Polymeric Devices Research Articles

Finite element modelling of non-faradic electric impedance spectroscopy through flexible polymer microchip

Numerical simulations using finite element method were performed for a better understanding of non-faradic electric impedance response of microfluidic device with two insulated planar-microband electrodes i.e. electrodes without direct contact with electrolyte flowing in the microchannel. The results showed that calculated electric impedance depends not only on the microchannel geometry and dielectric properties of electrolyte flowing in microchannel, but also on the dielectric response of the insulated PET layer. It was pointed out that a microfluidic device with insulated microelectrodes behaves as a dielectric device, in which a strong capacitive coupling effect takes place in the high-frequency domain. An analytical expression that allows predicting the optimal frequency range to be used for measuring real-time contactless microchannel resistance changes was proposed. This non-faradic impedance spectroscopy appears to be a promising approach for the new generation of sensors and biosensors in miniaturized flexible or patch polymer devices.

Polymer-based microfluidic chips for isothermal amplification of nucleic acids

Creation of low-cost compact devices based on microfluidic platforms for biological and medical research depends on the degree of development and enhancement of prototyping technologies. Two designs of polymer and hybrid microfluidic devices fabricated by soft lithography and intended for isothermal amplification and polymerase chain reaction are presented in this paper. The digital helicase-dependent isothermal amplification was tested in the device containing a droplet generator. Polymerase chain reaction was carried out in the hybrid microfluidic device having ten reaction chambers. A synthesized cDNA fragment of GAPDH housekeeping gene was used as a target.

Electric field activated nonlinear and disorder-induced charge transport in doped polymer devices

Abstract In the present study, temperature dependent conductivity and field dependent nonlinear transport are adopted to provide insight into the charge transport in poly(3-methylthiophene) polymer thin film devices that are electropolymerized at different temperatures. The samples obtained at different temperature show relative disorder quantified by the conductivity ratio, σr = σ (84 K)/σ (300 K) which is further correlated with the morphology of the samples. Charge transport in each sample is governed by variable range hopping mechanism and the parameters like density of states at the Fermi level [N(EF)], average hopping distance (R) and average hopping energy (W) have been estimated. Electric field activated nonlinear transport is described by multistep tunneling model of Glazman-Matveev (GM model) over four separate channels of conduction. It is concluded that the field dependent conductivity has a ‘field-scale’ in all the samples where the conductivity converges to a single master curve in the temperature range of observation. The results obtained from the conductivity ratio and temperature dependent conductivity are strongly supported by electric field dependent conductivity and nonlinear exponents.

Charge transport mechanism in p-type copper ion containing triazine thiolate metallopolymer thin film devices

The charge transport mechanism in copper ions containing 1,3,5-Triazine-2,4,6-trithiolate (CuTCA) based polymer device in sandwich (Ag/CuTCA/Cu) geometry is studied. The current-voltage (I-V) characteristics of the metallopolymer CuTCA device have shown a transition in the charge transport mechanism from Ohmic to Space-charge limited conduction when temperature and voltage are varied. The carriers in CuTCA devices exhibit hopping transport, in which carriers hop from one site to the other. The hole mobility in this polymer device is found to be dependent on electric field E (μpαE) and temperature, which suggests that the polymer has inherent disorder. The electric-field coefficient γ and zero-field mobility μ0 are temperature dependent. The values of mobility and activation energies are estimated from temperature (90–140 K) dependent charge transport studies and found to be in the range of 1 × 10−11–8 × 10−12 m2/(V s) and 16.5 meV, respectively. Temperature dependent electric-field coefficient γ is in the order of 17.8 × 10−4 (m/V)1/2, and the value of zero-field mobility μ0 is in the order of 1.2 × 10−11 m2/(V s) at 140 K. A constant phase element (Q) is used to model the device parameters, which are extracted using the Impedance spectroscopy technique. The bandgap of the polymer is estimated to be 2.6 eV from UV-Vis reflectance spectra.

Flexible and disposable paper- and plastic-based gel micropads for nematode handling, imaging, and chemical testing.

Today, the area of point-of-care diagnostics is synonymous with paper microfluidics where cheap, disposable, and on-the-spot detection toolkits are being developed for a variety of chemical tests. In this work, we present a novel application of microfluidic paper-based analytical devices (μPADs) to study the behavior of a small model nematode, Caenorhabditis elegans. We describe schemes of μPAD fabrication on paper and plastic substrates where membranes are created in agarose and Pluronic gel. Methods are demonstrated for loading, visualizing, and transferring single and multiple nematodes. Using an anthelmintic drug, levamisole, we show that chemical testing on C. elegans is easily performed because of the open device structure. A custom program is written to automatically recognize individual worms on the μPADs and extract locomotion parameters in real-time. The combination of μPADs and the nematode tracking program provides a relatively low-cost, simple-to-fabricate imaging and screening assay (compared to standard agarose plates or polymeric microfluidic devices) for non-microfluidic, nematode laboratories.

Modifications of Hydroxyl-Functionalized HEA/HEMA and Their Polymers in the Synthesis of Functional and Graft Copolymers

Background: Functional groups have played a fundamental role in synthesis of polymers due to they decide about polymerization methods, and influence on their topologies, properties and applications. The functional polymers are used as a high-performance materials with well-adjusted properties by modification of functionalities that can be addressed selectively to a variety of applications, usually in biomedical field. Objective: In this minireview article hydroxy-functionalized polymers, mostly based on 2-hydroxyethyl methacrylate (HEMA) or 2-hydroxyethyl acrylate (HEA), are discussed as products of the controlled polymerizations and as substrates in the functionalization reactions. Conclusion: The hydroxyl group gives opportunity for prepolymerization reactions, including protection group and macromonomer preparation. Multifunctional (co)polymers of HEMA/HEA contain reactive hydroxyl groups, which are directly accessible or caring suitable protective groups that can be removed or/and modified by post-polymerization reactions. The variation of approaches let to obtain functional polymers with linear, star-shape and graft topologies as the well-defined structures for the advanced functional materials, including smart polymeric devices.

Integration of Semiconductor Nanowire Lasers with Polymeric Waveguide Devices on a Mechanically Flexible Substrate.

Nanowire lasers are integrated with planar waveguide devices using a high positional accuracy microtransfer printing technique. Direct nanowire to waveguide coupling is demonstrated, with coupling losses as low as -17 dB, dominated by mode mismatch between the structures. Coupling is achieved using both end-fire coupling into a waveguide facet, and from nanowire lasers printed directly onto the top surface of the waveguide. In-waveguide peak powers up to 11.8 μW are demonstrated. Basic photonic integrated circuit functions such as power splitting and wavelength multiplexing are presented. Finally, devices are fabricated on a mechanically flexible substrate to demonstrate robust coupling between the on-chip laser source and waveguides under significant deformation of the system.

Making fillable, injectable polymer microparticles

Three-dimensional printing is a powerful technique for rapid prototyping, but when put into practical use, the approach may not be compatible with materials used for biomedical applications such as drug delivery. Robert S. Langer, Ana Jaklenec, and coworkers at Massachusetts Institute of Technology have developed an alternative method for making microdevices from biomedically relevant materials, such as poly(lactic-co-glycolic acid) (Science 2017, DOI: 10.1126/science.aaf7447). The researchers use polydimethylsiloxane molds to shape individual layers of multilayer polymeric devices. They then align, assemble, and bond the layers using heat. The MIT team used the method to make fillable polymer microparticles that release their contents according to a preprogrammed schedule on the basis of polymer composition. They built particle bases, filled them with drug solution, capped the bases with polymer lids, sealed them by heating, and then scraped the microparticles off the substrate. In a test application, th...

Direct bonding of polymer/glass-based microfluidic chips with dry film photoresist

Dry film has been widely used as a low-cost photoresist in the print circuit board industry which consists of a thin layer of photoresist sandwiched between two protective polymer layers. In this research, a simple, cleanroom-free, low-cost and highly adaptable bonding method for various polymer and glass-based microfluidic systems was proposed using the cross-linked dry film photoresist. In this proposed approach, the uncross-linked dry film photoresist was sandwiched between substrates and cover plate, then using UV exposure for the crosslinking of the photoresist to reach a secured bonding, after bonding, a cleaning process for the removal of photoresist residuals trapped inside the microchannels was also applied. The proposed bonding method is highly adaptable for different kinds of polymer or glass-based microfluidic devices, even the hybrid bonding between polymer and glass substrates could be achieved, which is usually very challenging using the conventional bonding technologies. Comparing with the traditional adhesive bonding method, the proposed method is simple, low-cost and without the requirement for toxic organic solvents, in addition, the cleaning procedure proposed in this study could effectively remove the residual of the adhesives trapped in the microchannels.

Electron-transport polymeric gold nanoparticles memory device, artificial synapse for neuromorphic applications

Abstract In this paper, we demonstrate the charge storage in nanoparticles “NPs” organic memory field-effect transistor using an electron-transport polymeric semiconductor layer, poly{[N,N0-bis(2-octyldodecyl)-naphthalene-1,4,5,8-is(dicarboximide)-2,6-diyl]- alt - 5,50-(2,20-bithiophene)} [P(NDI2OD-T2)n], known as its commercial name PolyeraTM N2200. The device exhibited good programmable memory characteristics with respect to the program/erase operations, leading to a reversible threshold voltage (Vth) shifts. Results revealed that OFET based NPs exhibited larger hysteresis and showed a facilitating and a depressing drain current mimicking the behavior of biological synapses, the building block responsible of action potentials transmission between neurons.

Development of Novel Orthopaedic Materials

New materials have played a critical role in Orthopaedic for many decades. Early total joints and trauma devices were made from stainless steel then titanium and cobalt-chrome replaced stainless steel in most modern implants. In addition to high-strength structural metals, polymers such as polyethylene were used for many decades in total joints followed by polyether-ether-ketone (PEEK) in spine fusion and then in sports medicine anchors. Biodegradable polymers have also made a strong impact with their beginnings in degradable sutures and current widespread use as an anchoring material in sports medicine reconstructions. This issue covers recent material developments in multiple areas of Orthopaedic surgery, such as soft-tissue fixation, hip arthroplasty, spine fusion, and wound healing. As the title suggests, orthopaedic materials may come from two avenues, emerging into the field or evolving within the field of orthopaedic surgery. Emerging materials may have a long history in other fields of medicine, but are experiencing a transition into orthopaedic use. In contrast, evolving materials have an established history in the field of orthopaedic materials, but they are being processed in new ways to gain additional functionalities. This issue will explore both of these approaches and discuss how financial and regulatory burdens affect material technology development. A recent special issue has focused on the 3-dimensional printing of materials for orthopaedics so we will not discuss that innovation here. Dr Elsner and Dr McKeon have provided a thorough review on the use of polycarbonate urethanes, a material emerging from the cardiovascular field due to its enhanced oxidative stability compared with prior polyurethanes. Regarding orthopedic use, polycarbonate urethanes show a much softer response and less wear compared with ultra-high molecular weight polyethylene, thus this material is potentially replacing bearing surfaces in hip arthroplasty and being trialed as a meniscus replacement. This review covers the full spectrum of material development from in vitro biomechanics to animal testing to clinical outcomes. Dr Smith and colleagues describe the use of shape-memory polymers for soft-tissue fixation. The concept and use of shape-memory polymers has seen a long history since the 1960s as heat-shrink tubing, but only recently have they emerged into the Orthopaedic field due to advances in activation mechanisms. The principles of both shape-memory polymers and soft-tissue fixation mechanics are discussed as well as the advantages of these expandable devices. In addition, Dr Higgs gives an in-depth explanation of how to use shape-memory polymer devices for posterior lateral corner reconstruction, which greatly simplifies the procedure. Dr Lei and colleagues have written a comprehensive review on the use of dehydrated human amnion/chorion membranes allograft for healing Orthopaedic soft-tissues. Although amniotic membranes have been used for wound healing and skin grafting since the early 20th century, it is the refinement of processing methods and continued expansion into more Orthopaedic applications that drives the use of this regenerative technology. This review covers the relevant biological markers and components of these allografts along with a myriad of clinical uses, including rotator cuff repair, anterior cruciate ligament reconstruction, Achilles tendinopathy, plantar fasciitis, and even transforaminal lumbar interbody fusion. Torstrick and colleagues discuss the development of a porous PEEK interbody fusion device. PEEK interbody fusion devices have a history of producing a fibrous tissue response due to their smooth surface, but porous PEEK challenges this paradigm with its 3-dimensional topography that allows for osseointegration. Although the effect of chemical structure and topography on osseointegration is a current debate, this porous PEEK serves as an example of how altering topography can change the biological response to a well-known material. Dr Burkus and Dr Chappuis present clinical examples of their experience where the porous PEEK interbody fusion device was used for anterior cervical discectomy and fusion. Dr Bariteau and colleagues give a detailed review of the ethical, financial, and regulatory issues to be considered when developing a new orthopedic technology. The need for new technology is illustrated by the development of total hip arthroplasty devices throughout the 20th century. Innovation is necessary for improving patient care, and it must be done in the face of steep research and development costs and significant regulatory requirements. In addition, total ankle replacements are given as an example of recent technology development in the foot and ankle market. Finally, we would like to thank all of the authors for their time and contributions to this symposium.

Fluorinated Benzothienoisoindigo Copolymers for Organic Solar Cells: A Comparative Study on Polymer Orientation and Device Performance

We report the synthesis and characterization of a new conjugated polymer composed of fluorinated benzothienoisoindigo (F-BTIDG) and benzobisthiazole (BBTz). The fluorination brought about a significant change in the crystallinity and orientation of the polymer, which results in unfavorable decrease in power conversion efficiency (ca. 1.6%). We discuss Herman’s orientation parameters, unsymmetry of the unit, and planarity of the polymer backbone based on density functional theory. The work suggests that fluorination does not always lead to improvements in polymer orientation and device performance.

Combining stereolithography and replica molding: On the way to superhydrophobic polymeric devices for photovoltaics

A strategy combining stereolithography (SL) and soft-lithography for the straightforward fabrication of superhydrophobic bulk devices is reported. Microtextured masters are rapidly prototyped by SL and passivated with a perfluorosilane. Such surface treatment enables the faultless fabrication of negative microstructured polydimethylsiloxane molds ultimately utilized to obtain bulk polymeric micropatterned structures by replica molding. As illustrative proof of concept, this approach is employed in the field of photovoltaics to realize the first example of superhydrophobic luminescent solar concentrators (LSCs) showing superior self-cleaning properties. Following our strategy, a new dye-doped acrylate mixture is developed and optimized to ensure complete wetting of the hollow microstructures present on the mold. By judiciously tailoring the photoinitiator concentration and by implementing a tailored double-step UV-irradiation process, complete UV-photopolymerization is achieved despite the significant thickness of the target samples. The high fidelity replication of the original SL-printed features on the daughter replicas as well as their super water-repellency are successfully demonstrated. The performance of the resulting superhydrophobic LSCs is investigated at varying device dimensions and found to be comparable with state-of-the-art systems. This study demonstrates the potential of high-resolution SL-printing in combination with replication techniques as a versatile tool to reproducibly fabricate microstructured superhydrophobic polymeric bulk devices in a straightforward fashion.

Flexible Polymer Device Based on Parylene-C with Memory and Temperature Sensing Functionalities.

Polychloro-para-xylylene (parylene-C) is a flexible and transparent polymer material which has excellent chemical stability and high biocompatibility. Here we demonstrate a polymer device based on single-component parylene-C with memory and temperature sensing functionalities. The device shows stable bipolar resistive switching behavior, remarkable storage window (>104), and low operation voltages, exhibiting great potential for flexible resistive random-access memory (RRAM) applications. The I-V curves and conductive atomic force microscopy (CAFM) results verify the metallic filamentary-type switching mechanism based on the formation and dissolution of a metal bridge related to the redox reaction of the active metal electrode. In addition, due to the metallic properties of the low-resistance state (LRS) in the polymer device, the resistance in the LRS exhibits a nearly linear relationship at the temperature regime between 25 °C and 100 °C. With a temperature coefficient of resistance (TCR) of 2.136 × 10−3/°C, the device is also promising for the flexible temperature sensor applications.

Abstract 1721: Detection of CTCs in thoracic malignant tumors with "universal" CTC-chip

Abstract Background: Circulating tumor cells (CTCs) are tumor cells shed from primary tumor and circulate in the peripheral blood. CTCs, as a surrogate of distant metastasis, can be potentially useful in diagnosis and monitoring therapeutic effects in malignant tumors. Among a variety of systems for detection of CTCs, the “Cellsearch” is the only approved system for clinical use. However, EpCAM-negative tumor cells, such as those originating from non-epithelial cells and those undergoing epithelial-mesenchymal transition (EMT) cannot be captured with the “CellSearch” that is an EpCAM-based isolation system. Therefore, we have developed a novel polymeric microfluidic device (“Universal” CTC-chip) that can capture CTCs with or without EpCAM expression (AACR 2015). In the present study, we examined CTCs-detection performance of the CTC-chip in patients with thoracic malignant tumors (lung cancer [LC] as an “EpCAM-positive” tumor and malignant pleural mesothelioma [MPM] as an “EpCAM-negative” tumor) in comparison with that of the CellSearch. Methods: Peripheral blood sampled from each patient was divided and subjected to quantitative evaluation of CTCs with the CTC-chip as well as with the “CellSearch”. The CTC-chip, coated with an anti-EpCAM antibody, was used to capture CTCs in the blood samples (n=19) from lung cancer patients. To capture CTCs in the samples (n=11) from MPM patients, the CTC-chip was coated with an antibody against podoplanin that is expressed on the mesothelioma. After immuno-staining for cytokeratin and CD45 on the chip, a captured cell containing Hoechst-positive nucleus and cytokeratin-positive/ CD45-negative cytoplasm was judged as a CTC. The CTC-count for each sample was represented as the number per 7.5mL of the blood. Results: The median CTC-count detected with the CTC-chip in LC was 50 (range, 0-270), which was significantly higher than that (the median CTC-count, 0; range, 0-47) with the CellSearch (p<0.01). In the peripheral blood sampled from MPM patients, CTC was detected in only one patient using the CellSearch, but was detected in all 11 patients with the median CTC-count of 144 (range 0-470). Conclusion: The “universal” CTC-chip achieved higher performance in detection of CTCs of thoracic malignant tumors as compared with the CellSearch. The updated data will be presented at the AACR annual meeting 2017. Citation Format: Kazue Yoneda, Taiji Kuwata, Yasuhiro Chikaishi, Kenichi Kobayashi, Sakiko Yura, Hiroki Matsumiya, Masatoshi Kanayama, Akihiro Taira, Yusuke Nabe, Shinji Shinohara, Masaru Takenaka, Soichi Oka, Ayako Hirai, Yuko Tashima, Naoko Imanishi, Koji Kuroda, Fumihiro Tanaka. Detection of CTCs in thoracic malignant tumors with "universal" CTC-chip [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1721. doi:10.1158/1538-7445.AM2017-1721

Electrochemical strain microscopy probes morphology-induced variations in ion uptake and performance in organic electrochemical transistors

Ionic transport phenomena in organic semiconductor materials underpin emerging technologies ranging from bioelectronics to energy storage. The performance of these systems is affected by an interplay of film morphology, ionic transport and electronic transport that is unique to organic semiconductors yet poorly understood. Using in situ electrochemical strain microscopy (ESM), we demonstrate that we can directly probe local variations in ion transport in polymer devices by measuring subnanometre volumetric expansion due to ion uptake following electrochemical oxidation of the semiconductor. The ESM data show that poly(3-hexylthiophene) electrochemical devices exhibit voltage-dependent heterogeneous swelling consistent with device operation and electrochromism. Our data show that polymer semiconductors can simultaneously exhibit field-effect and electrochemical operation regimes, with the operation modality and its distribution varying locally as a function of nanoscale film morphology, ion concentration and potential. Importantly, we provide a direct test of structure-function relationships by correlating strain heterogeneity with local stiffness maps. These data indicate that nanoscale variations in ion uptake are associated with local changes in polymer packing that may impede ion transport to different extents within the same macroscopic film and can inform future materials optimization.

Synthesis and Characterisation of Novel Thiophene Based Azomethine Polymers and Study of Their Liquid Crystalline, Electrochemical and Optoelectronic Properties

This work reports the synthesis, structural characterisation, liquid crystallinity, luminescence and electroluminescence of novel thiophene azomethine polymers. The polymers under study were prepared via oxidative polymerisation of four novel monomers at room temperature using iron (III) chloride. The chemical structures of the prepared monomers and polymers were confirmed by infrared and 1H and 13CNMR spectroscopy. Molecular masses were determined for monomers and polymers by gas/liquid chromatography-mass spectrometry (GC/LC-MS) and by gel-permeation (size exclusion) chromatography (SEC), respectively. Thermal stability studies of the prepared materials were achieved by thermogravimetric analysis (TGA), and the onset of weight loss To and the endset Tmax were calculated from the thermograms. Liquid crystalline mesophases and phase changes of the monomers and polymers were studied by differential scanning calorimetry (DSC) and polarised optical microscopy (POM), and the glass transition temperatures Tg of the polymers were determined from the DSC curves. The electrochemical band gaps, HOMO and LUMO energy levels were measured by cyclic voltammetry. UV-visible absorption-emission spectra (liquid and solid films) of the polymers were obtained at room temperature with different solvents. Optical band gaps were calculated from the absorption edges, and were in good agreement with those estimated from cyclic voltammetry. Mixing the polymers with lanthanide salts such as EuCl3 and YbCl3 gave modified fluorescence, and the light emitted was much more intense than that from the pure polymers. Polymer based light-emitting diodes (PLEDs) were fabricated by spin coating, and their current-voltage characteristics were measured. In preliminary work, the polymer devices were found to produce electroluminescent spectra similar to the PL spectra of the corresponding samples. Molecular modelling studies were performed both on polymer segments and monomer molecules; the absorption spectra of the prepared polymers, HOMO and LUMO energy levels were calculated with ZINDO using AMI geometry optimisation.

Biodegradable Polymer Biolimus-Eluting Stents Versus Durable Polymer Everolimus-Eluting Stents in Patients With Coronary Artery Disease: Final 5-Year Report From the COMPARE II Trial (Abluminal Biodegradable Polymer Biolimus-Eluting Stent Versus Durable Polymer Everolimus-Eluting Stent)

ObjectivesThis analysis investigates the 5-year outcomes of the biodegradable polymer biolimus-eluting stent (BP-BES) and durable polymer everolimus-eluting stent (DP-EES) in an all-comers population undergoing percutaneous coronary intervention. BackgroundRecent 1- and 3-year results from randomized trials have indicated similar safety and efficacy outcomes of BP-BES and DP-EES. Whether benefits of the biodegradable polymer device arise over longer follow-up is unknown. Moreover, in-depth, prospective, long-term follow-up data on metallic drug-eluting stents with durable or biodegradable polymers are scarce. MethodsThe COMPARE II trial (Abluminal Biodegradable Polymer Biolimus-Eluting Stent Versus Durable Polymer Everolimus-Eluting Stent) was a prospective, randomized, multicenter, all-comers trial in which 2,707 patients were randomly allocated (2:1) to BP-BES or DP-EES. The pre-specified endpoint at 5 years was major adverse cardiac events, a composite of cardiac death, nonfatal myocardial infarction, or target vessel revascularization. ResultsFive-year follow-up was available in 2,657 patients (98%). At 5 years, major adverse cardiac events occurred in 310 patients (17.3%) in the BP-BES group and 142 patients (15.6%) in the DP-EES group (p = 0.26). The rate of the combined safety endpoint all-cause death or myocardial infarction was 15.0% in the BP-BES group versus 14.8% in the DP-EES group (p = 0.90), whereas the efficacy measure target vessel revascularization was 10.6% versus 9.0% (p = 0.18), respectively. Interestingly, definite stent thrombosis rates did not differ between groups (1.5% for BP-BES vs. 0.9% for DP-EES; p = 0.17). ConclusionsThe 5-year analysis comparing biodegradable polymer-coated BES and the durable polymer-coated EES confirms the initial early- and mid-term results regarding similar safety and efficacy outcomes in this all-comers percutaneous coronary intervention population.

Mapping intermediate degradation products of poly(lactic-co-glycolic acid) in vitro.

There is widespread interest in using absorbable polymers, such as poly(lactic-co-glycolic acid) (PLGA), as components in the design and manufacture of new-generation drug eluting stents (DES). PLGA undergoes hydrolysis to progressively degrade through intermediate chemical entities to simple organic acids that are ultimately absorbed by the human body. Understanding the composition and structure of these intermediate degradation products is critical not only to elucidate polymer degradation pathways accurately, but also to assess the safety and performance of absorbable cardiovascular implants. However, analytical approaches to determining the intermediate degradation products have yet to be established and evaluated in a standard or regulatory setting. Hence, we developed a methodology using electrospray ionization mass spectrometry to qualitatively and quantitatively describe intermediate degradation products generated in vitro from two PLGA formulations commonly used in DES. Furthermore, we assessed the temporal evolution of these degradation products using time-lapse experiments. Our data demonstrated that PLGA degradation products via heterogeneous cleavage of ester bonds are modulated by multiple intrinsic and environmental factors, including polymer chemical composition, degradants solubility in water, and polymer synthesis process. We anticipate the methodologies and outcomes presented in this work will elevate the mechanistic understanding of comprehensive degradation profiles of absorbable polymeric devices, and facilitate the design and regulation of cardiovascular implants by supporting the assessments of the associated biological response to degradation products. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1129-1137, 2018.

Multistate proteinous biomemory device based on redox controllable hapten cross-linker

A multistate biomemory device consisting of cytochrome c (Cyt-c) photosensitively cross-linked by MACys-Ru(bipyr)2-MACys hapten molecules, which have memory effect through a charge transfer mechanism, has been developed. In this study, it has suggested a highly resolute surface-confined switch composed a signal-enhanced electro-active protein (Cyt-c) co-polymerized on the gold substrates that can be controlled by redox property through Ruthenium based cysteine monomer hapten, MACys-Ru(bipyr)2-MACys as an ANADOLUCA photosensitive cross-linker. The photosensitive cross-linking of the Cyt-c protein on the gold surface topography has been determined by the scanning electron microscopy (SEM). Two state memory functions, writing and erasing of the developed biomemory device, have been investigated by the chronoamperometry (CA) and open-circuit potential amperometry (OCPA). The polymeric proteinous memory device, p(MACys-Ru(bipyr)2-MACys-co-Cyt-c) layer, on the gold electrode is stable and repeatable up to with 104 times continuous cycle.