Cellulose nanocrystal hydrogels, while mechanically weak, have high water content, are biocompatible and easily processed. Further improvement is needed to make cellulose nanocrystal hydrogels ...mechanically stable and self-healable. Herein, using quantitative fluorescence signal analysis, we assess stability, collapse, and level of self-healing of cellulose nanocrystal hydrogels with different cellulose nanocrystals and sodium chloride concentrations. We use the mean signal intensity obtained by confocal laser scanning microscopy to measure signal loss of the samples made of cellulose nanocrystal with different concentrations and as a function of initial gel height and sodium chloride loading. The cellulose nanocrystal dynamics inside the gels based on universality curve is unraveled which links the zeta potentials to the immobile particle percentages and the storage modulus as a function of sodium chloride/cellulose nanocrystal concentration ratio. Fluorescence recovery after photobleaching recovery analysis shows that for the ratio of sodium chloride/cellulose nanocrystals beyond 0.1, the mobility of the ensemble of cellulose nanocrystals particles becomes severely restricted. Hydrogel sample with low cellulose nanocrystal concentrations (6 g/L and 10 g/L) experience a more substantial collapse rate under gravity than the rate observed for samples with a high concentration (30 g/L). Increasing the cellulose nanocrystal concentration hinders particle mobility and thus impedes the self-healing process. Quantification of the gel collapse behavior of cellulose nanocrystal gel and its self-healing property is critical in many applications, including water and air filters, oil spill sponges, and tissue engineering.
Graphic abstract
In this paper, a simple practical method is presented to fabricate a high aspect ratio horizontal polydimethylsiloxane (PDMS) microcantilever-based flow sensor integrated into a microfluidic device. ...A multilayer soft lithography process is developed to fabricate a thin PDMS layer involving the PDMS microcantilever and the microfluidics network. A three-layer fabrication technique is explored for the integration of the microflow meter. The upper and lower PDMS layers are bonded to the thin layer to release the microcantilever for free deflection. A 3-D finite element analysis is carried out to simulate fluid-structure interaction and estimate cantilever deflection under various flow conditions. The dynamic range of flow rates that is detectable using the flow sensor is assessed by both simulation and experimental methods and compared. Limited by the accuracy of the 1.76- μm resolution of the image acquisition method, the present setup allows for flow rates as low as 35 μL/min to be detected. This is equal to 0.8-μN resolution in equivalent force at the tip. This flow meter can be integrated into any type of microfluidic-based lab-on-a-chip in which flow measurement is crucial, such as flow cytometry and particle separation applications.
We present a highly sensitive and selective nano-biosensor for rapid, stable and highly reproducible detection of ascorbic acid (AA) in the presence of dopamine, uric acid and other interferences by ...a three-layer sandwich arrangement of nitrogen-doped functionalized graphene (NFG), silver nanoparticles (AgNPs) and nanostructured polyaniline (PANI) nanocomposite. The enhanced AA electrochemical properties of the NFG/AgNPs/PANI electrode is attributed to the superior conductivity of the NFG-PANI and the excellent catalytic activity of AgNPs. The critical modification of the AgNPs-grafted NFG-PANI coated on very low-cost fluorine doped tin oxide electrode (FTOE) increased the charge transfer conductivity of the electrode (the resistance drops down from 11,000 Ω to 6 Ω). The nano-biosensor was used to accurately detect AA in vitamin C tablets with the recovery of 98%. The sensor demonstrated a low detection limit of 8 µM (S/N = 3) with a very wide linear detection range of 10-11,460 µM, good reproducibility and excellent selectivity performance for AA detection. The results demonstrate that this nanocomposite is a promising candidate for rapid and selective detection of AA in practical clinical samples.
The widespread accessibility of commercial/clinically‐viable electrochemical diagnostic systems for rapid quantification of viral proteins demands translational/preclinical investigations. Here, ...Covid‐Sense (CoVSense) antigen testing platform; an all‐in‐one electrochemical nano‐immunosensor for sample‐to‐result, self‐validated, and accurate quantification of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) nucleocapsid (N)‐proteins in clinical examinations is developed. The platform's sensing strips benefit from a highly‐sensitive, nanostructured surface, created through the incorporation of carboxyl‐functionalized graphene nanosheets, and poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) conductive polymers, enhancing the overall conductivity of the system. The nanoengineered surface chemistry allows for compatible direct assembly of bioreceptor molecules. CoVSense offers an inexpensive (<$2 kit) and fast/digital response (<10 min), measured using a customized hand‐held reader (<$25), enabling data‐driven outbreak management. The sensor shows 95% clinical sensitivity and 100% specificity (Ct<25), and overall sensitivity of 91% for combined symptomatic/asymptomatic cohort with wildtype SARS‐CoV‐2 or B.1.1.7 variant (N = 105, nasal/throat samples). The sensor correlates the N‐protein levels to viral load, detecting high Ct values of ≈35, with no sample preparation steps, while outperforming the commercial rapid antigen tests. The current translational technology fills the gap in the workflow of rapid, point‐of‐care, and accurate diagnosis of COVID‐19.
Covid‐Sense
(CoVSense) utilizes electrochemical immunosensing technology for rapid and quantitative detection of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) viruses in clinical nasal specimens obtained from all‐inclusive cohort of patients, offering favorable features in terms of accuracy, signal correlation with viral load, and digital data management, compared to gold standard techniques, such as polymerase chain reaction and lateral flow strips.
Primary bronchial cancer accounts for almost 20% of all cancer death worldwide. One of the emerging techniques with tremendous power for lung cancer therapy is magnetic aerosol drug targeting (MADT). ...The use of a permanent magnet for effective drug delivery in a desired location throughout the lung requires extensive optimization, but it has not been addressed yet. In the present study, the possibility of using a permanent magnet for trapping the particles on a lung tumor is evaluated numerically in the Weibel's model from G0 to G3. The effect of different parameters is considered on the efficiency of particle deposition in a tumor located on a distant position of the lung bronchi and bronchioles. Also, the effective position of the magnetic source, tumor size, and location are the objectives for particle deposition. The results show that a limited particle deposition occurs on the lung branches in passive targeting. However, the incorporation of a permanent magnet next to the tumor enhanced the particle deposition fraction on G2 to up to 49% for the particles of 7 µm diameter. Optimizing the magnet size could also improve the particle deposition fraction by 68%. It was also shown that the utilization of MADT is essential for effective drug delivery to the tumors located on the lower wall of airway branches given the dominance of the air velocity and resultant drag force in this region. The results demonstrated the high competence and necessity of MADT as a noninvasive drug delivery method for lung cancer therapy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Miniaturization of liquid chromatography (LC) is at the leading edge of the research topics and offers a wide range of applications in chemistry, biology, pharmaceutical, clinical diagnosis, and food ...analysis. The state-of-the-art “lab-on-chip” or “micro-total analysis systems” gathered scientists all over the world to provide systems with the aim of portability, reliability, reduced analysis time and cost of operation and analysis. From the hardware equipment point of view, the LC system is made by the primary compartments of solvent reservoir, pump, injector, column, and detector. In this work, we surveyed the development of LC systems and advances in each of the integrated components (i.e. pumping systems, injectors, separation channels, and detector) and the materials used for their fabrication from the beginning up to now. Finally, we summarize the application of fully integrated LC systems and exemplify about the multidimensional LCs on a chip development.
•The development of liquid chromatography (LC) on a chip is investigated from the beginning up to now.•The role and features of main parts of LCs on a chip is demonstrated in details.•Different forces and theories for pumping systems and injection methods on a chip are discussed.•Different types of stationary phases and the separation channels' geometries are investigated.•The study of fully integrated LCs, commercial chip-based LCs and application of them in life science is surveyed.
Microcontact printing (μCP) of proteins is widely used for biosensors and cell biology but is constrained to printing proteins adsorbed to a low free energy, hydrophobic surface to a high free ...energy, hydrophilic surface. This strongly limits μCP as harsh chemical treatments are required to form a high energy surface. Here, we introduce humidified μCP (HμCP) of proteins which enables universal printing of protein on any smooth surface. We found that by flowing water in proximity to proteins adsorbed on a hydrophilized stamp, the water vapor diffusing through the stamp enables the printing of proteins on both low and high energy surfaces. Indeed, when proteins are printed using stamps with increasing spacing between water-filled microchannels, only proteins adjacent to the channels are transferred. The vapor transport through the stamp was modeled, and by comparing the humidity profiles with the protein patterns, 88% relative humidity in the stamp was identified as the threshold for HμCP. The molecular forces occurring between PDMS, peptides, and glass during printing were modeled ab initio to confirm the critical role water plays in the transfer. Using HμCP, we introduce straightforward protocols to pattern multiple proteins side-by-side down to nanometer resolution without the need for expensive mask aligners, but instead exploiting self-alignment effects derived from the stamp geometry. Finally, we introduce vascularized HμCP stamps with embedded microchannels that allow printing proteins as arbitrary, large areas patterns with nanometer resolution. This work introduces the general concept of water-assisted μCP and opens new possibilities for “solvent-assisted” printing of proteins and of other nanoparticles.
Emerging evidence shows that endothelial cells are not only the building blocks of vascular networks that enable oxygen and nutrient delivery throughout a tissue but also serve as a rich resource of ...angiocrine factors. Endothelial cells play key roles in determining cancer progression and response to anti-cancer drugs. Furthermore, the endothelium-specific deposition of extracellular matrix is a key modulator of the availability of angiocrine factors to both stromal and cancer cells. Considering tumor vascular network as a decisive factor in cancer pathogenesis and treatment response, these networks need to be an inseparable component of cancer models. Both computational and in vitro experimental models have been extensively developed to model tumor-endothelium interactions. While informative, they have been developed in different communities and do not yet represent a comprehensive platform. In this review, we overview the necessity of incorporating vascular networks for both in vitro and in silico cancer models and discuss recent progresses and challenges of in vitro experimental microfluidic cancer vasculature-on-chip systems and their in silico counterparts. We further highlight how these two approaches can merge together with the aim of presenting a predictive combinatorial platform for studying cancer pathogenesis and testing the efficacy of single or multi-drug therapeutics for cancer treatment.
Microinjection is an effective actuation technique used for precise delivery of molecules and cells into droplets or controlled delivery of genes, molecules, proteins, and viruses into single cells. ...Several microinjection techniques have been developed for actuating droplets and cells. However, they are still time-consuming, have shown limited success, and are not compatible with the needs of high-throughput (HT) serial microinjection. We present a new passive microinjection technique relying on pressure-driven fluid flow and pulsative flow patterns within an HT droplet microfluidic system to produce serial droplets and manage rapid and highly controlled microinjection into droplets. A microneedle is secured within the injection station to confine droplets during the microinjection. The confinement of droplets on the injection station prevents their movement or deformation during the injection process. Three-dimensional (3D) computational analysis is developed and validated to model the dynamics of multiphase flows during the emulsion generation. We investigate the influence of pulsative flows, microneedle parameters and synchronization on the efficacy of microinjection. Finally, the feasibility of implementing our microinjection model is examined experimentally. This technique can be used for tissue engineering, cells actuation and drug discovery as well as developing new strategies for drug delivery.
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