Chaobo Huang

Stimuli-responsive electrospun fibers and their applications

Stimuli-responsive electrospun nanofibers are gaining considerable attention as highly versatile tools which offer great potential in the biomedical field. In this critical review, an overview is given on recent advances made in the development and application of stimuli-responsive fibers. The specific features of these electrospun fibers are highlighted and discussed in view of the properties required for the diverse applications. Furthermore, several novel biomedical applications are discussed and the respective advantages and shortcomings inherent to stimuli-responsive electrospun fibers are addressed (136 references).

Electrospun cellulose acetate phthalate fibers for semen induced anti-HIV vaginal drug delivery

Despite many advances in modern medicine, human immunodeficiency virus (HIV) still affects the health of millions of people world-wide and much effort is put in developing methods to either prevent infection or to eradicate the virus after infection has occurred. Here, we describe the potential use of electrospun cellulose acetate phthalate (CAP) fibers as a tool to prevent HIV transmission. During the electrospinning process, anti-viral drugs can easily be incorporated in CAP fibers. Interestingly, as a result of the pH-dependent solubility of CAP, the fibers are stable in vaginal fluid (the healthy vaginal flora has a pH of below 4.5), whereas the addition of small amounts of human semen (pH between 7.4 and 8.4) immediately dissolves the fibers which results in the release of the encapsulated drugs. The pH-dependent release properties have been carefully studied and we show that the released anti-viral drugs, together with the CAP which has been reported to have intrinsic antimicrobial activity, efficiently neutralize HIV in vitro.

Electrospun fibers for oil–water separation

The increasing worldwide oil pollution intensifies the needs for new techniques of separation of oil from oily water. Separation by the use of electrospun fibers with selective oil/water absorption is a relatively new but highly promising technique. Owing to their highly specific surface areas, interconnected nanoscale pore structures and the potential to incorporate active chemistry on a nanoscale surface, electrospun fibers have become a promising versatile platform for the separation of oil/water mixtures and emulsions. In this review, after a short introduction to the imperative for oil/water separation and electrospinning technique, we will focus on superhydrophobic/superoleophilic electrospun fibers for oil/water separation, including the preparation of electrospun fibers with superhydrophobic/superoleophilic surfaces, and superhydrophobic/superoleophilic fibrous membranes for oil absorption and oil filtration. Further, superoleophobic/superhydrophilic electrospun fibers and their application for oil–water separation will be discussed as well. Finally, conclusions about this review will be presented while addressing remaining problems and future challenges.

Unbreakable Codes in Electrospun Fibers: Digitally Encoded Polymers to Stop Medicine Counterfeiting

Fluorescent polymer solutions can easily be electrospun into micrometer-sized fibers and subsequently encoded with long lasting digital codes by a photobleaching process. Such encoded fibers may find various applications; as illustrated in this report, placing encoded fibers in drug tablets may become a strategy to protect them from counterfeiting.

Core–sheath structured electrospun nanofibrous membranes for oil–water separation

In recent years, both the increasing frequency of oil spill accidents and the urgency to deal seriously with industrial oil-polluted water, encouraged material scientists to design highly efficient, cost effective oil–water separation technologies. We report on electrospun nanofibrous membranes which are composed of core–sheath structured cellulose-acetate (CA)–polyimide (PI) nanofibers. On the surface of the CA–PI fibers a fluorinated polybenzoxazine (F-PBZ) functional layer, in which silica nanoparticles (SNPs) were incorporated, has been applied. Compared with F-PBZ/SNP modified CA fibers reported before for the separation of oil from water, the PI-core of the core–shell F-PBZ/SNP/CA–PI fibers makes the membranes much stronger, being a significant asset in their use. Nanofibrous membranes with a tensile strength higher than 200 MPa, a high water contact angle of 160° and an extremely low oil contact angle of 0° were obtained. F-PBZ/SNP/CA–PI membranes seemed very suitable for gravity-driven oil–water separation as fast and efficient separation (>99%) of oil from water was achieved for various oil–water mixtures. The designed core–sheath structured electrospun nanofibrous membranes may become interesting materials for the treatment of industrial oil-polluted water.

Effective method of chitosan-coated alginate nanoparticles for target drug delivery applications.

In the present study, alginate nanoparticles were firstly prepared for paclitaxel (PTX) delivery with an average size of 200 ± 21 nm. To improve the stability and targeting effect, the chitosan (CS) and folate-chitosan (FA-CS) were introduced to form PTX-loaded CS/ALG NPs and FA-CS/ALG NPs by a new double emulsion cross-linking electrostatic attraction method. The optimization chitosan concentration was 0.5% obtained from the experiment results. The CS/ALG-PTX NPs and FA-CS/ALG-PTX NPs had the average particle size of 306.9 ± 12.9 nm and 283.6 ± 19.2 nm with the zeta potential of 31.1 ± 1.3 mV and −2.98 ± 0.7 mV, and had higher drug loading and entrapment efficiencies than ALG-PTX NPs. The in vitro drug release profile along with release kinetics and mechanism from PTX-loaded NPs were studied under two simulated physiological conditions. Further, the in vitro anti-cancer activity of nanoparticles and the cellular uptake of nanoparticles on HepG2 cells were investigated. The results demonstrated that alginate, CS/ALG and FA-CS/ALG can be used as nanoformulation drug carriers by our new method, and FA-CS/ALG was a promising vehicle for anticancer drug targeted delivery system.

Synthesis and in vitro cytotoxic evaluation of new 1H-benzo[d]imidazole derivatives of dehydroabietic acid

A series of new 1H-benzo[d]imidazole derivatives of dehydroabietic acid were designed and synthesized as potent antitumor agents. Structures of the target molecules were characterized using MS, IR, 1H NMR, 13C NMR and elemental analyses. In the in vitro cytotoxic assay, most compounds showed significant cytotoxic activities against two hepatocarcinoma cells (SMMC-7721 and HepG2) and reduced cytotoxicity against noncancerous human hepatocyte (LO2). Among them, compound 7b exhibited the best cytotoxicity against SMMC-7721 cells (IC50: 0.36±0.13μM), while 7e was most potent to HepG2 cells (IC50: 0.12±0.03μM). The cell cycle analysis indicated that compound 7b caused cell cycle arrest of SMMC-7721 cells at G2/M phase. Further, compound 7b also induced the apoptosis of SMMC-7721 cells in Annexin V-APC/7-AAD binding assay.

Development of a method for the measurement of primary cilia length in 3D

BackgroundPrimary cilia length is an important measure of cell and tissue function. While accurate length measurements can be calculated from cells in 2D culture, measurements in tissue or 3D culture are inherently difficult due to optical distortions. This study uses a novel combination of image processing techniques to rectify optical distortions and accurately measure cilia length from 3D images.MethodsPoint spread functions and experimental resolutions were calculated from subresolution microspheres embedded in 3D agarose gels for both wide-field fluorescence and confocal laser scanning microscopes. The degree of axial smearing and spherical aberration was calculated from xy:xz diameter ratios of 3D image data sets of 4 μm microspheres that had undergone deconvolution and/or Gaussian blurring. Custom-made 18 and 50 μm fluorescent microfibers were also used as calibration objects to test the suitability of processed image sets for 3D skeletonization. Microfiber length in 2D was first measured to establish an original population mean. Fibers were then embedded in 3D agarose gels to act as ciliary models. 3D image sets of microfibers underwent deconvolution and Gaussian blurring. Length measurements within 1 standard deviation of the original 2D population mean were deemed accurate. Finally, the combined method of deconvolution, Gaussian blurring and skeletonization was compared to previously published methods using images of immunofluorescently labeled renal and chondrocyte primary cilia.ResultsDeconvolution significantly improved contrast and resolution but did not restore the xy:xz diameter ratio (0.80). Only the additional step of Gaussian blurring equalized xy and xz resolutions and yielded a diameter ratio of 1.02. Following image processing, skeletonization successfully estimated microfiber boundaries and allowed reliable and repeatable measurement of fiber lengths in 3D. We also found that the previously published method of calculating length from 2D maximum projection images significantly underestimated ciliary length.ConclusionsThis study used commercial and public domain image processing software to rectify a long-standing problem of 3D microscopy. We have shown that a combination of deconvolution and Gaussian blurring rectifies optical distortions inherent in 3D images and allows accurate skeletonization and length measurement of microfibers and primary cilia that are bent or curved in 3D space.

A label-free and turn-on fluorescence sensor for sensitive and selective detection of iodide using carbon nanodots/silver nanocomposites

Based on the principle of fluorescence recovery, by the strong and specific interaction between iodide (I−) ions and nanoAg on the surface of carbon nanodots/silver (Cdots/Ag) nanocomposites, we propose a simple label-free and turn-on method for the detection of I− ions with high selectivity and sensitivity by using fluorescent Cdots/Ag nanocomposites in aqueous media.

Microfluidic chip for monitoring Ca2+ transport through a confluent layer of intestinal cells

The absorption of dietary calcium through the intestinal barrier is essential for maintaining health in general and especially of the bone system. We propose a microfluidic model that studies free calcium (Ca2+) transport through a confluent monolayer of Caco-2 cells. The latter were cultured on a porous membrane that was positioned in between a top and bottom microfluidic chamber. Fresh cell culture medium was continuously supplied into the device at a flow rate of 5 nL s−1 and the culture progress of the cell monolayer was continuously monitored using integrated Transepithelial Electrical Resistance (TEER) electrodes. The electrical measurements showed that the Caco-2 monolayer formed a dense and tight barrier in 5 days. The transported free Ca2+ from the top microfluidic chamber to the basolateral side of the cell monolayer was measured using the calcium-sensitive dye fura-2. This is a ratiometric dye which exhibits an excitation spectrum shift from 340 nm to 380 nm, when it binds to Ca2+ with an emission peak at 510 nm. Therefore, the concentration of free Ca2+ is proportional to the ratio of fluorescence emissions obtained by exciting at 340 nm and 380 nm. The barrier function of the cell monolayer was evaluated by a measured rate of Ca2+ transport through the monolayer that was 5 times lower than that through the bare porous membrane. The continuous perfusion of cell nutrients and the resultant mechanical shear on the cell surface due to the fluid flow are two key factors that would narrow the gap between the in vivo and in vitro conditions. These conditions significantly enhance the Caco-2 cell culture model for studying nutrients bioavailability.