Depolymerized Chitosan-g-[Poly(MMA-co-HEMA-cl-EGDMA)] Based Nanogels for Controlled Local Release of Bupivacaine.

This study is designed to formulate and characterize chitosan-based nanogels that provide the controlled delivery of anesthetic drugs, such as bupivacaine (BPV), for effective postoperative pain management over prolonged periods of time. Drug carriers of chitosan/poly (MMA-co-HEMA-cl-EGDMA) (CsPMH) nanogels were prepared by varying the composition of comonomers such as MMA, HEMA, and redox initiator CAN. The nanogels were then characterized using FTIR, TGA, SEM, and TEM. The CsPMH nanogels showed greater encapsulation efficiencies from 43.20-91.77%. Computational studies were also conducted to evaluate the interaction between the drug and CsPMH nanoparticles. Finally, BPV-loaded nanoparticles were used to examine their in vitro release behavior. At pH 7.4, all the drug carriers displayed the "n" value around 0.7, thus the BPV release follows anomalous diffusion. Drug carrier 7 demonstrated a steady and sustained release of BPV for approximately 24 h and released about 91% of BPV, following the K-P mechanism of drug release. On the other hand, drug carrier 6 exhibited controlled release for approximately 12 h and released only 62% of BPV.

Dual (pH- and ROS-) Responsive Antibacterial MXene-Based Nanocarrier for Drug Delivery.

In this study, a novel MXene (Ti3C2Tx)-based nanocarrier was developed for drug delivery. MXene nanosheets were functionalized with 3, 3'-diselanediyldipropionic acid (DSeDPA), followed by grafting doxorubicin (DOX) as a model drug to the surface of functionalized MXene nanosheets (MXene-Se-DOX). The nanosheets were characterized using scanning electron microscopy, atomic force microscopy (AFM), transmission electron microscopy, energy-dispersive X-ray spectroscopy (EDX), nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and zeta potential techniques. The drug-loading capacity (17.95%) and encapsulation efficiency (41.66%) were determined using ultraviolet-visible spectroscopy. The lateral size and thickness of the MXene nanosheets measured using AFM were 200 nm and 1.5 nm, respectively. The drug release behavior of the MXene-Se-DOX nanosheets was evaluated under different medium conditions, and the nanosheets demonstrated outstanding dual (reactive oxygen species (ROS)- and pH-) responsive properties. Furthermore, the MXene-Se-DOX nanosheets exhibited excellent antibacterial activity against both Gram-negative E. coli and Gram-positive B. subtilis.

Folic Acid-Polyethyleneimine Functionalized Mesoporous Silica Nanoparticles as a Controlled Release Nanocarrier.

In an effort to develop a biocompatible, cancer-targetable, controllable carrier for use in smart delivery systems, including drug delivery, this study designed a novel polymer-mesoporous silica nanoparticle hybrid material functionalized with dicarboxylic acid-modified MCM-41 (DA-MCM41) and branched polyethylenimine (PEI). First, mesoporous silica nanoparticles (MSNs) were coated with a folic acid (FA)-PEI layer; MCM-41 was prepared by a sol-gel process and diacidfunctionalized MCM-41 was prepared by post-modification. Subsequently, DA-MCM-41 was coated with FA grafted PEI via an electrostatic interaction. The cellular uptake of DA-MCM-41 and the FAPEI layered MSNs by MCF-7 cells was evaluated using dansyl labeled methylene blue (MB). The FA-PEI-functionalized MSNs exhibited higher cellular uptake to MCF-7 cells than DA-MCM-41. This novel nanocarrier was internalized into the targeted tumor cells site-specifically by FA-mediated internalization and the pH-responsive release of guest molecules (here, methylene blue) was realized by an electrostatic interaction between FA-PEI and DA-MCM-41. Overall, FA-PEI-functionalized MSNs may have potential applications in the targeted and controlled delivery of guest molecules for cancer therapy.

Functionalized and Monodispersed Mesoporous Silica Nanospheres with a Schiff-Base for Metal Ion Adsorption.

Mesoporous silica nanospheres (MSNs-AH) with a Schiff-base ligand were synthesized using a snap-top strategy and post-synthetic grafting strategy for metal ion adsorption. The mesoporous MSNs-AH with the Schiff-base ligand were used for the adsorption of metal ions from artificial wastewater and artificial seawater. The adsorption characteristics of the functionalized adsorbents for various metal ions were tested for different adsorption times (1~48 h) in artificial wastewater and artificial seawater. In the case of artificial wastewater, the functionalized adsorbents had no preferential selectivity for metal ions except for Na+ ions, even though the MSNs-AH adsorbent adsorbed most of the metal ions investigated in this work, including Li+, Co2+, Ca2+, Fe3+, Mn2+, Mg2+, Al3+, Zn2+, and Ni2+. In the case of artificial seawater, however, the MSN absorbent showed high selectivity for Li+ ions.

Polymer Based Hybrid Nanocomposites; A Progress Toward Enhancing Interfacial Interaction and Tailoring Advanced Applications.

Organic/inorganic hybrid nanocomposites, in particular polymer based hybrid nanocomposites, constitute emerging advanced materials since they combine unique properties from the inorganic and organic (i. e. polymeric) components. We investigated three different hybrid nanocomposites depending on dimensions of the dispersed phase in the nanometer range,; polymer-layered silicate (PLS) nanocomposites where polymers are mixed with layered silicates, polymer/graphene oxide hybrid nanocomposites, and polymer hybrid nanocomposites with reinforcing polymers with isodimensional phases of inorganic silicas using sol-gel reactions. This Accounts reports the chronological progress of our landmark results on the polymer based hybrid nanocomposites of the three characteristic types that have been prepared in my laboratory for more than two decades, with their impacts, importance and advanced application of the related research fields for readers.

Surface Enrichment of Fluorocarbon End-Capped Polymers with Different Fluorocarbon Lengths.

This study investigated the surface structure of fluorocarbon end-capped l-poly(lactide)s (F-PLLA) with different fluorocarbon lengths by electron spectroscopy for chemical analysis (ESCA). Fluorocarbon chains of three lengths (F(CF2)n(CH2)2, where n = 6, 8, and 10) have been synthesized as the terminal group to PLLA. Angular dependent ESCA revealed that the fluorocarbon groups are segregated at the surface. Further, the results show the surface coverage of fluorocarbon groups rapidly increases with increasing the length of fluorocarbon end groups (synergy effect). The surface composition of F-PLLAs can be controlled by changing the length of fluorocarbon.

Recent advances in superhydrophobic nanomaterials and nanoscale systems.

This review describes the recent advances in the field of superhydrophobic nanomaterials and nanoscale systems. The term superhydrophobic is defined from the surface properties when the surface shows the contact angle (CA) higher than 150 degrees. This could be well known from the lotus effect due to the non-stick and self-cleaning properties of the lotus leaf (LL). We briefly introduced the methods of preparing superhydrophobic surfaces using top-down approaches, bottom-up approaches and a combination of top-down and bottom-up approaches and various ways to prepare superhydrophobic nanomaterials and nanoscale systems using the bio-inspired materials, polymer nanocomposites, metal nanoparticles graphene oxide (GO) and carbon nanotubes (CNTs). We also pointed out the recent applications of the superhydrophobic nanomaterials and nanoscale systems in oil-spill capture and separations, self-cleaning and self-healing systems, bio-medicals, anti-icing and anti-corrosive, electronics, catalysis, textile fabrics and papers etc. The review also highlights the visionary outlook for the future development and use of the superhydrophobic nanomaterials and nanoscale systems for a wide variety of applications.

Functionalized mesoporous silicas with crown ether moieties for selective adsorption of lithium ions in artificial sea water.

Lithium ion has been increasingly recognized in a wide range of industrial applications. In this work, we studied on the adsorption of Li+ in the artificial seawater with high selectivity using methyl-crown ether (AC-SBA-15) and aza-crown ether (HMC-SBA-15) moieties-functionalized mesoporous silica materials. First, methyl-crown ether and aza-crown ether moieties-functionalized mesoporous silica materials were synthesized via two-step post-synthesis process using a grafting method. The functionalized materials were employed to the metal ion adsorption from aqueous solution (artificial seawater) containing Li+, Co2+, Cr3+ and Hg2+. The prepared hybrid material showed high selectivity for Li+ ion in the artificial seawater at pH 8.0. The absorbed amount of Li+ was 73 times higher than Cr3+ for aza-crown ether containing AC-SBA-15 as an absorbent. The absorbed amount of Co2+ (4.5 x 10(-5) mol/g), Cr3+ (1.5 x 10(-5) mol/g) and Hg2+ (2.25 x 10(-4) mol/g) were remarkably lower than the case of Li+. On the other hand, the absorbed amount of various metal ions of HMC-SBA-15 with amine groups in alky chains and crown ether moieties were 1.1 x 10(-3) mol/g for Li+, 5.0 x 10(-5) mol/g for Co2+, 2.9 x 10(-4) mol/g for Cr3+, 2.8 x 10(-4) mol/g for Hg2+ mol/g, respectively.

Cyclic ligand functionalized mesoporous silica (SBA-15) for selective adsorption of Co2+ ion from artificial seawater.

Hard donor atoms (N and O) containing macrocyclic ligand was synthesized and further functionalized with mesoporous SBA-15 materials by chemical modification method. The modification was achieved by the immobilization of 3-chloropropyltriethoxysilane (CIPTES) onto mesoporous silica surface followed by post grafting route. The resulting material (Py-Cy-SBA-15) has been characterized by low angle X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm, Fourier-transform infrared (FT-IR) spectroscopy, 29Si and 13C CP MAS NMR spectroscopic analyses, Thermogravimetric analysis (TGA) and elemental analysis. The long range orders of the materials were identified by transmission electron microscopy (TEM). The functionalized material was employed to the heavy metal ions adsorption from aqueous solution containing Cu2+, Co2+, Zn2+, Cd2+ and Cr2+. The prepared hybrid material showed high selectivity and adsorption capacity for Co2+ ion at pH 8.0.

Chitosan and chitosan-co-poly(epsilon-caprolactone) grafted multiwalled carbon nanotube transducers for vapor sensing.

Vapor sensitive transducer films consisting of chitosan grafted (CNT-CS) and chitosan-co-polycaprolactone grafted (CNT-CS-PCL) multiwalled carbon nanotubes were prepared using a spray layer-by-layer technique. The synthesized materials (CNT-CS and CNT-CS-PCL) were characterized by Fourier transform infrared spectroscopy, 13C CP/MAS solid state nuclear magnetic resonance spectroscopy and thermogravimetric analysis. Both CNT-CS and CNT-CS-PCL transducers were analyzed for the response of volatile organic compounds and toluene vapors. The ranking of the relative resistance (A(r)) for both chitosan based transducers were as follows: toluene < chloroform < ethanol < methanol. The CNT transducer (CNT-CS) was correlated selectively with an exponential law to the inverse of Flory-Huggins interaction parameters, chi12. Dosing the films on the interdigitated electrodes with methanol, ethanol, chloroform and toluene vapors increased the film resistance of CNT-CS but decreased the resistance of CNT-CS-PCL compared to that of the reported transducers.

Derivatization of Hyaluronan to Target Neuroblastoma and Neuroglioma Expressing CD44.

Therapeutics for actively targeting over-expressed receptors are of great interest because the majority of diseased tissues originate from normal cells and do not possess a unique receptor from which they can be differentiated. One such receptor is CD44, which has been shown to be highly overexpressed in many breast cancers and other types of cancer cells. While CD44 has been documented to express low levels in normal adult neurons, astrocytes, and microglia, this receptor may be overexpressed by neuroblastoma and neuroglioma. If differential expression exists between normal and cancerous cells, hyaluronan (HA) could be a useful carrier that targets carcinomas. Thus, HA was conjugated with resveratrol (HA-R), and its efficacy was tested on cortical-neuroblastoma hybrid, neuroblastoma, and neuroglioma cells. Confocal and flow cytometry showed these cells express CD44 and are able to bind and uptake HA-R. The toxicity of HA-R correlated well with CD44 expression in this study. Therefore, conjugating resveratrol and other chemotherapeutics to HA could minimize the side effects for normal cells within the brain and nervous system and could be a viable strategy for developing targeted therapies.

Rare-earth metal oxide doped transparent mesoporous silica plates under non-aqueous condition as a potential UV sensor.

Transparent mesoporous silica plates doped with rare-earth metal oxide were prepared using solvent-evaporation method based on the self-organization between structure-directing agent and silicate in a non-aqueous solvent. A triblock copolymer, Pluronic (F127 or P123), was used as the structure-directing agent, while tetraethyl orthosilicate (TEOS) was used as a silica source. The pore diameter and the surface area of the mesoporous silica plate prepared with the optimized conditions were ca 40 A and 600 m2 g(-1), respectively, for both structure-directing agent. Rare-earth metal oxides (Eu, Tb, Tm oxide) in mesochannel were formed via one-step synthetic route based on the preparation method of a silica plate. Optical properties of rare-earth metal oxide-doped mesoporous silica plates were investigated by UV irradiation and photoluminescence (PL) spectroscopy. Under the exitation wavelength of 254 nm, the doped mesoporous silica plates emitted red, green and blue for Eu, Tb and Tm oxides, respectively. Rare-earth metal oxide-doped mesoporous silica plates showed enhanced PL intensity compared to that of the bulk rare-earth metal oxide.

Structural Designs of Transparent Polyimide Films with Low Dielectric Properties and Low Water Absorption: A Review.

The rapid development of communication networks (5G and 6G) that rely on high-speed devices requiring fast and high-quality intra- and inter-terminal signal transmission media has led to a steady increase in the need for high-performance, low-dielectric-constant (Dk) (<2.5) materials. Consequently, low-dielectric polymeric materials, particularly polyimides (PIs), are very attractive materials that are capable of meeting the requirements of high-performance terminal devices that transmit broadband high-frequency signals. However, such a PI needs to be properly designed with appropriate properties, including a low Dk, low dielectric loss (Df), and low water absorptivity. PI materials are broadly used in various fields owing to their superior property/processibility combinations. This review summarizes the structural designs of PIs with low Dk and Df values, low water-absorbing capacity, and high optical transparency intended for communication applications. Furthermore, we characterize structure-property relationships for various PI types and finally propose structural modifications required to obtain useful values of the abovementioned parameters.

pH Sensitive Drug Delivery Behavior of Palmyra Palm Kernel Hydrogel of Chemotherapeutic Agent.

This study examined the gel behavior of naturally-occurring palmyra palm kernel (PPK). Due to the presence of polysaccharide in PPK hydrogels, they exhibit excellent swelling behavior in response to pH. Chemotherapeutic drug 5-fluorouracil (5-FU) was encapsulated in these gels using an equilibrium swelling technique. It was found that 5-FU had an encapsulation efficiency of up to 62%. To demonstrate the drug stability in the gels, the PPK hydrogels were characterized using fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction. The results showed that the PPK hydrogel matrix contained molecularly dispersed 5-FU drug. The PPK hydrogel exhibited a denser structure and a rough surface, according to images obtained by scanning electron microscopy. In vitro release tests were carried out at pH 1.2 (gastric fluid) and 7.4 (intestinal fluid). The efficacy of the encapsulation and the release patterns were influenced by the network topology of the PPK hydrogel. The release patterns showed that 5-FU was released gradually over a time internal of more than 12 h. The findings suggest that naturally-occurring PPK hydrogels loaded with chemotherapeutic drugs could be employed to treat colon cancer.

Electrocatalytic Oxygen Reduction Reaction of Graphene Oxide and Metal-Free Graphene in an Alkaline Medium.

Graphene is a well-known two-dimensional material with a large surface area and is used for numerous applications in a variety of fields. Metal-free carbon materials such as graphene-based materials are widely used as an electrocatalyst for oxygen reduction reactions (ORRs). Recently, more attention has been paid to developing metal-free graphenes doped with heteroatoms such as N, S, and P as efficient electrocatalysts for ORR. In contrast, we found our prepared graphene from graphene oxide (GO) by the pyrolysis method under a nitrogen atmosphere at 900 °C has shown better ORR activity in aqueous 0.1 M potassium hydroxide solution electrolyte as compared with the electrocatalytic activity of pristine GO. At first, we prepared various graphene by pyrolysis of 50 mg and 100 mg of GO in one to three alumina boats and pyrolyzed the samples under a N2 atmosphere at 900 °C. The prepared samples are named G50-1B to 3B and G100-1B and G100-2B. The prepared GO and graphenes were also analyzed under various characterization techniques to confirm their morphology and structural integrity. The obtained results suggest that the ORR electrocatalytic activity of graphene may differ based on the pyrolysis conditions. We found that G100-1B (Eonset, E1/2, JL, and n values of 0.843, 0.774, 4.558, and 3.76) and G100-2B (Eonset, E1/2, and JL values of 0.837, 0.737, 4.544, and 3.41) displayed better electrocatalytic ORR activity, as did Pt/C electrode (Eonset, E1/2, and JL values of 0.965, 0.864, 5.222, and 3.71, respectively). These results display the wide use of the prepared graphene for ORR and also can be used for fuel cell and metal-air battery applications.

A molecular keypad lock that uses Cu(II) cations and H2PO4- anions as inputs.

Molecular keypad lock devices have considerable advantages over simple molecular logic gates because the output signals not only depend on the proper combination of inputs but also on the sequence of the input signals. Especially, keeping in view the role played by transition metal ions, anions and electronic devices in day to day life, the development of applications in electronic devices upon chemical inputs of these cations or anions in a sequential manner is very important. Previously, we designed a 2, 2'-dihydroxyazobenzene (DHAB)-based model of a keypad lock system depending on the inputs sequence of Zn(ll) cations and H2PO4- anions. In the present work, we studied the properties of 2-((E)-(2-((E)-3-bromoallyloxy)phenyl)diazenyl)phenol, compound 1, toward anions in the absence and presence of Cu(ll) cations, in order to further explore the potential applications of DHAB-based sensing systems. We demonstrated that the application of compound 1 with the inputs of Cu(ll) cations and H2PO4- anions could be realized as a molecular keypad lock which could be of future interest in molecular computing.

Synthesis and characterization of multifunctional periodic mesoporous organosilica from diureidophenylene bridged organosilica precursor.

This paper reports the periodic mesoporous organosilicas (PMOs) functionalised with newly synthesized bis-silylated (1,1(1,4-phenylene (bis-3-(3-triethoxysilylpropyl)urea)(BSBDA)) organosilica with 1,2-bis(triethoxysilyl) ethane (BTSE) using a co-condensation process. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption-desorption, NMR (proton, 13C and 29Si) spectra, and MALDI-TOF were used to characterise and evaluate the structural properties. The results showed that BSBDA is linked covalently to the mesochannel of the PMO frameworks. The pore size and overall structural properties in the functionalised PMOs were found to depend on the loading amounts of BSBDA. The overall results suggested that the highly functionalised PMOs could be tuned even at high BSBDA loadings (25 wt%).

Thermally stable carbazole-diimides as hole transport materials for organic light-emitting devices.

We synthesized new carbazole-diimide hole-transporting materials with different dianhydride groups by thermal imidization. The imide moieties were introduced to improve thermal stability of a carbazole hole transport molecule. Result showed that the carbazole-diimdes exhibit good thermal stability with glass transition temperature of 142-182 degrees C and degradation temperature of approximately 450 degrees C as well as good optical transparency in the visible region. The organic light-emitting device (OLED) using alicyclic diimide (CBCZ) shows maximum luminance approximately 8,600 cd/m2 at 12 V and current efficiency of 2.1 cd/A. With optimization of fabricating conditions, the thermally stable CBCZ is expected to be used as a promising hole-transporting material with higher efficiency and durability.

Transparent anti-stain coatings with good thermal and mechanical properties based on polyimide-silica nanohybrids.

In this work, we synthesized polyimide/silica hybrid materials via sol-gel method using a fluorinated poly(amic acid) silane precursor and a variety of perfluorosilane contents. We studied the influence of a hybrid coating film with the following characteristics; hydrophobicity, oleophobicity, optical transparency, and surface hardness of the coating films. The hybrid coatings with the fluorosilane contents up to 10 wt% are optically transparent and present good thermal stability with a degradation temperature of > 500 degrees C as well as a glass transition of > 300 degrees C. Both water contact angle and oil contact angle increase rapidly with introducing small amount of the fluorosilane in the hybrids and reaches the maximum of 115 degrees and 61 degrees, respectively. The hardness of the hybrid coatings increases up to 5H with an increase of the FTES content in the hybrids. These colorless, transparent, and thermally stable hybrid materials could be suitable for applications as anti-stain coatings.

Synthesis and characterization of new donor-acceptor type copolymers based on fluorene derivatives for photovoltaic solar cells.

In this paper, we demonstrated the successful synthesis of newly designed copolymers, C1 and C2, with donor-acceptor type structure. Both C1 and C2 copolymers contained 9,9-dioctylfluorene-2,7-bis(trimethyleneboronate) as one constructional unit to improve the solubility in common organic solvents. The other constructional unit was 2,3-bis(5-bromothiophen-2-yl)acrylonitrile (DTDBAL) for C1, while 4,7-dibromobenzo[c][1,2,5]thiadiazole unit, 5,5'-dibromo-2,2'-bithiophene unit and N1, N1-bis(4-bromophenyl)-N4,N4-bis(4-(2-phenylpropan-2-yl)phenyl)benzene-1,4-diamine are for C2. We fabricated photovoltaic devices based on the C1 and the C2 copolymers with Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer, PC70BM layer, TiOx layer, and aluminum (Al) electrode. The bulk heterojuntion photovoltaic devices using these copolymers as electron donor and PC70BM as the acceptor exhibited good device performances when measured at 100 mW cm-2. The power conversion efficiency (PCE) of the C1 device reached 0.45% with Voc, Jsc and FF of 0.51, 2.50 and 35%, respectively. The PCE of the C2 device reached 0.34% with Voc, Jsc, and FF of 0.56, 2.01 and 30%, respectively.