Investigating the Mobility-Compressibility Properties of Conjugated Polymers by the Contact Film Transfer Method with Prestrain.

Up to now, researches on the mobility-stretchability of semiconducting polymers are extensively investigated, but little attention was  paid to their morphology and field-effect transistor characteristics under compressive strains, which is equally crucial in wearable electronic applications. In this work, a contact film transfer method is applied to evaluate the mobility-compressibility properties of conjugated polymers. A series of isoindigo-bithiophene conjugated polymers with symmetric carbosilane side chains (P(SiSi)), siloxane-terminated alkyl side chains (P(SiOSiO)), and combined asymmetric side chains (P(SiOSi)) are investigated. Accordingly, a compressed elastomer slab is used to transfer and compress the polymer films by releasing prestrain, and the morphology and mobility evolutions of these polymers are tracked. It is found that P(SiOSi) outperforms the other symmetric polymers including P(Si─Si) and P(SiO─SiO), having the ability to dissipate strain with its shortened lamellar spacing and orthogonal chain alignment. Notably, the mechanical durability of P(SiOSi) is also enhanced after consecutive compress-release cycles. In addition, the contact film transfer technique is demonstrated to be applicable to investigate the compressibility of different semiconducting polymers. These results demonstrate a comprehensive approach to understand the mobility-compressibility properties of semiconducting polymers under tensile and compressive strains.

Platysma-sparing vascularized submental lymph node flap transfer for extremity lymphedema.

BACKGROUND AND OBJECTIVES: Due to its consistent vascular and lymphatic anatomy, the vascularized submental lymph node flap is a reliable option for lymphedema treatment. Despite these advantages, flap harvest requires resection of platysma, which may cause a marginal mandibular nerve pseudo-paralysis. The aim of this study was to investigate the donor site morbidity of an innovative platysma-sparing vascularized submental lymph node flap transfer for treating extremity lymphedema. METHODS: Ten patients undergoing platysma sparing submental lymph-node flap harvest were prospectively enrolled in the study and compared with a control group of 10 patients who underwent standard submental lymph-node flap harvest. Photogrammetry analysis was used to assess donor site morbidity with regards to marginal mandibular nerve pseudo-paralysis. RESULTS: All flaps survived. No necrosis of the skin paddle was observed in both groups. There were no marginal mandibular nerve palsies in both group. There were no cases of marginal mandibular nerve pseudo-paralysis in the platysma sparing group. CONCLUSIONS: The platysma sparing submental flap, while offering comparable functional improvement for extremity lymphedema, has the advantages of maximizing nerve and muscular preservation, significantly reducing donor site morbidity. J. Surg. Oncol. 2017;115:48-53. © 2017 Wiley Periodicals, Inc.

Radical and Atom Transfer Halogenation (RATH): A Facile Route for Chemical and Polymer Functionalization.

This work demonstrates a new halogenation reaction through sequential radical and halogen transfer reactions, named as "radical and atom transfer halogenation" (RATH). Both benzoxazine compounds and poly(2,6-dimethyl-1,4-phenylene oxide) have been demonstrated as active species for RATH. Consequently, the halogenated compound becomes an active initiator of atom transfer radical polymerization. Combination of RATH and sequential ATRP provides an convenient and effective approach to prepare reactive and crosslinkable polymers. The RATH reaction opens a new window both to chemical synthesis and molecular design and preparation of polymeric materials.

3D-Printed proangiogenic patches of photo-crosslinked gelatin and polyurethane hydrogels laden with vascular cells for treating vascular ischemic diseases.

Engineering vascularized tissues remains a promising approach for treating ischemic cardiovascular diseases. The availability of 3D-bioprinted vascular grafts that induce therapeutic angiogenesis can help avoid necrosis and excision of ischemic tissues. Here, using a combination of living cells and biodegradable hydrogels, we fabricated 3D-printed biocompatible proangiogenic patches from endothelial cell-laden photo-crosslinked gelatin (EC-PCG) bioink and smooth muscle cell-encapsulated polyurethane (SMC-PU) bioink. Implantation of 3D-bioprinted proangiogenic patches in a mouse model showed that EC-PCG served as an angiogenic capillary bed, whereas patterned SMC-PU increased the density of microvessels. Moreover, the assembled patterns between EC-PCG and SMC-PU induced the geometrically guided generation of microvessels with blood perfusion. In a rodent model of hindlimb ischemia, the vascular patches rescued blood flow to distal tissues, prevented toe/foot necrosis, promoted muscle remodeling, and increased the capillary density, thereby improving the heat-escape behavior of ischemic animals. Thus, our 3D-printed vascular cell-laden bioinks constitute efficient and scalable biomaterials that facilitate the engineering of vascular patches capable of directing therapeutic angiogenesis for treating ischemic vascular diseases.

Accurate Prediction of Submental Lymph Nodes Using Magnetic Resonance Imaging for Lymphedema Surgery.

BACKGROUND: Submental lymph node transfer has proved to be an effective approach for the treatment of lymphedema. This study was to investigate the anatomy and distribution of vascularized submental lymph node (VSLN) flap using magnetic resonance imaging (MRI) and their clinical outcome. METHODS: Fifteen patients who underwent 19 VSLN flap transfers for upper or lower limb lymphedema were retrospectively analyzed. The number of submental lymph nodes was compared among preoperative MRI, preoperative sonography, intraoperative finding, postoperative sonography, and postoperative computed tomography angiography. The outcome was compared between preoperatively and postoperatively. RESULTS: All 19 VSLN flaps survived. Two hundred fifteen lymph nodes were identified in 30 submandibular regions by MRI. The mean number of submental lymph nodes on preoperative MRI was 7.2 ± 2.4, on preoperative sonography was 3.2 ± 1.1, on intraoperative finding was 3.1 ± 0.6, postoperative sonography was 4.6 ± 1.8, and postoperative CTA was 5.2 ± 1.9. Sixty-one percent of the lymph nodes were located in the central two-quarters of the line drawn from the mental protuberance to the mandibular angle. The actual harvest rate of submental lymph nodes was 72.2%. At a 12-month follow-up, mean episodes of cellulitis were improved from 2.7 ± 0.6 to 0.8 ± 0.2 (P < 0.01); mean of circumferential difference was improved 3.2 ± 0.4 cm (P < 0.03). The overall lymphedema quality-of-life was improved 4.9 ± 0.3 (P < 0.04). CONCLUSIONS: The preoperative MRI is a useful tool for the detection of mean 7.2 submental lymph nodes. Mean 72.2% of submental lymph nodes can be successfully transferred for extremity lymphedema with optimal functional recovery.

Preparation, characterizations and anti-pollutant activity of 7,3',4'-trihydroxyisoflavone nanoparticles in particulate matter-induced HaCaT keratinocytes.

BACKGROUND: 7,3',4'-Trihydroxyisoflavone (734THI), a secondary metabolite derived from daidzein in soybean, possesses several biological activities, including antioxidant, skin whitening and anti-atopic dermatitis properties, but the poor aqueous solubility of 734THI has limited its application in medicine and cosmetic industry. METHODS: The aim of the present study was to improve the physicochemical properties of 734THI using planetary ball mill preparation under a solvent-free process to improve its solubility and anti-pollutant activity. RESULTS: 734THI nanoparticle powder (734THIN) was successfully prepared by the planetary ball mill technique using polyvinylpyrrolidone K30 as the excipient. 734THIN effectively increased the aqueous solubility and cellular uptake of 734THI by improving its physicochemical properties, including particle size reduction, crystalline-amorphous transformation and intermolecular hydrogen bonding with polyvinylpyrrolidone K30. In addition, 734THIN inhibited the overexpression of COX-2 and MMP-9 by downregulating MAPK pathway signaling in particulate matter-exposed HaCaT keratinocytes, while raw 734THI in PBS with low aqueous solubility did not show any anti-inflammatory or antiaging activity. CONCLUSION: 734THIN may be used as an additive in anti-pollutant skin care products for preventing particulate matter-induced inflammation and aging in skin.

Novel 3D Neuron Regeneration Scaffolds Based on Synthetic Polypeptide Containing Neuron Cue.

Neural tissue engineering has become a potential technology to restore the functionality of damaged neural tissue with the hope to cure the patients with neural disorder and to improve their quality of life. This paper reports the design and synthesis of polypeptides containing neuron stimulate, glutamic acid, for the fabrication of biomimetic 3D scaffold in neural tissue engineering application. The polypeptides are synthesized by efficient chemical reactions. Monomer γ-benzyl glutamate-N-carboxyanhydride undergoes ring-opening polymerization to form poly(γ-benzyl-l-glutamate), then hydrolyzes into poly(γ-benzyl-l-glutamate)-r-poly(glutamic acid) random copolymer. The glutamic acid amount is controlled by hydrolysis time. The obtained polymer molecular weight is in the range of 200 kDa for good quality of fibers. The fibrous 3D scaffolds of polypeptides are fabricated using electrospinning techniques. The scaffolds are biodegradable and biocompatible. The biocompatibility and length of neurite growth are improved with increasing amount of glutamic acid in scaffold. The 3D scaffold fabricated from aligned fibers can guide anisotropic growth of neurite along the fiber and into 3D domain. Furthermore, the length of neurite outgrowth is longer for scaffold made from aligned fibers as compared with that of isotropic fibers. This new polypeptide has potential for the application in the tissue engineering for neural regeneration.

Interactions of Pluronics with phospholipid monolayers at the air-water interface.

Pluronics are triblock copolymers which are extensively applied excipients shown to interact with cell membranes. The aim of our study was to apply monolayer techniques and epifluorescence microscopy to investigate the interaction behavior between selected Pluronics and phospholipid monolayers which serve as a model of cell membranes. The results showed that Pluronic L61 with hydrophobic proportions much larger than those of F68 demonstrated condensed film-like surface behavior while F68 exhibited more expanded behavior. The increments of surface pressure and the changes of image were more obvious in adding Pluronic L61 than F68 to the subphase of dipalmitoylphosphatidylcholine (DPPC) monolayers, which indicated that the interaction may be related to van der Waals forces and hydrophobic interaction. Pluronics selected with higher hydrophobicities demonstrated larger surface activities and penetration abilities while being added to the subphase of DPPC and dimyristoylphosphatidylcholine (DMPC) monolayers. Pluronic P85 and F68 were found to be squeezed to subphase at higher surface pressures, which may be attributed to their relatively higher hydrophilicities.

Preparation of a novel molecularly imprinted polymer by the sol-gel process for sensing creatinine.

A novel molecularly imprinted polymer (MIP) was prepared and used as an artificial receptor for creatinine (Cre). A sol-gel process was used to prepare the MIP. Tetraethoxysilane (TEOS) was employed as the crosslinker for the formation of a silica matrix for the MIP. Aluminum ion (Al(3+)) was chosen as the dopant to generate Lewis acid sites in the silica matrix for interactions with Cre. Through the sol-gel process, a polymeric matrix with memory sites for Cre was obtained, and this is mentioned here as the molecularly imprinted polymer for creatinine (MIP(Cre)). The imprinting efficiency of MIP(Cre) was evaluated by contrasting the adsorbed amount of Cre by MIP(Cre) with that by the corresponding non-imprinted polymer (NIP). Creatine (Cn), N-hydroxysuccinimide (NHS), and L-tyrosine (L-tyr) were selected as interferences to study the selectivity of the MIP(Cre). The interference studies were also conducted using binary mixtures, such as Cre/Cn, Cre/NHS, and Cre/L-tyr. All these studies reveal that the MIP(Cre) possess a remarkable affinity for Cre. The crucial role of Al(3+) in this system is discussed in detail. Furthermore, the effects of concentrations of Al(3+) and TEOS on the adsorbed amount of Cre by MIP(Cre) were also investigated.

Anatomical basis and clinical application of the ulnar forearm free flap for head and neck reconstruction.

OBJECTIVES/HYPOTHESIS: This study was designed to investigate the anatomical features and applications of the ulnar forearm flap in head and neck reconstructive surgery. STUDY DESIGN: A prospective study was designed to include 50 ulnar forearm free flap transplants in 50 patients. Patient defects requiring reconstructive surgery involved the buccal mucosa, tongue, floor of the mouth, upper or lower gums, lips, soft palate, and scalp. Twenty ulnar forearm flaps were analyzed along the entire ulnar artery to determine the anatomy and distribution of the ulnar artery septocutaneous perforators. RESULTS: All 50 flaps were successfully transplanted into their respective sites. The mean diameters of the ulnar artery and vein were 2.3 ± 0.6 mm and 1.7 ± 0.6 mm, respectively. Arterial and venous size mismatch was experienced in 12 and 33 flaps, respectively. The mean number of sizable perforators was 4.3 ± 1.2, and most of the first perforators were located within 5 cm of the proximal wrist crease. None of the patients experienced long-term complications concerning the ulnar nerve. CONCLUSIONS: The ulnar forearm flap is a reliably consistent source of free flap transfer because it harbors constant septocutaneous perforators and produces minimal donor site morbidities for head and neck reconstructive surgery.

Modification of glassy carbon electrode with a polymer/mediator composite and its application for the electrochemical detection of iodate.

A modified glassy carbon electrode was prepared by depositing a composite of polymer and mediator on a glassy carbon electrode (GCE). The mediator, flavin adenine dinucleotide (FAD) and the polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) were electrochemically deposited as a composite on the GCE by applying cyclic voltammetry (CV). This modified electrode is hereafter designated as GCE/PEDOT/FAD. FAD was found to significantly enhance the growth of PEDOT. Electrochemical quartz crystal microbalance (EQCM) analysis was performed to study the mass changes in the electrode during the electrodeposition of PEDOT, with and without the addition of FAD. The optimal cycle number for preparing the modified electrode was determined to be 9, and the corresponding surface coverage of FAD (Γ(FAD)) was ca. 5.11×10(-10)mol cm(-2). The amperometric detection of iodate was performed in a 100 mM buffer solution (pH 1.5). The GCE/PEDOT/FAD showed a sensitivity of 0.78 µA µM(-1) cm(-2), a linear range of 4-140 µM, and a limit of detection of 0.16 µM for iodate. The interference effects of 250-fold Na(+), Mg(2+), Ca(2+), Zn(2+), Fe(2+), Cl(-), NO(3)(-), I(-), SO(4)(2-) and SO(3)(2-), with reference to the concentration of iodate were negligible. The long-term stability of GCE/PEDOT/FAD was also investigated. The GCE/PEDOT/FAD electrode retained 82% of its initial amperometric response to iodate after 7 days. The GCE/PEDOT/FAD was also applied to determine iodate in a commercial salt.

A novel poly(3,4-ethylenedioxythiophene)/iron phthalocyanine/multi-wall carbon nanotubes nanocomposite with high electrocatalytic activity for nitrite oxidation.

In the present work, the oxidative electrochemistry of nitrite on the poly(3,4-ethylenedioxythiophene)/iron phthalocyanine/multi-wall carbon nanotubes-(PEDOT/FePc/MWCNT) modified screen-printed carbon electrodes (SPCE) has been investigated. The parameters, such as overpotential, current density and rate constant at PEDOT/FePc/MWCNT-modified SPCE, were compared with an un-modified, FePc-, and FePc/MWCNT-modified SPCE for electro-oxidation of nitrite. As compared with the un-modified SPCE, an increase in the anodic peak current density (J(pa)) (∼100%) along with a decrease in the anodic peak potential (E(pa)) of ∼150mV for electro-oxidation of nitrite at the FePc-modified SPCE was observed. When an under-layer of MWCNT was introduced onto FePc-modified SPCE, denoted as FePc/MWCNT-modified SPCE, and the number of FePc/MWCNT bilayer was optimized, the heterogeneous electron transfer rate constant (k) at FePc/MWCNT-modified SPCE was enhanced about 7.8 times as compared with that at FePc-modified SPCE. Moreover, as a layer of PEDOT film was electrodeposited onto the FePc/MWCNT-modified SPCE, denoted as PEDOT/FePc/MWCNT-modified SPCE, a significant increase in current response along with a remarkable decrease in E(pa) were noticed. This can be attributed to the pre-concentration effect induced by the electrostatic interaction between the negatively charged nitrite and oxidized PEDOT film. On the whole, the PEDOT/FePc/MWCNT-modified SPCE greatly reduces the overpotential of ∼330mV along with 3.5 times enhanced the peak current density for the electro-oxidation of nitrite as compared with un-modified SPCE. The sensitivity and limit of detection (S/N=3) for the PEDOT/FePc/MWCNT-modified SPCE were found to be as 638mAcm(-2)M(-1) and 71nM, respectively. Notably, PEDOT/FePc/MWCNT-modified SPCE has a lower sensing potential than compared to several other modified electrodes. The developed sensor was also applied for the determination of nitrite in tap water sample.

A strategic approach for tongue reconstruction to achieve predictable and improved functional and aesthetic outcomes.

BACKGROUND: Successful tongue reconstruction should restore swallowing, speech function, and cosmesis. The purpose of this prospective study was to evaluate the functional and aesthetic outcomes of tongue reconstruction using variable free flaps based on different tongue defects. METHODS: One hundred four patients with a mean age of 49±11 years underwent free tissue transfer following resection of T2 to T4 tongue cancers. The defects were classified prospectively into three groups: group A, hemiglossectomy defects (n=42) reconstructed with 33 radial forearm flaps and nine anterolateral thigh perforator flaps; group B, subtotal glossectomy defects (n=50) reconstructed with anterolateral thigh perforator (n=44) or anterolateral thigh myocutaneous flaps (n=6); and group C, total glossectomy defects (n=12) reconstructed with 12 pentagonal anterolateral thigh myocutaneous flaps. RESULTS: Two flaps failed, giving a success rate of 98.1 percent. Two patients developed partial flap loss. At a mean follow-up of 46.2 months, 33 patients were available for evaluation. Normal speech was found in 13 patients, intelligible speech was found in nine, and slurred speech was found in 11. Sixteen patients could eat a normal diet, eight could eat a soft diet, seven could eat a liquid diet, and two required tube feeding (p=0.28). The cosmetic results were rated as excellent in 19, good in nine, and fair in five patients (p=0.76). CONCLUSIONS: A strategic approach of variable flap selections based on different tongue defects may achieve predictably better functional and aesthetic outcomes. The innovative pentagonal anterolateral thigh myocutaneous flap for total tongue reconstruction creates a free neotongue tip with adequate volume, producing acceptable swallowing function and cosmesis.

Does ischemia time affect the outcome of free fibula flaps for head and neck reconstruction? A review of 116 cases.

BACKGROUND: The fibula osteoseptocutaneous flap is an excellent option for the reconstruction of segmental mandibular defects. This study was conducted to investigate the relationship between ischemia time and outcome of the fibula flap, thus establishing the critical ischemia time for this procedure. METHODS: Between February of 2003 and March of 2005, 114 patients who underwent 116 fibular osteoseptocutaneous flaps for head and neck reconstruction were reviewed retrospectively. Complications were classified as acute, subacute, or chronic based on the time at which they were detected postoperatively. Outcomes among different ischemia time groups were evaluated: group A, less than 3 hours; group B, 3 to 4 hours; group C, 4 to 5 hours; and group D, 5 to 7 hours. RESULTS: The mean success rate of the fibula osteoseptocutaneous flap was 98.3 percent. Mean flap ischemia time was 3.6±0.97 hours. Sixty-six patients (56.9 percent) experienced one or more complications at different stages (86 complications total). There were no statistically significant differences in acute, subacute, and chronic complications among the four groups (p=0.6, p=0.6, and p=0.2, chi-square test). The overall complication rate was significantly higher in group D (81.8 percent) (p=0.03, chi-square test). The partial flap loss rate was also statistically higher in group D (45.5 percent) compared with the other three groups (12.1, 12.2, and 8.7 percent) (p=0.02, chi-square test). CONCLUSIONS: : Using the fibula osteoseptocutaneous flap for head and neck reconstruction, ischemia times less than 5 hours do not increase complication rates in different postoperative stages. However, the critical ischemia time of the fibula osteoseptocutaneous flap should be limited to 5 hours to reduce partial skin paddle loss and overall complications.

Electrical properties of single and multiple poly(3,4-ethylenedioxythiophene) nanowires for sensing nitric oxide gas.

The electrical properties of conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), nanowires were studied to develop nitric oxide (NO) gas sensors with low working temperatures. A nanowire with a diameter of 300 nm was fabricated using dip-pen nanolithography (DPN) across a 55 microm gap between a pair of electrodes. The electrical properties of single or multiple PEDOT nanowires were examined by plotting the current-voltage (I-V) curves in the range -3 V to +3 V at temperatures between 298 K and 393 K. The conductance of parallel wires was normalized with respect to the dimensions of the fabricated nanowires. The single nanowire exhibited nonlinear conductance associated with hysteresis but multiple wires did not. The currents increased with the temperature and the I-V characteristics were consistent with the power law G(T)alphaT(alpha) with alpha approximately 5.14 and 5.43. The responses to NO were highly linear and reproducible, indicating that sensing using PEDOT nanowires was reliable with a minimal concentration of NO of 10 ppm.

Nano fabrication of conducting polymers for NO gas by Dip pen nanolithography.

We present a novel fabrication method by using dip pen nanolithography with Poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) for nitric oxide (NO) gas sensor in this report. PEDOT is a kind of conducting polymer which will change its conductance upon NO adsorption. Herein, we have used PEDOT with traditional thick film and DPN nanowires across electrodes. By using traditional thick film device, the lowest detection limit for NO is 3.87 ppm. The preliminary results of DPN nanowires can have aspect ratio (L/W) for up to 220 times and thus have large sensing surface area for higher sensitivity.