Enhanced Cell Attachment Research Articles

Type I collagen concentration affects neurite outgrowth of adult rat DRG explants by altering mechanical properties of hydrogels

Type I collagen is a predominant fibrous protein that makes up the extracellular matrix. Collagen enhances cell attachment and is commonly used in three-dimensional culture systems, to mimic the native extracellular environment, for primary sensory neurons such as dorsal root ganglia (DRG). However, the effects of collagen concentration on adult rat DRG neurite growth have not been assessed in a physiologically relevant, three-dimensional culture. This study focuses on the effects of type I collagen used in a methacrylated hyaluronic acid (MAHA)-laminin-collagen gel (triple gel) on primary adult rat DRG explants in vitro. DRGs were cultured in triple gels, and the neurite lengths and number of support cells were quantified. Increased collagen concentration significantly reduced neurite length but did not affect support cell counts. Mechanical properties, fiber diameter, diffusivity, and mesh size of the triple gels with varying collagen concentration were characterized to further understand the effects of type I collagen on hydrogel property that may affect adult rat DRG explants. Gel stiffness significantly increased as collagen concentration increased and is correlated to DRG neurite length. Collagen concentration also significantly impacted fiber diameter but there was no correlation with DRG neurite length. Increasing collagen concentration had no significant effect on mesh size and diffusivity of the hydrogel. These data suggest that increasing type I collagen minimizes adult rat DRG explant growth in vitro while raising gel stiffness. This knowledge can help develop more robust 3D culture platforms to study sensory neuron growth and design biomaterials for nerve regeneration applications.

Enhancement of cell attachment on Ti6Al4V via surface modifications using pulsed laser surface melting

The surface topography of biomedical implants made of Ti6Al4V significantly impacts cell attachment. This work aims to modify the surface topography of the Ti6Al4V surface using pulse laser surface melting (pLSM) to enhance fibroblast cell attachment. In pLSM, short laser pulses irradiate the surface resulting in localised melting and creating new features upon resolidification. Thus, surfaces are modified without the addition or removal of material. The effect of laser pulse duration and hatch spacing on the attachment of NIH3T3 fibroblast cells is examined in this study. The cells were cultured on the pLSM-textured surfaces and two control surfaces, viz., as-received and manually polished, and the results were studied after 24 h of cell culture using fluorescence microscopy. pLSM-textured surfaces showed improved cell attachment compared to the control surfaces. The surface textured with a 10 μs pulse duration and 75 % hatch spacing showed 395 % and 91 % improvement in attached cell density compared to the as-received surface and manually polished surface, respectively, because the induced feature size was comparable to the size of NIH3T3 fibroblast cells. Additionally, the periodic textures developed by pLSM resulted in a homogenous distribution of the cells across the area.

Evaluation of the effects of zein incorporation on physical, mechanical, and biological properties of polyhydroxybutyrate electrospun scaffold for bone tissue engineering applications

Materials and fabrication methods significantly influence the scaffold's final features in tissue engineering. This study aimed to blend zein with polyhydroxybutyrate (PHB) at 5, 10, and 15 wt%, fabricate scaffolds using electrospinning, and then characterize them. SEM and mechanical analyses identified the scaffold with 10 wt% zein (PHB-10Z) as the optimal sample. Incorporating 10 wt% zein reduced fiber diameter from 894 ± 122 to 531 ± 42 nm while increasing ultimate tensile strength and elongation at break by approximately 53 % and 70 %, respectively. FTIR proved zein's presence in the scaffolds and possible hydrogen bonding with PHB. TGA confirmed the miscibility of polymers. DSC and XRD analyses indicated lower crystallinity for the PHB-10Z than for PHB. AFM evaluation indicated a rougher surface for the PHB-10Z in comparison to PHB. The PHB-10Z demonstrated a more hydrophobic surface and less weight loss after 100 days of degradation in PBS than PHB. The free radical scavenging assay exhibited antioxidant activity for the zein-containing scaffold. Eventually, enhanced cell attachment, viability, and differentiation in the PHB-10Z scaffold drawn from SEM, MTT, ALP activity, and Alizarin red staining of MG-63 cells confirmed that PHB-zein electrospun scaffold is a potent candidate for bone tissue engineering applications.

Preparation of thermosensitive PNIPAm- based copolymers with tertiary amino and hydroxyl monomer for cell attachment and detachment study

Thermo-responsive microcarriers are essential for large-scale expansion of anchorage-dependent cells in a suspension culture. In this study, the authors prepared four different N-isopropylacrylamide (NIPAm)-based thermosensitive copolymers by copolymerizing with N-hydroxyethyl acrylamide (HEAA), 2-Hydroxyethyl methacrylate (HEMA), 2-(Diethylamino) ethylmethacrylate (DEAEMA), and 2-(Dimethylamino) ethylmethacylate (DMAEMA) through free radical polymerization (FRP) and used them for surface modification of Cytodex-3 microcarrier. The thermosensitive characteristic of the copolymers enabled microcarriers to attach and detach cells in response to temperature changes. Herein, NIH 3T3 cells were used as a model cell line and it was found that the cells' adhesion rate on Cytodex-3 microcarriers modified with different formulations of thermosensitive copolymers was greater than unmodified microcarriers. The microcarriers coated with 5 wt% of the copolymer showed better cell attachment than 3 wt% and 10 wt% copolymer coated microcarriers. Particularly, 5 wt% P(NIPAm-5% HEMA) copolymer coated microcarriers showed excellent cell attachment than other formulations. More importantly, as the temperature was reduced to 4 °C, the cells cultured on copolymer modified microcarriers were completely detached as a cell sheet from it withoutproteolytic enzymetreatment. Besides preserving the functionality and integrity of cellular structures, the thermal-induced detachment of cells from modified microcarriers was much higher (∼9.9 x 104 cells/mL) than cells detached from the original Cytodex-3 (∼7.5x103 cells/mL) in 1 h at 4 °C. Therefore, this study verified that microcarriers modified with thermosensitive copolymers exhibited enhanced cell attachment and detachment with temperature change, while maintaining cell functionality, thereby providing adequate number of viable cells for large scale production.

BIOSCAFFOLD FROM MOUSE EMBRYONIC FIBROBLAST MAINTAINS THE PLURIPOTENCY OF MOUSE EMBRYONIC STEM CELLS

Cell culture using a 3D method provides Various cell culture strategies have been developed using synthetic or biological materials; most existing publications use many reagents. Bioscaffold from mouse embryonic fibroblast (MEF) enhances cell attachment, interaction, and production of growth factors. Since bioscaffolds could maintain and stimulate pluripotency of stem cells, we conducted this study to prove bioscaffold function. Bioscaffold was prepared from MEF cultured in DMEM complete medium supplemented with dextran sulfate and L-ascorbic acid to increase extracellular matrix production. This medium acts as an embryo stem cell (ESC) culture medium. We used a Tali-cytometer to identify and quantify stem cells based on Sox2 and Oct4 proteins, markers of stemness. ESC culture using bioscaffold maintained the pluripotency of ESC as indicated by the presence of Oct 4 and Sox2 as ESC markers compared to MEF culture. From this research, the bioscaffold from MEF can be developed as media for ESC to improve propagation. Furthermore, it is a model for tissue engineering and in vitro organ development.

Hierarchical and urchin-like chitosan/hydroxyapatite microspheres as drug-laden cell carriers

Biopolymer/hydroxyapatite (HAp) composites are one type of the most promising materials for a variety of biomedical applications. In this study, hierarchical and urchin-like chitosan/HAp nanowire (HU-CS/HAp NW) microspheres were for the first time synthesized by in situ hydrothermal treatment of chitosan/HAp (CS/HAp) microspheres in the acetic acid solution. The results indicate that HU-CS/HAp NW microspheres were spherical in morphology with a diameter of 100–300 μm. Their surface was mainly constructed by numerous HAp NWs with the diameter of 80–120 nm and showed a hierarchical and urchin-like nanofibrous architecture. It was found that the acidic hydrothermal treatment caused an in situ conversion of HAp NPs to HAp NWs. In vitro biocompatible evaluation indicates that HU-CS/HAp NW microspheres showed an enhanced cell attachment and proliferation due to the presence of hierarchical and urchin-like architecture. Furthermore, HU-CS/HAp NW microspheres showed a good adsorption capacity for tetracycline hydrochloride (model drug, one of the most representative antibiotics) with a higher adsorption capacity than CS/HAp microspheres and well maintained their antibacterial efficacy to inhibit the growth of bacteria: Escherichia coli and Staphylococcus aureus. Thus, the present HU-CS/HAp NW microspheres would be applicable as novel drug-laden cell carriers.

Facile synthesis of nanofibrous and hollow titania microspheres as drug‐laden cell carriers

AbstractMicrospheres are one type of promising cell‐supporting matrices. However, the synthesis of nanofibrous and hollow microspheres as drug‐laden cell carriers is still a great challenge. Here, the nanofibrous and hollow titania nanowire (NH‐TiNW) microspheres were synthesized by in situ alkali hydrothermal treatment of hollow titania (H‐Ti) microspheres, and their microstructure, biocompatibility, and drug delivery property were evaluated. By controlling hydrothermal temperature from 80 to 120°C and hydrothermal time from 1 to 4 h, the surface of H‐Ti microspheres was controllably tailored with nanoparticles and NWs. The results showed that NH‐TiNW microspheres were spherical in morphology with a diameter of 100–200 µm, hierarchically assembled by numerous TiNWs with the diameter of 10–20 nm, and possessed a nanofibrous and hollow structure. In vitro biocompatibility evaluation showed that NH‐TiNW microspheres presented an enhanced cell attachment and proliferation compared with H‐Ti microspheres due to the presence of the nanofibrous surface. Drug delivery evaluation showed that NH‐TiNW microspheres strongly adsorbed tetracycline hydrochloride (one type of antibiotic, model drug) with a loading efficiency of 81.5% ± 1% due to the presence of the nanofibrous and hollow structure and also effectively maintained the biological efficiency of the loaded drugs to inhibit the growth of bacteria.

Overexpression of quorum sensing genes in Acidithiobacillus ferrooxidans enhances cell attachment and covellite bioleaching

Cell adhesion is generally a prerequisite to the microbial bioleaching of sulfide minerals, and surface biofilm formation is modulated via quorum sensing (QS) communication. We explored the impact of the overexpression of endogenous QS machinery on the covellite bioleaching capabilities of Acidithiobacillus ferrooxidans, a representative acidophilic chemolithoautotrophic bacterium. Cells were engineered to overexpress the endogenous qs-I operon or just the afeI gene under control of the tac promoter. Both strains exhibited increased transcriptional gene expression of afeI and improved cell adhesion to covellite, including increased production of extracellular polymeric substances and increased biofilm formation. Under low iron conditions, the improved bioleaching of covellite was more evident when afeI was overexpressed alone as compared to the native operon. These observations demonstrate the potential for the genetic modulation of QS as a mechanism for increasing the bioleaching efficiency of covellite, and potentially other copper sulfide minerals.

Green Biodegradable Polylactide-Based Polyurethane Triblock Copolymers Reinforced with Cellulose Nanowhiskers

A novel series of biodegradable polylactide-based triblock polyurethane (TBPU) copolymers covering a wide range of molecular weights and compositions were synthesized for potential use in biomedical applications. This new class of copolymers showed tailored mechanical properties, improved degradation rates, and enhanced cell attachment potential compared to polylactide homopolymer. Triblock copolymers, (TB) PL-PEG-PL, of different compositions were first synthesized from lactide and polyethylene glycol (PEG) via ring-opening polymerization in the presence of tin octoate as the catalyst. After which, polycaprolactone diol (PCL-diol) reacted with TB copolymers using 1,4-butane diisocyanate (BDI) as a nontoxic chain extender to form the final TBPUs. The final composition, molecular weight, thermal properties, hydrophilicity, and biodegradation rates of the obtained TB copolymers, and the corresponding TBPUs were characterized using 1H-NMR, GPC, FTIR, DSC, and SEM, and contact angle measurements. Results obtained from the lower molecular weight series of TBPUs demonstrated potential use in drug delivery and imaging contrast agents due to their high hydrophilicity and degradation rates. On the other hand, the higher molecular weight series of TBPUs exhibited improved hydrophilicity and degradation rates compared to PL-homopolymer. Moreover, they displayed improved tailored mechanical properties suitable for utilization as bone cement, or in regeneration medicinal applications of cartilage, trabecular, and cancellous bone implants. Furthermore, the polymer nanocomposites obtained by reinforcing the TBPU3 matrix with 7% (w/w) bacterial cellulose nanowhiskers (BCNW) displayed a ~16% increase in tensile strength, and 330% in % elongation compared with PL-homo polymer.

The Influence of Scaffold Interfaces Containing Natural Bone Elements on Bone Tissue Engineering Applications

Bone has the capacity to repair damage and reproduce itself, but if the defect is too large, a scaffold is needed to promote regeneration. Recently, researchers have developed numerous approaches to promote bone reformation, such as the direct delivery of bioactive molecules, guided tissue regeneration membranes, and creating osteoinduction/osteoconduction surfaces. The surface of a medical device is the first contact area for a biological system; therefore, the interactions between biological fluids and the surface of the implant determine the performance of the implant. Well-designed surface physical and chemical properties, such as topography, net charge, components, and hydrophilicity, enhance cell attachment and proliferation. Various surface modification technologies and methods have been studied to enhance cellular expression. This review selects scaffold materials that are FDA-approved and have been widely used in the clinic and focuses on recent studies of surface modification with hydroxyapatites and collagen, which are the main components of the bone matrix, for the enhancement of bone regrowth.

Surface functionalization of gallium nitride for biomedical implant applications

GaN is an aqueous and chemically stable material that has demonstrated biocompatibility with potential in biomedical engineering and offers enormous opportunities to tailor its inherent surface properties and promote efficient biomolecule adhesion with targeted functionalities. In this article, functionalization of GaN surfaces via a three-step process to enhance cell attachment and its effective utilization in in-vivo and in-vitro applications is reported. The morphology and surface chemistry of GaN surfaces were modified using sodium hydroxide and 3-aminopropyltriethoxy silane followed via bioconjugation with type 1-human collagen (T1HC), and the changes in chemical states, morphology, wettability, pH, and aqueous stability were investigated. Further, cell culture studies using human periodontal ligament fibroblast (HPdlF) cells were undertaken. The proliferation and adhesion/survivability studies at different time intervals on functionalized GaN surfaces were performed and analyzed via MTT Assay and SEM evaluation. It has been observed that the hydroxyl species and protonated amines promotes the adhesion of the silane coupling agent and human collagen, which remains stable under standard cell culture media. The chemically functionalized T1HC bio-conjugated GaN surfaces display excellent cell culture properties with complete cell adhesion and viability of ∼ 95 %. The research revealed that chemically functionalized GaN might be useful in various procedures where integrating soft tissues with implant surfaces is crucial.

Modification of Graphite Sheet Anode with Iron (II, III) Oxide-Carbon Dots for Enhancing the Performance of Microbial Fuel Cell

The present study explores the use of carbon dots coated with Iron (II, III) oxide (Fe3O4) for its application as an anode in microbial fuel cells (MFC). Fe3O4@PSA-C was synthesized using a hydrothermal-assisted probe sonication method. Nanoparticles were characterized with XRD, SEM, FTIR, and RAMAN Spectroscopy. Different concentrations of Fe3O4- carbon dots (0.25, 0.5, 0.75, and 1 mg/cm2) were coated onto the graphite sheets (Fe3O4@PSA-C), and their performance in MFC was evaluated. Cyclic voltammetry (CV) of Fe3O4@PSA-C (1 mg/cm2) modified anode indicated oxidation peaks at −0.26 mV and +0.16 mV, respectively, with peak currents of 7.7 mA and 8.1 mA. The fluxes of these anodes were much higher than those of other low-concentration Fe3O4@PSA-C modified anodes and the bare graphite sheet anode. The maximum power density (Pmax) was observed in MFC with a 1 mg/cm2 concentration of Fe3O4@PSA-C was 440.01 mW/m2, 1.54 times higher than MFCs using bare graphite sheet anode (285.01 mW/m2). The elevated interaction area of carbon dots permits pervasive Fe3O4 crystallization providing enhanced cell attachment capability of the anode, boosting the biocompatibility of Fe3O4@PSA-C. This significantly improved the performance of the MFC, making Fe3O4@PSA-C modified graphite sheets a good choice as an anode for its application in MFC.

Bioinspired gelatin nano-film implanted into composite scaffold exhibiting both expandable adhesion and enhanced proliferation

Tissue engineering technology provides a new treatment to the cartilage damage. Recent progress has focused on coating strategies with the printed scaffold surface, using various materials such as bioactive nanocomposites. However, the fracture and exfoliation of printed scaffolds remain challenges due to their poor adhesion on smooth substrates. These limitations can be offset by developing a versatile film. Here, inspired by the mechanism of the wet adhesion of snails, we introduced a biomimetic nanoscale gelatin film between a smooth conductive slide and a scaffold, which enhanced early cell adhesion rates through water absorption, swelling and adhesion. A bionic technique of preparing gelatin nanofilms and PVP/PCL 3D scaffolds, which involved E-Jet atomization deposition and E-Jet printing techniques based on the electrohydrodynamic effect, was investigated. It is found that the composite scaffold with 400 nm gelatin nanofilm significantly enhances cell attachment (from 62 % to 87 %) and proliferation (increased 6.5 times in 7 days). Collectively, this study highlights the combination of biomimetic nanoscale adhesive film in promoting cell adhesion and cartilage differentiation, which benefiting from water absorption and swelling of gelatin nanofilm. This work provides a new idea for the potential application in the orthopedics field.

Influence of strontium and niobium on the physical and biological performance of hydroxyapatite as a bioactive coating on implant materials

The coating of hydroxyapatite (HAP) on the surface of bio-inert metallic implants to augment their bioactivity is in use for the last two decades. Substitution of various materials in HAP further improves the functionality of these coatings. We demonstrate coating of Ti6Al4V alloy sheets with strontium and niobium reinforced HAP using microwave (MW) irradiation technique. Physical characterization revealed, uniform semicrystalline hydroxyapatite coating with enhanced surface roughness and microhardness. The increased surface roughness was accompanied by higher wettability and more protein adsorption. Electrochemical corrosion assessment showed a dramatic increase in corrosion potential and a noticeable decline in corrosion current density suggesting an enhanced anticorrosive behaviour. These implants also exhibited improved hemocompatibility and bacteriostatic properties. Cell viability and confocal microscopy studies of the coated samples showed enhanced cell attachment on the surface. We propose microwave irradiation as a fast and hassle-free alternative for one-pot synthesis and deposition of ionic substituted HAP on metallic implants.

Thermo/redox-responsive dissolvable gelatin-based microsphere for efficient cell harvesting during 3D cell culturing.

The use of microspheres for culturing adherent cells has been proven as an important method, allowing for obtaining adequate number of cells in limited space and volume of medium for the intended cell-based medical applications. However, the use of proteolytic enzymes for cell harvesting from the microsphere resulted in cell damage and loss of functionality. Therefore, in this study, we developed a novel redox/thermo-responsive dissolvable gelatin-based microsphere for successful cell proliferation and harvesting adequate high-quality cells using non-enzymatic cell detachment methods. Initially, a redox-induced dissolvable gelatin-based microsphere was successfully prepared using disulfide bonds as crosslinking agent, firmly stabilizing gelatin networks and forming a stable microsphere at physiological temperature. The optimized concentration of the crosslinking agent was 1.2mM, which kept the microsphere stable for >120h. The microsphere was then coated with PNIPAm-ALA copolymer via physical or chemical means, resulting in a positively charged thermosensitive surface. The positive charge derived from ALA in PNIPAm-ALA copolymer enhanced cell attachment, while the thermosensitive property of the copolymer enabled for temperature induced cell harvesting. When the temperature dropped below the LCST value of PNIPAm-ALA5 (33.4°C), the copolymer swelled and became more hydrophilic, allowing cells to be readily separated. The addition of reducing agents such as GSH, DTT and L-cysteine resulted in further cleavage of the disulfide bond in the microsphere and dissolution of the microsphere for complete cell detachment. Interestingly, cell attachment and proliferation were enhanced on microspheres coated with PNIPAm-ALA5 using diselenide as a crosslinking agent, and complete cell detachment was occurred within 15min after adding 25mM DTT followed by lowering the temperature (4°C). Therefore, the microsphere fabricated in this study was worthwhile for non-enzymatic cell detachment and has the potential to be used for cell expansion and harvesting adequate live cells of high quality and functionality for tissue engineering or cell therapy.

Fabrication of "electroactive cells" using bio-inspired polydopamine-derived carbon nanoparticles for manipulation of cells with electrical stimulation.

In this study, we report some bio-inspired carbon nanoparticles (CNPs) that exhibit high fluorescence quantum yields, good conductivity, excellent dispersion in aqueous solution, high cell-uptake efficiency, and no cytotoxicity as well. We were inspired by mussels’ adhesive components to synthesize polydopamine nanoparticles and then use a carbonization process to prepare fluorescent CNPs. Using some surfactants, we could control the sizes of CNPs and increase their dispersion in water. Fluorescence spectroscopy confirmed the excitation of CNPs at 360 nm and emission of blue light with a 400–450 nm wavelength. High quantum yields of greater than 20% were also measured. Transmission electron microscopy proved that the addition of surfactants could shrink particles to several nanometers in size. The fluorescent and conductive CNPs were applied to stain L929 fibroblast cells in vitro, finding no harmful effects on cells. Due to the polydopamine-derived CNPs’ good electrical, fluorescent, and biocompatible response, we designed a platform to manipulate the cells after endocytosis of conductive CNPs to observe the effects of electrical stimulation on cell attachment, cell growth, and cell death. The nanoparticles endocytosed by cells seemed more easily attracted to the electric field, leading to enhanced cell attachment and growth. Therefore, CNP uptake can increase the attachment of cells onto a conductive plate electrode in a short time (within 10 min at 4°C). When the source of the electric field was changed to rod electrodes in the medium, cells that had been pre-adsorbed onto a non-conductive plate were desorbed from the plate and destroyed. Therefore, addition of CNPs during cell incubation can allow control of cell growth and death via manipulation of electric fields.

A vitronectin-derived dimeric peptide suppresses osteoclastogenesis by binding to c-Fms and inhibiting M-CSF signaling

Vitronectin is an abundant multifunctional glycoprotein found in serum, the extracellular matrix, and bone, and is involved in diverse physiological processes. Here, we developed a new bioactive dimeric peptide (VnP-8-DN1 dimer) from a human vitronectin-derived motif (IDAAFTRINCQG; residues 206–217; VnP-8) via removal of an isoleucine residue at the N-terminus of VnP-8 and spontaneous air oxidation. The VnP-8-DN1 dimer potently enhanced cell attachment activity, and this activity was mediated by binding to cellular heparan sulfate proteoglycan receptors. Moreover, the VnP-8-DN1 dimer suppressed osteoclast differentiation by blocking the early stage of osteoclastogenesis induced by macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL). Furthermore, the VnP-8-DN1 dimer decreased the bone-resorbing activity of osteoclasts and increased the survival of osteoclast precursor cells by decreasing the cellular level of c-Fms and reducing RANK expression. Taken together, these results demonstrate that the VnP-8-DN1 dimer inhibits the early stages of M–CSF– and RANK-induced osteoclast differentiation by binding to c-Fms and inhibiting M-CSF signaling.

Crossing Phylums: Butterfly Wing as a Natural Perfusable Three-Dimensional (3D) Bioconstruct for Bone Tissue Engineering.

Despite the advent of promising technologies in tissue engineering, finding a biomimetic 3D bio-construct capable of enhancing cell attachment, maintenance, and function is still a challenge in producing tailorable scaffolds for bone regeneration. Here, osteostimulatory effects of the butterfly wings as a naturally porous and non-toxic chitinous scaffold on mesenchymal stromal cells are assessed. The topographical characterization of the butterfly wings implied their ability to mimic bone tissue microenvironment, whereas their regenerative potential was validated after a 14-day cell culture. In vivo analysis showed that the scaffold induced no major inflammatory response in Wistar rats. Topographical features of the bioconstruct upregulated the osteogenic genes, including COL1A1, ALP, BGLAP, SPP1, SP7, and AML3 in differentiated cells compared to the cells cultured in the culture plate. However, butterfly wings were shown to provide a biomimetic microstructure and proper bone regenerative capacity through a unique combination of various structural and material properties. Therefore, this novel platform can be confidently recommended for bone tissue engineering applications.

Validation and scalability of homemade polycaprolactone macrobeads grafted with thermo-responsive poly(N-isopropylacrylamide) for mesenchymal stem cell expansion and harvesting.

In this study, polycaprolactone (PCL) macrobeads were prepared by an oil‐in‐water (o/w) emulsion solvent evaporation method with poly(vinyl alcohol) (PVA) as an emulsifier and conjugated to poly(N‐isopropylacrylamide) (PNIPAAm) to be used as cell carriers with noninvasive cell detachment properties (thermo‐response). Following previous studies with PCL‐PNIPAAm carriers, our objectives were to confirm the successful conjugation on homemade macrobeads and to show the advantages of homemade production over commercial beads to control morphological, biological, and fluidization properties. The effects of PCL concentration on the droplet formation and of flow rate and PVA concentration on the size of the beads were demonstrated. The size of the beads, all spherical, ranged from 0.5 to 3.7 mm with four bead categories based on production parameters. The morphology and size of the beads were observed by scanning electron microscopy to show surface roughness enhancing cell attachment and proliferation compared to commercial beads. The functionalization steps with PNIPAAm were then characterized and confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersion spectroscopy. PNIPAAm‐grafted macrobeads allowed mesenchymal stem cells (MSCs) to spread and grow for up to 21 days. By reducing the temperature to 25°C, the MSCs were successfully detached from the PCL‐PNIPAAm beads as observed with fluorescence microscopy. Furthermore, we validated the scalability potential of both macrobeads production and conjugation with PCL, to produce easily kilograms of thermo‐responsive macrocarriers in a lab environment. This could help moving such approaches towards clinically and industrially relevant processes were cell expansion is needed at very large scale.

Hybrid electrospun scaffolds based on polylactic acid/ PAMAM dendrimer/gemini surfactant for enhancement of synergistic antibacterial ability for biomedical application

Hybrid electrospun scaffolds based on poly (L-lactic acid) (PLLA)/poly (amidoamine) (PAMAM-G2) dendrimer/gemini surfactant were fabricated for the enhancement of synergistic antibacterial activities. The second generation of poly (amidoamine) (PAMAM-G2) and cationic gemini surfactant were utilized to functionalize the optimum electrospun scaffolds. The gelatination process was utilized to improve the wettability of PLLA scaffolds to extend cell attachment and cell proliferation. PLLA nanofibrous scaffolds were characterized by energy dispersion x-ray, scanning electron microscopy images, mechanical properties, water contact angle, Fourier transform infrared spectroscopy, zeta potential and antibacterial assessment. In vitro cell biocompatibility was evaluated by 3-(4, 5- dimethylthiazoyl-2-yl)-2, 5-diphenyltetrazolium bromide assay and morphology of PC-12 cells cultured on hybrid nanofibrous scaffolds and gelatinized ones. The results indicated that the optimum scaffolds could successfully modify the characteristics of PLLA scaffolds leading to much more appropriate physical and chemical properties. In addition, gelatinized nanofibrous scaffolds reveal more wettability enhancing cell attachment and proliferation. Furthermore, using poly (amidoamine) (PAMAM-G2) and gemini surfactant reveals synergetic antibacterial activity due to the competition between both cationic groups of PAMAM and gemini surfactant. Finally, improved cell adhesion and cell viability on modified scaffolds were confirmed. These favorable properties give a chance for these scaffolds to be used in a wide variety of biomedical applications.