Bio-inspired hybrid scaffold of zinc oxide-functionalized multi-wall carbon nanotubes reinforced polyurethane nanofibers for bone tissue engineering

Shrestha, Bishnu Kumar,Shrestha, Sita,Tiwari, Arjun Prasad,Kim, Jeong-In,Ko, Sung Won,Kim, Han-Joo,Park, Chan Hee,Kim, Cheol Sang Elsevier 2017 Materials & Design Vol.133 No.-

<P><B>Abstract</B></P> <P>In this study, we prepared nanotopographical polyurethane (PU)-based bioactive scaffolds that incorporated uniformly dispersed functionalized multi-wall carbon nanotubes (<I>f</I>MWCNTs) and zinc oxide (ZnO) nanoparticles (NPs) using an electrospinning technique. We found that well dispersed <I>f</I>MWCNTs along with ZnO NPs reinforced PU fibers demonstrated significant improvement in mechanical strength, hydrophilicity, thermal stability, electrical conductivity, degradability, biomineralization, and biocompatibility. Inspired by the exciting nature of biopolymeric composite (PU/ZnO-<I>f</I>MWCNTs) membranes, these hybrid scaffolds offer extensive interest to tissue engineering as a potential biomedical application. The specific bioactive properties and cell-biomaterial interaction of electrospun scaffold containing 0.2wt% ZnO with 0.4wt% <I>f</I>MWCNTs were found to demonstrate anti-bacterial activity and cytocompatibility. Furthermore, the highly charged density, large surface-to-volume ratio, and more functional groups in <I>f</I>MWCNTs integrated on the scaffolds promote osteogenic differentiation of pre-osteoblast (MC3T3-E1) cells. Therefore, the novel as-prepared multifunctional electrospun fibrous scaffold could suggest new avenues for exploration as promising osteoproductive and osteoinductive biomaterials that offer great benefit to bone tissue engineering.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Functionalized multi-wall carbon nanotubes (<I>f</I>MWCNTs) within nanofiber enhance the electrical conductivity of scaffolds. </LI> <LI> The <I>f</I>MWCNTs (0.4 wt%) in scaffolds show good antibacterial activity. </LI> <LI> Interaction of zinc oxide and <I>f</I>MWCNTs with simulated body fluid resulting nucleation of calcium phosphate. </LI> <LI> The bioscaffolds exhibit excellent platform for osteogenic differentiation of pre-osteoblastic cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrodeless coating polypyrrole on chitosan grafted polyurethane with functionalized multiwall carbon nanotubes electrospun scaffold for nerve tissue engineering

Shrestha, Sita,Shrestha, Bishnu Kumar,Kim, Jeong In,Won Ko, Sung,Park, Chan Hee,Kim, Cheol Sang Elsevier 2018 Carbon Vol.136 No.-

<P><B>Abstract</B></P> <P>Herein, we engineered a self-electrical stimulated double-layered nerve guidance conduit (NGC) assembled from electrospun mats with an aligned oriented inward layer covered with a random oriented outer layer. The biomimetic NGC can be achieved from chitosan grafted polyurethane with well-dispersed functionalized multiwall carbon nanotubes (<I>f</I>MWCNTs) nanofibrous mats after a uniform coating of polypyrrole (PPy). The structural framework of interconnected NGC exhibited cellular biomaterial interface and improved the physicochemical properties, including electrical conductivity, mechanical strength, and cytocompatibility, serving as natural hosting substrate to natural extracellular matrices (ECM) for vital roles in nerve tissue engineering. The regrowth, proliferation, and migration, of Schwann cells (S42) and the differentiation of rat pheochromocytoma cells (PC12) were greatly accelerated on the aligned oriented mats as compared to the randomly oriented mats during <I>in vitro</I> cell cultures. The morphology of the spontaneous outgrowth and phenotype of neurite bundles were preferentially guided along the axis of the aligned oriented nanofibers, which maintains a strong adaptability in axonal regeneration. In addition, the differentiation of PC12 cells cultured on as-fabricated NGCs were evaluated from cDNA gene expression. It is hoped that the results will contribute to the efficient application of designed NGCs and can be used in therapeutic strategies for treating injured sites and stimulate recovery from substantial damage to nerve cells.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

In situ synthesis of cylindrical spongy polypyrrole doped protonated graphitic carbon nitride for cholesterol sensing application

Shrestha, Bishnu Kumar,Ahmad, Rafiq,Shrestha, Sita,Park, Chan Hee,Kim, Cheol Sang Elsevier 2017 Biosensors & bioelectronics Vol.94 No.-

<P><B>Abstract</B></P> <P>Herein, we demonstrate the exfoliation of bulk graphitic carbon nitrides (g-C<SUB>3</SUB>N<SUB>4</SUB>) into ultra-thin (~3.4nm) two-dimensional (2D) nanosheets and their functionalization with proton (g-C<SUB>3</SUB>N<SUB>4</SUB>H<SUP>+</SUP>). The layered semiconductor g-C<SUB>3</SUB>N<SUB>4</SUB>H<SUP>+</SUP> nanosheets were doped with cylindrical spongy shaped polypyrrole (CSPPy-g-C<SUB>3</SUB>N<SUB>4</SUB>H<SUP>+</SUP>) using chemical polymerization method. The as-prepared nanohybrid composite was utilized to fabricate cholesterol biosensors after immobilization of cholesterol oxidase (ChOx) at physiological pH. Large specific surface area and positive charge nature of CSPPy-g-C<SUB>3</SUB>N<SUB>4</SUB>H<SUP>+</SUP> composite has tendency to generate strong electrostatic attraction with negatively charged ChOx, and as a result they formed stable bionanohybrid composite with high enzyme loading. A detailed electrochemical characterization of as-fabricated biosensor electrode (ChOx-CSPPy-g-C<SUB>3</SUB>N<SUB>4</SUB>H<SUP>+</SUP>/GCE) exhibited high-sensitivity (645.7 µAmM<SUP>−1</SUP> cm<SUP>−2</SUP>) in wide-linear range of 0.02–5.0mM, low detection limit (8.0μM), fast response time (~3s), long-term stability, and good selectivity during cholesterol detection. To the best of our knowledge, this novel nanocomposite was utilized for the first time for cholesterol biosensor fabrication that resulted in high sensing performance. Hence, this approach opens a new prospective to utilize CSPPy-g-C<SUB>3</SUB>N<SUB>4</SUB>H<SUP>+</SUP> composite as cost-effective, biocompatible, eco-friendly, and superior electrocatalytic as well as electroconductive having great application potentials that could pave the ways to explore many other new sensors fabrication and biomedical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Preparation of ultrathin 2D nanosheets of graphite carbon nitride and their protonation. </LI> <LI> Doping of engineered g-C<SUB>3</SUB>N<SUB>4</SUB>H<SUP>+</SUP> nanosheets with cylindrical spongy shaped polypyrrole. </LI> <LI> ChOx immobilization on CSPPy-g-C<SUB>3</SUB>N<SUB>4</SUB>H<SUP>+</SUP> nanohybrid composite to fabricate cholesterol biosensor. </LI> <LI> The biosensor is highly sensitive and reproducible for cholesterol detection. </LI> <LI> The biosensor was applied for the cholesterol detection in human serum samples successfully. </LI> </UL> </P>

A conducting neural interface of polyurethane/silk-<i>f</i>unctionalized multiwall carbon nanotubes with enhanced mechanical strength for neuroregeneration

Shrestha, Sita,Shrestha, Bishnu Kumar,Lee, Joshua,Joong, Oh Kwang,Kim, Beom-Su,Park, Chan Hee,Kim, Cheol Sang Elsevier S.A. 2019 Materials Science and Engineering C Vol. No.

<P><B>Abstract</B></P> <P>A fibrous scaffold, fully assimilating polyurethane (PU) and silk fibroin associated with functionalized multi-walled carbon nanotubes (<I>f</I>MWCNTs) was developed by electrospinning technique. Herein, we engineered the PU/Silk fibroin-<I>f</I>MWCNTs-based biomaterial that shows great promise as electrospun scaffolds for neuronal growth and differentiation, because of its unique mechanical properties, hydrophilicity, and biodegradability, with outstanding biocompatibility in nerve tissue engineering. The morphology and structural properties of the scaffolds were studied using various techniques. In particular, the presence of <I>f</I>MWCNTs enhances the electrical conductivity and plausible absorption of sufficient extracellular matrix (ECM). The <I>in vitro</I> tests revealed that the aligned scaffolds (PU/Silk-<I>f</I>MWCNTs) significantly stimulated the growth and proliferation of Schwann cells (S42), together with the differentiation and spontaneous neurite outgrowth of rat pheochromocytoma (PC12) cells that were particularly guided along the axis of fiber alignment. The conductive PU/Silk-<I>f</I>MWCNTs scaffold significantly improves neural expression <I>in vitro</I> with successful axonal regrowth, which was confirmed by immunocytochemistry and qRT-PCR analysis. Inspired by the comprehensive experimental results, the <I>f</I>MWCNTs-based scaffold affords new insight into nerve-guided conduit design from both conductive and protein rich standpoints, and opens a new perspective on peripheral nerve restoration in preclinical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Polyurethane-silk/multiwall carbon nanotubes based aligned electrospun scaffold was fabricated. </LI> <LI> A protein rich biomaterial showed high mechanical strength and good electrical conductivity. </LI> <LI> PC12 cells are well proliferated and differentiated on scaffold along with fibers orientation. </LI> <LI> The scaffold exhibited strong bioactivity, suited for <I>in vitro</I> nerve cell regeneration. </LI> </UL> </P>

π-Conjugated polyaniline-assisted flexible titania nanotubes with controlled surface morphology as regenerative medicine in nerve cell growth

Shrestha, Bishnu Kumar,Shrestha, Sita,Baral, Ek Raj,Lee, Ji Yeon,Kim, Beom-Su,Park, Chan Hee,Kim, Cheol Sang Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.360 No.-

<P><B>Abstract</B></P> <P>Biologically active conjugated polymers, for example polyaniline (PANI), have drawn attention as emerging materials for applications in bio-medical implant devices, due to their inherent abilities with regard to charge-carrier properties, and their ability to immobilize biomolecules or proteins. Herein, we report an electrocoating of PANI on titania nanotubes (TNTs) via electrochemical oxidation of aniline with PANI layers of appropriate thickness (∼274 nm). Uniform titanium oxide nanotubes were first developed from titanium (Ti) foil through an anodization process, followed by calcination to obtain high purity TNTs vertically aligned on a Ti substrate. These had a large surface area, controllable tube height and diameter, and were highly biocompatible, and doping with PANI further improved their properties, like being antibacterial, having a lower charge transfer resistance (22.51 Ω) and strong anti-corrosion behavior (<I>E<SUB>corr</SUB> </I> ∼ − 184 mV, <I>I<SUB>corr</SUB> </I> ∼ 9.7 × 10<SUP>−7</SUP> Amp). <I>In vitro</I> experiments revealed that the cellular functions of PC12 and S42 cells on TNTs-PANI scaffolds show characteristic improvement in proliferation and differentiation owning to approach neuronal cells activation associated with axonal growth and migration in the peripheral nervous system (PNS). Thus, the flexible bioactive substrate is capable of stimulating neuronal cells, and can inspire neural transduction through direct neural interfaces.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A highly conductive electroactive polyaniline (PANI) was electrodeposited uniformly on titania nanotubes (TNTs) substrate. </LI> <LI> Titania nanotubes-polyaniline (TNTs-PANI) showed antibacterial activity and corrosion resistivity. </LI> <LI> The biointerface TNTs-PANI was used as basal substrate for PC12 cells regeneration and differentiation. </LI> <LI> The flexible TNTs-PANI substrate accelerated the neurites outgrowth of PC12 cells. </LI> </UL> </P>

A controlled surface geometry of polyaniline doped titania nanotubes biointerface for accelerating MC3T3-E1 cells growth in bone tissue engineering

Bhattarai, Deval Prasad,Shrestha, Sita,Shrestha, Bishnu Kumar,Park, Chan Hee,Kim, Cheol Sang Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.350 No.-

<P><B>Abstract</B></P> <P>In this work, titanium oxide nanotubes (TNTs) have been developed via electrochemical anodization process, followed by potentiostatic electropolymerization of aniline monomer to achieve TNTs coated polyaniline (PANI) substrate using cyclic voltammetry method at low temperature. Prior to PANI decoration, crystallinity of titanium oxide nanotubes (TNTs) was obtained by annealing the substrate at 420 °C for two hours. The physicochemical characterization of the as-prepared TNTs and TNTs/PANI were analyzed using FE-SEM, AFM, XRD and FT-IR techniques. A coating of PANI forms a sheath around the nanotubes and protects them from metallic corrosion. Large surface area to volume ratio of TNTs showed improved properties in biocompatibility, thermal stability, electrical conductivity, biomineralization and hydrophilicity after coating with PANI, an electroactive conducting polymer. In addition, the TNTs/PANI exhibited an effective platform to enhance attachment, development and proliferation of preosteoblast (MC3T3-E1) cells which opens a new avenue in the realm of bone tissue engineering. The cells’ morphology to their surrounding topography, development, or proliferation, and osteogenic-related markers (such as ALP increased level, collagen type I secretion) were also analysed. Such types of surface modification tailoring on titanium nanotubes could offer a potential and a promising scaffold material for biomedical implantation in bone tissue engineering.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A uniform surface topography of titanium nanotubes (TNTs) were fabricated through anodization. </LI> <LI> The TNTs were coated with polyaniline (PANI) via cyclic voltammetric technique. </LI> <LI> The bioinspired TNTs/PANI showed an effective antibacterial property. </LI> <LI> Highly biocompatible TNTs/PANI scaffolds enhanced the proliferation of pre-osteoblast cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Engineered nanostructure fibrous cell-laden biointerfaces integrating Fe3O4/SrO2-fMWCNTs induce osteogenesis and anti-bacterial effect

KANDELRUPESH,장세림,Upasana Ghimire,Sita Shrestha,Bishnu Kumar Shrestha,박찬희,김철생 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-

Improving biomechanical and biochemical properties of tissue-engineered scaffolds akin to those ofnative stem-cell niches can effectively regenerate tissues. Bio-ceramic nanomaterials integrated porousscaffolds can be employed to promote bone cell proliferation and contribute to their translational value. Here, we successfully developed highly conductive fibrous scaffolds of polyurethane (PU) integratingFe3O4/SrO2 nanoparticles (NPs) in association with functionalized multiwall carbon nanotubes(fMWCNTs). The engineered scaffold of PU-Fe3O4/SrO2-fMWCNTs with 0.4 wt.% of NPs showed synergisticeffects on physicochemical and biological performances. The porous scaffold showed superior interfacialbiocompatibility, antibacterial properties, and load-bearing ability. Results of in vitro, including ALPactivity, collagen-I, and ARS staining of MC3T3-E1 cells confirmed that the scaffold provided a favorablemicroenvironment with a prominent effect on the growth, proliferation, and differentiation of MC3T3-E1cells. Furthermore, the up-regulated osteogenic protein expression of MC3T3-E1 cells was studied byqRT-PCR, and Western blotting and found the osteoblastic activity accelerated due to the enhanced mineralizationof PU-Fe3O4/SrO2-fMWCNTs (0.4 wt.%). Together, our findings suggest these scaffolds withimproved cell-interface compatibility exhibit osteoinductivity that could become a novelnanomaterial-based tissue construct as a therapeutic strategy for bone cell regeneration and bone defectrepair.

Exfoliated nanosheets of Co3O4 webbed with polyaniline nanofibers: A novel composite electrode material for enzymeless glucose sensing application

Mohamed A. Yassin,Bishnu Kumar Shrestha,Rafiq Ahmad,Sita Shrestha,박찬희,김철상 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.73 No.-

A novel glucose biosensor was designed using cobalt oxide (Co3O4) nanosheets patterned byp-conjugated polyaniline nanofibers (PANINFs). A facile synthesis process was conducted to obtaincost-effective and ecofriendly mesoporous Co3O4@PANINFs hybrid nanomaterial for thefirst time. TheCo3O4@PANINFs on glassy carbon electrode (GCE), working as a biosensor electrode based onelectrochemical technique, showed electrocatalytic activity to glucose with sensitivity of 14.25 mAmM 1cm 2, linear range from (0.1 to 8) mM, minimum detection limit of 0.06 mM, and response time<6 s. Moreover, the biosensor was employed to monitor glucose concentration in human serum sample toprovide effective sensing results.