Direct cell imprint lithography in superconductive carbon black polymer composites: process optimization, characterization and in vitro toxicity analysis.

Cell imprint lithography (CIL) or cell replication plays a vital role in fields like biomimetic smart culture substrates, bone tissue engineering, cell guiding, cell adhesion, tissue engineering, cell microenvironments, tissue microenvironments, cell research, drug delivery, diagnostics, therapeutics and many other applications. Herein we report a new formulation of superconductive carbon black photopolymer composite and its characterization towards a CIL process technique. In this article, we demonstrated an approach of using a carbon nanoparticle-polymer composite (CPC) for patterning cells. It is observed that a 0.3 wt % load of carbon nanoparticles (CNPs) in a carbon polymer mixture (CPM) was optimal for cell-imprint replica fabrication. The electrical resistance of the 3-CPC (0.3 wt %) was reduced by 68% when compared to N-CPC (0 wt %). This method successfully replicated the single cell with sub-organelle scale. The shape of microvesicles, grooves, pores, blebs or microvilli on the cellular surface was patterned clearly. This technique delivers a free-standing cell feature substrate. In vitro evaluation of the polymer demonstrated it as an ideal candidate for biomimetic biomaterial applications. This approach also finds its application in study based on morphology, especially for drug delivery applications and for investigations based on molecular pathways.

Osteogenic apatite particles by sol-gel assisted electrospraying.

Electrospraying has tremendous potential to prepare submicron to nano size ceramic particles with novel properties. In this study, a sol-gel assisted electrospraying has been used to synthesise phase controlled apatite (hydroxyapatite, HA and calcium deficient hydroxyapatite, CDHA) particles. Variation in particle size was also achieved by controlling the process parameters. The particles were non cytotoxic, induced proliferation of osteoblast-like cells (HOS) and internalised by the cells. Increased alkaline phosphatase, collagen and calcium deposition confirmed the mineralisation of cells. Expression of osteopontin, osteocalcin and alkaline phosphatase genes further ascertained that the particles promoted osteogenic commitment of the rat bone marrow-derived mesenchymal stem cells (rBMSCs). The particles also showed better loading and release of tetracycline drug than accelerated microwave synthesised apatite particles. The methodology for synthesis of ceramic particles may have avenues for a wide range of biomedical applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1941-1954, 2018.

Electrospun 3D composite scaffolds for craniofacial critical size defects.

Critical size defects in the craniofacial region can be effectively treated using three dimensional (3D) composite structures mimicking natural extra cellular matrix (ECM) and incorporated with bioactive ceramics. In this study we have shown that the dynamic liquid bath collector can be used to form electrospun polycaprolactone (PCL)-hydroxyapatite (HA) composite structure as unique 3D scaffold. The structure was found to have three distinct sections (base, stem and head) based on the mechanism of its formation and morphology. The size of the head portion was around 15 mm and was found to vary with the process parameters. Scanning electron microscopy (SEM) analysis revealed that the base had random fibres while the fibres in stem and head sections were aligned but perpendicular to each other. X-ray diffraction (XRD) analysis also showed an increase in the crystallinity index of the fibres from base to head section. Cytotoxicity and cytocompatibility studies using human osteosarcoma (HOS) cells showed good cell adhesion and proliferation indicating the suitability of the 3D structure for craniofacial graft applications.

Electrospun Cytocompatible Polycaprolactone Blend Composite with Enhanced Wettability for Bone Tissue Engineering.

Electrospinning is recently used in tissue engineering due to their excellent ability to mimic the structure of extra cellular matrix (ECM), a prerequisite for creating an optimal microenvironment for cell growth. Electrospun nanofibrous composite scaffolds consisting of polycaprolactone (PCL)/Poly(1,4-butylene adipate-co-polycaprolactam) (PBAPCL) blend with hydroxyapatite (HA) have been fabricated to enhance the wettability and osseointegrative properties. Fourier transform-infrared spectroscopy (FT-IR) confirmed molecular interactions of the polymer blend along with the presence of HA. X-ray diffraction analysis (XRD) indicated semi-crystalline nature of the mat and also the presence of HA in the composite mat. The morphology of the fibres, were analyzed using scanning electron microscopy (SEM) and the diameter was found to be in the range of 400­600 nm. The composite fibers were of larger diameter compared to their polymer counterparts. Improved wettability of the electrospun composite mat has been observed by contact angle analysis. In vitro cell culture studies by Live/Dead assay and MTT using human osteosarcoma (HOS) cells indicated the cytocompatible nature of electrospun mat which was further confirmed by cell adhesion using SEM and Actin-phalloidin staining. Addition of PBAPCL and HA to PCL have a beneficial effect on cell growth and proliferation thereby making the composite, a prospective scaffold for bone tissue engineering applications.

Preparation, characterization and biological evaluation of curcumin loaded alginate aldehyde-gelatin nanogels.

Curcumin, a natural polyphenol exhibits chemopreventive and chemotherapeutic activities towards cancer. In order to improve the bioavailability and therapeutic efficacy, curcumin is encapsulated in alginate aldehyde-gelatin (Alg Ald-Gel) nanogels. Alginate aldehyde-gelatin nanogels are prepared by inverse miniemulsion technique. Physicochemical properties of the curcumin loaded nanogels are evaluated by, Dynamic light scattering (DLS), NMR spectroscopy and Scanning electron microscopy (SEM). Curcumin loaded nanogels show hydrodynamic diameter of 431±8nm and a zeta potential of -36±4mV. The prepared nanogels exhibit an encapsulation efficiency of 72±2%. In vitro drug release studies show a controlled release of curcumin from nanogels over a period of 48h. Hemocompatibility and cytocompatibility of the nanogels are evaluated. Bare nanogels are cytocompatible and curcumin loaded nanogels induce anticancer activity towards MCF-7 cells. In vitro cellular uptake of the curcumin loaded nanogels using confocal laser scanning microscopy (CLSM) confirms the uptake of nanogels in MCF-7 cells. Hence, the developed nanogel system can be a suitable candidate for curcumin delivery to cancer cells.

Galactosylated alginate-curcumin micelles for enhanced delivery of curcumin to hepatocytes.

Galactosylated alginate-curcumin conjugate (LANH2-Alg Ald-Cur) is synthesized for targeted delivery of curcumin to hepatocytes exploiting asialoglycoprotein receptor (ASGPR) on hepatocytes. The synthetic procedure includes oxidation of alginate (Alg), modification of lactobionic acid (LA), grafting of targeting group (modified lactobinic acid, LANH2) and conjugation of curcumin to alginate. Alginate-curcumin conjugate (Alg-Cur) without targeting group is also prepared for the comparison of properties. LANH2-Alg Ald-Cur self assembles to micelle with diameter of 235 ± 5 nm and zeta potential of -29 mV in water. Cytotoxicity analysis demonstrates enhanced toxicity of LANH2-Alg Ald-Cur over Alg-Cur on HepG2 cells. Cellular uptake studies confirm that LANH2-Alg Ald-Cur can selectively recognize HepG2 cells and shows higher internalization than Alg-Cur conjugate. Results indicate that LANH2-Alg Ald-Cur conjugate micelles are suitable candidates for targeted delivery of curcumin to HepG2 cells.

Microgravity as a means to incorporate HepG2 aggregates in polysaccharide-protein hybrid scaffold.

Tissue culture under microgravity provides a venue which promotes cell-cell association while avoiding the detrimental effects of high shear stress. Hepatocytes cultured on carriers or entrapped within matrices under simulated microgravity conditions showed improved cell function and proliferation. In the present study, a new approach was adopted where a non-cell adherent scaffold was incorporated with hepatospheroids (HepG2) under microgravity. Gum arabic (GA) was cross-linked with gelatin (GA-Gel) and collagen (GA-Col) to prepare non-cell adherent scaffolds. Microgravity experiments with GA-Gel and GA-Col indicated that GA-Col is a better substrate compared to GA-Gel. Microgravity experiments of GA-Col scaffolds with HepG2 cells confirmed that the non-adherent surface with porous architecture can incorporate hepatocyte spheroids and maintain liver specific functions. Albumin and urea synthesis of hepatocytes was sustained up to 6 days under microgravity conditions in the presence of GA-Col scaffold. This new approach of using non-cell adherent matrix and microgravity environment for developing biological substitutes will be beneficial in tissue engineering, bioartificial liver devices and in vitro safety assessment of drugs.

Gum arabic-curcumin conjugate micelles with enhanced loading for curcumin delivery to hepatocarcinoma cells.

Curcumin is conjugated to gum arabic, a highly water soluble polysaccharide to enhance the solubility and stability of curcumin. Conjugation of curcumin to gum arabic is confirmed by (1)H NMR, fluorescence and UV spectroscopy studies. The conjugate self assembles to spherical nano-micelles (270 ± 5 nm) spontaneously, when dispersed in aqueous medium. Spherical morphology of the self assembled conjugate is evidenced by field emission scanning electron microscopy and transmission electron microscopy. The self assembly of the amphiphilic conjugate into micelle in aqueous medium significantly enhances the solubility (900 fold of that of free curcumin) and stability of curcumin in physiological pH. The anticancer activity of the conjugate micelles is found to be higher in human hepatocellular carcinoma (HepG2) cells than in human breast carcinoma (MCF-7) cells. The conjugate exhibits enhanced accumulation and toxicity in HepG2 cells due to the targeting efficiency of the galactose groups present in gum arabic.

Galactosylated pullulan-curcumin conjugate micelles for site specific anticancer activity to hepatocarcinoma cells.

Galactosylated pullulan-curcumin conjugate (LANH2-Pu Ald-Cur SA) is developed for target specific delivery of curcumin to hepatocarcinoma cells by five step synthetic strategy, which includes oxidation of pullulan (Pu Ald), introduction of amino group to the targeting ligand (LANH2), grafting of the LANH2 to Pu Ald, modification of curcumin (Cur SA) and conjugation of Cur SA to pullulan. Nongalactosylated pullulan-curcumin conjugate (Pu-Cur SA) is also prepared to compare the enhancement in cytotoxicity offered by the targeting group. Both LANH2-Pu Ald-Cur SA and Pu-Cur SA conjugates could self assemble to micelle in water with hydrodynamic diameters of 355±9nm and 363±10nm, respectively. Both conjugates show spherical morphology and enhance stability of curcumin in physiological pH. Compared to Pu-Cur SA, LANH2-Pu Ald-Cur SA exhibits higher toxicity and internalization towards HepG2 cells. This indicates the enhanced uptake of LANH2-Pu Ald-Cur SA conjugate via ASGPR (asialoglycoprotein receptor) mediated endocytosis into HepG2 cells.

Nanogels based on alginic aldehyde and gelatin by inverse miniemulsion technique: synthesis and characterization.

Nanogels were developed from alginic aldehyde and gelatin by an inverse miniemulsion technique. Stable inverse miniemulsions were prepared by sonication of noncontinuous aqueous phase (mixture of alginic aldehyde and gelatin) in a continuous organic phase (Span 20 dissolved in cyclohexane). Cross-linking occurred between alginic aldehyde (AA) and gelatin (gel) in the presence of borax by Schiff's base reaction during the formation of inverse miniemulsion. The effects of surfactant (Span 20) concentration, volume of the aqueous phase and AA/gel weight ratio on the size of the alginic aldehyde-gelatin (AA-gel) nanoparticles were studied. Nanogels were characterized by DLS, FT-IR spectroscopy, TGA, SEM and TEM. DLS, TEM and SEM studies demonstrated nanosize and spherical morphology of the nanogels. Hemocompatibility and in vitro cytocompatibility analyses of the nanogels proved their nontoxicity. The results indicated the potential of the present nanogel system as a candidate for drug- and gene-delivery applications.

Evaluation of polypropylene hollow-fiber prototype bioreactor for bioartificial liver.

Hepatocytes in high density are a requisite for the functional performance of complex devices such as bioartificial liver (BAL). In addition to high cell number, efficient mass transfer is also a key parameter in such devices. High-density culture of cells and efficient mass transfer can be achieved in BAL with hollow-fiber-based bioreactors. Even though different types of hollow fibers have been tried in a BAL, prospects of using polypropylene hollow fibers are not well evaluated. In this study, a prototype of bioreactor with polypropylene hollow fibers was fabricated and evaluated for cytotoxicity and hepatocyte function. High density of HepG2/adult hepatocyte cultures was used to evaluate polypropylene hollow fiber to support the biochemical activities (albumin and urea production), ammonia detoxification, and gene expression and to provide effective oxygenation. The results confirmed that a polypropylene hollow-fiber prototype bioreactor is able to provide efficient oxygenation and supported hepatocyte functions in a high-density culture.