Learning-based automatic sensing and size classification of microparticles using smartphone holographic microscopy.

The accurate and fast size classification of microparticles is important in environmental monitoring and biomedical applications. Conventional methods for sensing and classifying microparticles require bulky optical setups and generally show medium performance. Accordingly, the development of a portable and smart platform for accurate particle size classification is essential. In this study, we propose a new sensing platform for automatic identification of microparticle types through the synergistic integration of smartphone-based digital in-line holographic microscopy (DIHM) and machine-learning algorithms. The smartphone-based DIHM system consists of a coherent laser beam, a pinhole, a sample holder, a three-dimensional printed attachment, and a modified built-in smartphone camera module. The portable device has a physical dimension of 4 × 8 × 10 cm3 and 220 g in weight. Holograms of various polystyrene microparticles with different sizes (d = 2-50 µm) were recorded with a wide field-of-view and high spatial resolution. To establish a proper classification model, tens of features including geometrical parameters and light-intensity distributions were extracted from holograms of individual particles, and five machine-learning algorithms were used. After examining the performance of several classifiers, the resulting support vector machine model trained by using three geometrical parameters and three extracted parameters from light-intensity distributions shows the highest accuracy in the particle classification of the training and test sets (>98%). Therefore, the developed handheld smartphone-based platform can be potentially utilized to cope with various imaging needs in mobile healthcare and environmental monitoring.

Pressure-driven spontaneous ion concentration polarization using an ion-selective membrane.

In this study, the spontaneous ion concentration polarization phenomenon induced by pressure via a cation-selective membrane was theoretically and experimentally investigated. Unlike conventional electrokinetic ion concentration polarization, which uses electric current as a driving flux of cations through the membrane, advection caused by pressure is used as a transmembrane driving flux of cations to spontaneously and stably form an ion depletion zone in the present ion concentration polarization technique. The ion depletion zone produced in a simple experimental setup was used to filter electrolyte and preconcentrate ions and microparticles. Different from the general assumption of the negligible thickness of the electric double layer in microchannels, the low concentration in the ion depletion zone considerably increased the length of the electric double layer. This enhanced the formation of the ion depletion zone. The present results can improve the understanding on ion transport in the ion concentration polarization system and can be utilized to develop a portable water desalination device for rural/remote areas and for preconcentrating biomolecules.

Nano-Aggregates of Doxorubicin-Conjugated Methoxy Poly(ethylene glycol)-b-Carboxymethyl Dextran Copolymer.

Block copolymer composed of carboxymethyl dextran (CMDex) and methoxy poly(ethylene glycol) (MPEG) (abbreviated as CMDexPEG) was synthesized and doxorubicin (DOX) was conjugated with carboxyl groups of CMDexPEG. DOX-conjugated CMDexPEG block copolymer formed nanoparticles in water with sizes less than 100 nm. DOX-conjugated nanoparticles enhanced DOX delivery to the DOX-resistant CT26 cells and showed higher anticancer activity in vitro. DOX-conjugated nanoparticles inhibited growth of CT26 solid tumor at tumor-bearing mouse model study. In near infrared (NIR)-dye study, nanoparticles were retained in the tumor tissues for a longer period.

Self-Organized Nanoparticles of Caffeic Acid Conjugated Polysaccharide and Its Anticancer Activity.

Caffeic acid-conjugated chitosan (ChitoCFA) and carboxymethyl dextran-b-poly(ethylene gycol) (CMD-PEG) copolymer were synthesized to fabricate self-organized nanoparticles. Nanoparticles were formed through ion-complex formation between ChitoCFA and CMD-PEG. Nanoparticles have small sizes ranged about 80 nm~300 nm with spherical shapes. Doxorubicin (DOX) was incorporated into the nanoparticles of ChitoCFA/CMD complexes. Particle sizes were increased according to the contents of drug. At drug release experiment, DOX was continuously released over 96 h. Anticancer acticity of nanoparticles were assessed with DOX-resistant CT26 cells. CT26 cells treated with DOX-incorporated nanoparticles revealed strong fluorescence intensity while free DOX revealed weak fluorescence intensity, indicating that DOX-loaded nanoparticles of ChitoCFA/CMD are promising vehicle for anticancer drug targeting.

Biomedical Applications of Magnetically Functionalized Organic/Inorganic Hybrid Nanofibers.

Nanofibers are one-dimensional nanomaterial in fiber form with diameter less than 1 µm and an aspect ratio (length/diameter) larger than 100:1. Among the different types of nanoparticle-loaded nanofiber systems, nanofibers loaded with magnetic nanoparticles have gained much attention from biomedical scientists due to a synergistic effect obtained from the unique properties of both the nanofibers and magnetic nanoparticles. These magnetic nanoparticle-encapsulated or -embedded nanofiber systems can be used not only for imaging purposes but also for therapy. In this review, we focused on recent advances in nanofibers loaded with magnetic nanoparticles, their biomedical applications, and future trends in the application of these nanofibers.

A case of acute retinal toxicity caused by an intraocular foreign body composed of cobalt alloy.

CONTEXT: We describe a case of acute retinal toxicity caused by an intraocular foreign body composed of a cobalt alloy. CASE PRESENTATION: A 36-year-old man presented to an outside clinic with a traumatic cataract and corneal laceration of his left eye, which had occurred while grinding a shelf. The lacerated cornea was closed primarily and the traumatic cataract was phacoemulsified. He was transferred to our hospital due to identification of a metallic intraocular foreign body in the vitreous. On arrival at our institution, the intraocular foreign body was removed as soon as possible after vitrectomy. On the first postoperative day, vasculitis and serous retinal detachment were observed on the retina at the previous site of the foreign body. Two months after surgery, atrophy of nearly half of the inferior retina was noted on funduscopy, and visual acuity was such that the patient could only count fingers at 30 cm. Analysis of the foreign body revealed that it was composed of 84.99% tungsten carbide, 15% cobalt and had traces of titanium and alumina. DISCUSSION: Cobalt containing metallic foreign bodies should be immediately removed, as they have the potential to cause permanent visual disturbance.

Surface tunable polymersomes loaded with magnetic contrast agent and drug for image guided cancer therapy.

Polymersomes with different surface charges were synthesized from polysuccinimide (p) by introducing positively charged polyethylenimine (PEI-P), neutrally charged polyethylene glycol (PEG-P), and negatively charged glycine (GLY-P) to the polymer backbone polysuccinimide (P). Then, the polymersomes were prepared with super paramagnetic iron nanoparticles (SPIONs) to obtain PEI-P encapsulating SPIONs (PEI-PS), PEG-P encapsulating SPIONs (PEG-PS), and GLY-P encapsulating SPIONs (GLY-PS), respectively. The average particle sizes of GLY-PS, PEG-PS, and PEI-PS were analyzed by dynamic light scattering, and it was around 163.nm, 105 nm, and 285 nm, respectively. The surface charges of GLY-PS, PEG-PS, and PEI-PS was found to be -29.5, -18.9, and +44, respectively. The presence of PEI, PEG, and GLY in the polymer backbone was confirmed with nuclear magnetic resonance (NMR). The GLY-PS, PEG-PS, and PEI-PS were loaded with the anticancer drug paclitaxel during the preparation. The drug release from the PEG-PS was faster compared to GLY-PS and PEI-PS. An in vivo hemi-spleen mouse metastatic liver model was established and imaged with MRI after intravenous administration of GLY-PS, PEG-PS, and PEI-PS. From the T2-weighted imaging, it was evident that PEG-PS accumulated in the spleen and liver more efficiently than the other charged formulations of GLY-PS and PEI-PS. From this study, the nanoparticle-based delivery and imaging of anti-cancer drugs could be effectively demonstrated simultaneously.

Extracorporeal bypass model of blood circulation for the study of microvascular hemodynamics.

Many studies have been performed to better understand the hemodynamics in microvessels, such as arterioles and venules. However, due to the heterogeneous features of size, shape, blood-flow velocity, and pulsatility of microvessels, conducting a systematic study on these factors has been almost impossible. Although in vitro studies have been performed for this purpose, the usefulness of in vitro data is limited by the fact that the rheological properties of blood are changed as blood is exposed to in vitro environments. The purpose of the present study is to investigate the feasibility of a rat extracorporeal bypass model that combines in vivo and in vitro models. An arteriovenous shunt loop with a sub-bypass loop of fluorinated ethylene propylene (FEP) microtube was constructed between the jugular vein and femoral artery of a rat. Three pinch valves were installed in the main loop. Microscopic images of the blood flow in the FEP tube were sequentially captured with a high-speed camera, and the whole velocity field information was obtained using a micro-particle image velocimetry technique. Experimental results reveal that the velocity fields of the blood flow inside the microtube are well measured because the FEP tube is transparent and has nearly the same refractive index as water. The flow velocity and the pulsatility index of the blood flow in the microtube can be controlled by adjusting the three pinch valves installed upstream, midstream, and downstream of the bypass loop. This hybrid model that combines in vivo and in vitro models can be useful in studying microvascular hemodynamics.

Aberration compensation for objective phase curvature in phase holographic microscopy.

In this study, we proposed a simple and fast numerical approach to compensate for aberrations induced by objective phase curvature. This method is based on the extraction of virtual background phase from reconstructed phase values using a line profile, followed by subtraction of the virtual background phase from the reconstructed phase image. The performance and feasibility of the method were demonstrated by applying it to the phase imaging of polystyrene microspheres and red blood cells.

Enhanced anti-cancer effect of 5-fluorouracil loaded into thermo-responsive conjugated linoleic acid-incorporated poloxamer hydrogel on metastatic colon cancer models.

Conjugated linoleic acid-coupled Pluronic F127 (Plu-CLA) is an effective drug delivery system with numerous advantages and anti-cancer activity. 5-FU administered in Plu-CLA hydrogel (P-FU) led to the significant enhancement of tumor growth suppression and cellular apoptosis. Moreover, growth of hepatic and intraperitoneal metastases in vivo was significantly reduced in mice treated with P-FU. Therefore, Plu-CLA could be a potential intraperitoneal carrier for hydrophilic 5-FU for the effective treatment of metastatic colon cancer.

Eco-friendly erucamide-polydimethylsiloxane coatings for marine anti-biofouling.

Marine biofouling of ship hulls and ocean structures causes enormous economic losses due to increased frictional drag. Thus, efforts have been exerted worldwide to eliminate biofouling. In addition, a strong demand exists for the development of a cost-effective and eco-friendly anti-biofouling coating technology. Thus, erucamide-polydimethylsiloxane (EP) coating is proposed in this study. EP exhibits a hydrophobic surface as the erucamide content and drag reduction effect increase. In this study, the drag reduction effect of the EP 2.5 is better than that of glass and polydimethylsiloxane (PDMS) surfaces. Moreover, the proposed EP coatings are observed to prevent the biofouling induced by bacteria (E. coli) and brown algae (Cladosiphon sp.). In addition, through a marine field test, the anti-biofouling effect of the EP surface is found to be better than the previously studied oleamide-PDMS (OP) surface. In the marine field test, the EP 2.5 demonstrates superior anti-biofouling performance for 5.5 months under real marine environment. The proposed eco-friendly EP coating method could be applicable to marine vehicles that require effective drag reduction and anti-biofouling properties.

Effects of N-acetylcysteine inhalation therapy on the quality of life of patients with head and neck cancer who are receiving radiation therapy: a prospective non-randomized controlled multi-center study.

BACKGROUNDS AND PURPOSE: Radiation therapy is an important mode of treatment for patients with head and neck cancers, but some associated complications can reduce the quality of life. We investigated whether N-acetylcysteine inhalation therapy improved the quality of life of such patients. MATERIALS AND METHODS: We designed a prospective, non-randomized controlled multi-center study involving 10 institutions. We enrolled 120 patients (80 in the experimental group and 40 in the control group). Patients in the experimental group inhaled nebulized liquid N-acetylcysteine (2400 mg daily) for 8 weeks from the start of radiation therapy. Quality of life was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire H&N 35. RESULTS: N-acetylcysteine inhalation was not associated with any side effect or discomfort. The reduction in painkiller use from the end of N-acetylcysteine inhalation therapy to the 1-month follow-up was greater in the experimental group than in the control group (P = 0.014). Dry mouth symptoms also improved significantly in the experimental group (P = 0.019). CONCLUSION: N-acetylcysteine inhalation improves the quality of life of patients with head and neck cancers who are receiving radiation therapy, without any specific side effect.

Membrane-electrode assembly enhances performance of a microbial fuel cell type biological oxygen demand sensor.

A membrane-electrode assembly (MEA) was applied to a microbial fuel cell (MFC) type biological oxygen demand (BOD) sensor and the performance of the sensor was assessed. To establish the optimal conditions for MEA fabrication, platinum-catalysed carbon cloth cathodic electrodes were assembled with cation exchange membranes under various temperatures and pressures. By analysing coulombs from the MFCs, it could be determined that the optimal hot-pressing conditions were 120 degrees C and 150 kg cm(-2) for 30 s. When the MEA fabricated under optimal conditions and an air cathode were utilized for the construction of the MFC type BOD sensor, coulombs increased to 4.65 C from 0.52 C and power increased to 69,080 mW m(-3) from 880 mW m(-3) (at a BOD concentration of 200 mg L(-1)), respectively, compared with the conventional MFC lacking a MEA. The increased power improved the performance of the MFC type BOD sensor: sensitivity increased from 1.2 x 10(-3) to 1.8 x 10(-2) C per mg L(-1) of BOD, with good linearity (r2 = 0.97) and over 97% repeatability. We conclude that the MEA can be successfully applied to MFCs to make them highly sensitive BOD sensors.

Air spreading through wetted cellulose membranes: Implications for the safety function of hydraulic valves in plants.

Plants transport water against the risk of cavitation inside xylem vessels, called "embolism." As one of their hydraulic strategies, pit membranes composed of cellulose fibers have been known as safety valves that prevent the spreading of embolism towards adjacent xylem vessels. However, detailed observation of embolism spreading through a pit membrane is still lacking. Here, we hypothesized that the pit membranes normally remain to be wetted in xylem vessels and noticed in particular the hydraulic role of water film on air spreading that has been overlooked previously. For the hydrodynamic study of the embolism spreading through a wetted pit membrane, we investigated the penetration and spreading dynamics of air plugs through the wetted cellulose membrane in a channel flow. Air spreading exhibits two types of dynamics: continuous and discrete spreading. We elucidated the correlation of dynamic characteristics of air flow and pressure variations according to membrane thickness. Our study speculates that the thickness of pit membranes affects the behaviors of water film captured by cellulose fibers, and it is a crucial criterion for the reversible gating of further spreading of embolism throughout xylem networks.

A Biologically-Inspired Symmetric Bidirectional Switch.

Stimuli-sensitive hydrogels have been intensively studied because of their potential applications in drug delivery, cell culture, and actuator design. Although hydrogels with directed unidirectional response, i.e. capable of bending actuated by different chemical components reaction in response to several stimuli including water and electric fields, these hydrogels are capable of being actuated in one direction only by the stimulus. By contrast the challenge of building a device that is capable of responding to the same cue (in this case a temperature gradient) to bend in either direction remains unmet. Here, inspired by the structure of pine cone scales, we design a temperature-sensitive hydrogel with bending directed an imposed fishing line. The layers with same PNIPAAm always shrinks in response to the heat. Even the layers made with different chemical property, bends away from a warm surface, whether the warm surface is applied at its upper or lower boundary. To design the bending hydrogel we exploited the coupled responses of the hydrogel; a fishing line intercalating structure and change its construction. In addition to revealing a new capability of stimulus sensitive hydrogels, our study gives insight into the structural features of pine cone bending.

Optimum periodicity of repeated contractile actions applied in mass transport.

Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications.

Detaching droplets in immiscible fluids from a solid substrate with the help of electrowetting.

The detachment (or removal) of droplets from a solid surface is an indispensable process in numerous practical applications which utilize digital microfluidics, including cell-based assay, chip cooling, and particle sampling. When a droplet that is fully stretched by impacting or electrowetting is released, the conversion of stored surface energy to kinetic energy can lead to the departure of the droplet from a solid surface. Here we firstly detach sessile droplets in immiscible fluids from a hydrophobic surface by electrowetting. The physical conditions for droplet detachment depend on droplet volume, viscosity of ambient fluid, and applied voltage. Their critical conditions are determined by exploring the retracting dynamics for a wide range of driving voltages and physical properties of fluids. The relationships between physical parameters and dynamic characteristics of retracting and jumping droplets, such as contact time and jumping height, are also established. The threshold voltage for droplet detachment in oil with high viscosity is largely reduced (~70%) by electrowetting actuations with a square pulse. To examine the applicability of three-dimensional digital microfluidic (3D-DMF) platforms to biological applications such as cell culture and cell-based assays, we demonstrate the detachment of droplets containing a mixture of human umbilical vein endothelial cells (HUVECs) and collagen (concentration of 4 × 10(4) cells mL(-1)) in silicone oil with a viscosity of 0.65 cSt. Furthermore, to complement the technical limitations due to the use of a needle electrode and to demonstrate the applicability of the 3D-DMF platform with patterned electrodes to chemical analysis and synthesis, we examine the transport, merging, mixing, and detachment of droplets with different pH values on the platform. Finally, by using DC and AC electrowetting actuations, we demonstrate the detachment of oil droplets with a very low contact angle (<~13°) in water on a hydrophobic surface.

Polysaccharide-Coated Magnetic Nanoparticles for Imaging and Gene Therapy.

Today, nanotechnology plays a vital role in biomedical applications, especially for the diagnosis and treatment of various diseases. Among the many different types of fabricated nanoparticles, magnetic metal oxide nanoparticles stand out as unique and useful tools for biomedical applications, because of their imaging characteristics and therapeutic properties such as drug and gene carriers. Polymer-coated magnetic particles are currently of particular interest to investigators in the fields of nanobiomedicine and fundamental biomaterials. Theranostic magnetic nanoparticles that are encapsulated or coated with polymers not only exhibit imaging properties in response to stimuli, but also can efficiently deliver various drugs and therapeutic genes. Even though a large number of polymer-coated magnetic nanoparticles have been fabricated over the last decade, most of these have only been used for imaging purposes. The focus of this review is on polysaccharide-coated magnetic nanoparticles used for imaging and gene delivery.

Poly(PEGA)-b-poly(L-lysine)-b-poly(L-histidine) Hybrid Vesicles for Tumoral pH-Triggered Intracellular Delivery of Doxorubicin Hydrochloride.

A series of poly(ethylene glycol) methyl ether acrylate-block-poly(L-lysine)-block-poly(L-histidine) [p(PEGA)30-b-p(Lys)25-b-p(His)n] (n = 25, 50, 75, 100) triblock copolypeptides were designed and synthesized for tumoral pH-responsive intracellular release of anticancer drug doxorubicin hydrochloride (Dox). The tumoral acidic pH-responsive hybrid vesicles fabricated were stable at physiological pH 7.4 and could gradually destabilize in acidic pH as a result of pH-induced swelling of the p(His) block. The blank vesicles were nontoxic over a wide concentration range (0.01-100 µg/mL) in normal cell lines. The tumor acidic pH responsiveness of these vesicles was exploited for intracellular delivery of Dox. Vesicles efficiently encapsulated Dox, and pH-induced destabilization resulted in the controlled and sustained release of Dox in CT26 murine cancer cells, and dose-dependent cytotoxicity. The tumor-specific controlled release Dox from vesicles demonstrates this system represents a promising theranostic agent for tumor-targeted delivery.