chaotic turbulence. Although the synthesis of polymeric micelles by the microfluidic platform is advantageous, little or no review has been conducted to provide a clear image of the different PMs preparation by the microfluidic approach. Thus, in this review, the production of the PMs, utilizing microfluidic procedures to enhance their favorable characteristics is investigated. For this purpose, an electronic search is conducted on PubMed, Web of Science, Scopus, and Embase databases for retrieval of relevant papers. Seven papers are included in this systematic review. Preparation of PMs by the microfluidic approach and the effect of different parameters, such as the flow rate ratio, channel dimensions, drug concentration, and organic solvent type on PMs characteristics is obtained from the included papers.

In customary assisted reproductive technology (ART), oocyte culture occurs in static micro drops of Petri dishes with vast media volume; while, the in vivo condition is dynamic. In this study, we aimed to improve the maturation efficiency of mammalian oocytes by designing an optimal microchamber array to obtain the integration of oocyte trapping and maturation within a microfluidic device and evaluate the role of microfluidic culture condition in lipid peroxidation level of the culture medium, in vitro matured oocytes apoptosis, and its comparison with the conventional static system.

In this experimental research, immature oocytes were collected from ovaries of the Naval Medical Research Institute (NMRI) mice. Oocytes were randomly laid in static and dynamic (passive & active) in vitro maturation culture medium for 24 hours. The lipid peroxidation level in oocyte culture media was assessed by measuring the concentration of malondialdehyde (MDA), and the rate of apoptosis in in vitro matured oocytes was assessed by the TUNEL assay after a-24 hour maturation period.

The MDA concentration in both dynamic oocyte maturation media were significantly lower than the static medium (0.003 and 0.002 vs. 0.13 μmol/L, P<0.01). Moreover, the rate of apoptosis in matured oocytes after a-24 hour maturation period was significantly lower in passive dynamic and active dynamic groups compared with the static group (16%, 15% vs. 35%, P<0.01).

The dynamic culture for in vitro oocyte maturation (IVM) improves the viability of IVM oocytes in comparison with the static culture condition.

A key feature of the 'One Health' concept pertains to the design of novel point of care systems for largescale screening of health of the population residing in resource-limited areas of low- and middle-income countries with a view to obtaining data at a community level as a rationale to achieve better public health outcomes. The physical properties of blood are different for different samples. Our study involved the development of an innovative system architecture based upon the physical properties of blood using automated classifiers to enable large-scale screening of the health of the population living in resource-limited settings.

The proposed system consisted of a simple, robust and low-cost sensor with capabilities to sense and measure even the minute changes in the physical properties of blood samples. In this system, the viscosity of blood was derived from a power-law model coupled with the Rabinowitsch-Mooney correction for non-Newtonian shear rates developed in a steady laminar Poiseuille flow. Surface tension was measured by solving the Young-Laplace equation for pendant drop shape hanging on a vertical needle. An anticipated outcome of this study would be the development of a novel automated classifier based upon the rheological attributes of blood. This automated classifier would have potential application in evaluating the health status of a population at regional and global levels.

The proposed system was used to measure the physical properties of various samples like normal, tuberculous and anemic blood samples. The results showed that the physical properties of these samples were different as compared to normal blood samples. The major advantage of this system was low-cost, as well as its simplicity and portability.

In this work, we proposed making a case for the validation of a low-cost version of a microfluidic system capable of scanning large populations for a variety of diseases as per the WHO mandate of “One Health”.

We present a four-branch model of the dielectrophoresis (DEP) method that takes into consideration the inherent properties of particles, including size, electrical conductivity, and permittivity coefficient. By using this model, bioparticles can be continuously separated by the application of only a one-stage separation process.

In this numerical study, we based the separation process on the differences in the particle sizes. We used the various negative DEP forces on the particles caused by the electrodes to separate them with a high efficiency. The particle separator could separate blood cells because of their different sizes.

Blood cells greater than 12 μm were guided to a special branch, which improved separation efficiency because it prevented the deposition of particles in other branches. The designed device had the capability to separate blood cells with diameters of 2.0 μm, 6.2 μm, 10.0 μm, and greater than 12.0 μm. The applied voltage to the electrodes was 50 V with a frequency of 100 kHz.

The proposed device is a simple, efficient DEP-based continuous cell separator. This capability makes it ideal for use in various biomedical applications, including cell therapy and cell separation, and results in a throughput increment of microfluidics devices.

This study, for the first time, tries to provide a simultaneous experimental and computational fluid dynamic (CFD) simulation investigation for production of uniform, reproducible, and stable polylactic-co-glycolic acid (PLGA) nanoparticles. CFD simulation was carried out to observe fluid flow behavior and micromixing in microfluidic system and improve our understanding about the governing fluid profile. The major objective of such effort was to provide a carrier for controlled and sustained release profile of different drugs. Different experimental parameters were optimized to obtain PLGA nanoparticles with proper size  and minimized polydispersity index. The particle size, polydispersity, morphology, and stability of nanoparticles were compared. Microfluidic system provided a platform to control over the characteristics of nanoparticles. Using microfluidic system, the obtained particles were more uniform and harmonious in size,  more stable, monodisperse and spherical, while particles produced by batch method were non-spherical and polydisperse. The best size and polydispersity index in the microfluidic method was obtained using 2% PLGA and 0.0625% (w/v) polyvinyl alcohol (PVA) solutions, and the flow rate ratio of 10:0.6 for PVA and PLGA solutions. CFD simulation demonstrated the high mixing intensity of about 0.99 at optimum condition in the microfluidic system, which is the possible reason for advantageous performance of  this system. Altogether, the results of microfluidic-assisted method were found to be more reproducible, predictable, and controllable than batch method for producing a nanoformulation for delivery of drugs.

Cancer is the first cause of death in developed countries. The heterogeneous nature of cancer requires patient-specified treatment plans. One reliable approach is collecting Circulating Tumour Cells (CTCs) and using them for prognosis and drug response assessment purposes. CTCs are rare and their separation from normal cell requires high-accuracy methods.

A microfluidic cell capture device to separate CTCs from peripheral blood is presented in this study. The CTC separation device applies hydrodynamic forces to categorize cells according to their sizes. The proposed device is designed and evaluated by numerical simulations and validated experimentally. The simulation modified design was fabricated by soft lithography which allows prototyping the device in a few hours. For experimental setup two solutions: 1) fixed cells spiked in Phosphate Buffered Saline (PBS), and 2) fixed cells in blood were used. The CTC separation device was validated by tracking the flow and separation of cancer cell lines in the solutions.

It is demonstrated that the setup is capable of CTC enrichment up to 50 times.

The presented CTC enrichment method reduces costs by eliminating the use of antibodies. The high-throughput method has the potential to be used in preclinical studies of cancer.

Glaucoma is the leading cause of irreversible blindness and vision loss in the world. Although intraocular pressure (IOP) is no longer considered the only risk factor for glaucoma, it is still the most important one. In most cases, high IOP is secondary to trabecular meshwork dysfunction. High IOP leads to compaction of the lamina cribrosa and subsequent damage to retinal ganglion cell axons. Damage to the optic nerve head is evident on funduscopy as posterior bowing of the lamina cribrosa and increased cupping. Currently, the only documented method to slow or halt the progression of this disease is to decrease the IOP; hence, accurate IOP measurement is crucial not only for diagnosis, but also for the management. Due to the dynamic nature and fluctuation of the IOP, a single clinical measurement is not a reliable indicator of diurnal IOP; it requires 24‑hour monitoring methods. Technological advances in microelectromechanical systems and microfluidics provide a promising solution for the effective measurement of IOP. This paper provides a broad overview of the upcoming technologies to be used for continuous IOP monitoring.

In conventional assisted reproductive technology (ART), oocytes are cultured in static microdrops within Petri dishes that contain vast amounts of media. However, the in vivo environment is dynamic. This study assesses in vitro oocyte maturation through the use of a new microfluidic device. We evaluate oocyte fertilization to the blastocyct stage and their glutathione (GSH) contents in each experimental group.
In this experimental study, we established a dynamic culture condition. Immature oocytes were harvested from ovaries of Naval Medical Research Institute (NMRI) mice. Oocytes were randomly placed in static (passive) and dynamic (active) in vitro maturation (IVM) culture medium for 24 hours. In vitro matured oocytes underwent fertilization, after which we placed the pronucleus (PN) stage embryos in microdrops and followed their developmental stages to blastocyst formation after 3 days. GSH content of the in vitro matured oocytes was assessed by monochlorobimane (MCB) staining.
We observed significantly higher percentages of mature metaphase II oocytes (MII) in the passive and active dynamic culture systems (DCS) compared to the static group (P Dynamic culture for in vitro oocyte maturation improves their developmental competency in comparison with static culture conditions.