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We have designed a unique injectable bioactive hydrogel comprising of alginate, gelatin, and nanocrystalline hydroxyapatite and loaded with osteoblasts, with the ability to infiltrate into three-dimensional Ti-6Al-4V scaffolds with interconnected porous architecture, fabricated by electron beam melting. A two-step crosslinking process using the EDC/NHS and CaCl 2 was adopted and found to be effective in the fabrication of cell-loaded hydrogel/Ti-6Al-4V scaffold system. This hybrid Ti-6Al-4V scaffold/hydrogel system was designed for the reconstruction of bone defects, which are difficult to heal in the absence of suitable support materials. The hybrid Ti-6Al-4V/hydrogel system favourably modulated the biological functions, namely, adhesion, proliferation, cell-to-cell, and cell-material communication because of the presence of extracellular matrix-like hydrogel in the interconnected porous structure of 3D printed Ti-6Al-4V scaffold. The hydrogel was cytocompatible, which was proven through live/dead assay, the expression level of prominent proteins for cell adhesion and cytoskeleton, including 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay. Furthermore, the high bone formation ability of the hydrogel was confirmed using alkaline phosphatase assay. A high equilibrium water content (~97%) in the hydrogel enables the delivery of cells and bioactive molecules, necessary for bone tissue growth. Although not studied, the presence of hydrogel in the pores of the scaffold can provide the space for the cell migration as well as vascularization through it, required for the effective exchange of nutrients. In conclusion, we underscore that the 3D-printed Ti-6Al-4V scaffold-loaded with bioactive hydrogel to treat the bone defects significantly impacted cellular functions and cell-material interaction., (Copyright © 2017 John Wiley & Sons, Ltd.)

Titanium alloys (Ti-6Al-4V and Ti-6Al-7Nb) are widely used for implants, which are characterized by high elastic modulus (∼110 GPa) with (α + β) structure and that may induce undesirable stress shielding effect and immune responses associated with the presence of toxic elements. In this regard, we have combined the attributes of a new alloy design and the concept of additive manufacturing to fabricate 3D scaffolds with an interconnected porous structure. The new alloy is a β-type Ti-24Nb-4Zr-8Sn (Ti2448) alloy with significantly reduced modulus. In the present study, we explore the biological response of electron beam melted low modulus Ti2448 alloy porous mesh structure through the elucidation of bioactivity and osteoblast functions. The cellular activity was explored in terms of cell-to-cell communication involving proliferation, spreading, synthesis of extracellular and intracellular proteins, differentiation, and mineralization. The formation of fine apatite-like crystals on the surface during immersion test in simulated body fluid confirmed the bioactivity of the scaffold surface, which provided the favorable osteogenic microenvironment for cell-material interaction. The combination of unique surface chemistry and interconnected porous architecture provided the desired pathway for supply of nutrients and oxygen to cells and a favorable osteogenic micro-environment for incorporation (on-growth and in-growth) of osteoblasts. The proliferation and differentiation of pre-osteoblasts and their ability to form a well mineralized bone-like extracellular matrix (ECM) by secreting bone markers (ALP, calcium, etc.) over the struts of the scaffold point toward the determining role of unique surface chemistry and 3D architecture of the Ti2448 alloy mesh structure in modulating osteoblasts functions. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 859-870, 2017., (© 2016 Wiley Periodicals, Inc.)

Objectives: Low modulus β-titanium alloys with non-toxic alloying elements are envisaged to provide good biocompatibility and alleviate the undesired stress shielding effect. The objective of this study is to fundamentally elucidate the biological response of novel high strength-low elastic modulus Ti2448 alloy through the study of bioactivity and osteoblast cell functions., Methods: Characterization techniques such as SEM, EDX, XRD, and fluorescence microscopy were utilized to analyze the microstructure, morphology, chemical composition, and cell adhesion. The cellular activity was explored in terms of cell-to-cell communication involving proliferation, spreading, synthesis of extracellular and intracellular proteins, differentiation, and mineralization., Results: The formation of fine apatite-like crystals on the surface during immersion test in simulated body fluid confirmed the bioactivity of the surface, which provided the favorable osteogenic microenvironment for cell-material interaction. The proliferation and differentiation of pre-osteoblasts and their ability to form a well mineralized bone-like extracellular matrix (ECM) by secreting bone markers (ALP, calcium, etc.) over the surface point toward the determining role of unique surface chemistry and surface properties of the Ti-24Nb-4Zr-8Sn (Ti2448) alloy in modulating osteoblasts functions., Significance: These results demonstrated that the low modulus (∼49GPa) Ti2448 alloy with non-toxic alloying elements can be used as a potential dental or orthopedic load-bearing implant material., (Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

We elucidate here the osteoblasts functions and cellular activity in 3D printed interconnected porous architecture of functionally gradient Ti-6Al-4V alloy mesh structures in terms of cell proliferation and growth, distribution of cell nuclei, synthesis of proteins (actin, vinculin, and fibronectin), and calcium deposition. Cell culture studies with pre-osteoblasts indicated that the interconnected porous architecture of functionally gradient mesh arrays was conducive to osteoblast functions. However, there were statistically significant differences in the cellular response depending on the pore size in the functionally gradient structure. The interconnected porous architecture contributed to the distribution of cells from the large pore size (G1) to the small pore size (G3), with consequent synthesis of extracellular matrix and calcium precipitation. The gradient mesh structure significantly impacted cell adhesion and influenced the proliferation stage, such that there was high distribution of cells on struts of the gradient mesh structure. Actin and vinculin showed a significant difference in normalized expression level of protein per cell, which was absent in the case of fibronectin. Osteoblasts present on mesh struts formed a confluent sheet, bridging the pores through numerous cytoplasmic extensions. The gradient mesh structure fabricated by electron beam melting was explored to obtain fundamental insights on cellular activity with respect to osteoblast functions., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The 3D printed metallic implants are considered bioinert in nature because of the absence of bioactive molecules. Thus, surface modification of bioinert materials is expected to favorably promote osteoblast functions and differentiation. In this context, the objective of this study is to fundamentally elucidate the effect of cell-derived decellularized extracellular matrix (dECM) ornamented 3D printed Ti-6Al-4V scaffolds on biological functions, involving cell adhesion, proliferation, and synthesis of vinculin and actin proteins. To mimic the natural ECM environment, the mineralized ECM of osteoblasts was deposited on the Ti-6Al-4V porous scaffolds, fabricated by electron beam melting (EBM) method. The process comprised of osteoblast proliferation, differentiation, and freeze-thaw cycles to obtain decellularized extra cellular matrix (dECM), in vitro. The dECM provided a natural environment to restore the natural cell functionality of osteoblasts that were cultured on dECM ornamented Ti-6Al-4V scaffolds. In comparison to the bare Ti-6Al-4V scaffolds, a higher cell functionality such as cell adhesion, proliferation, and growth including cell-cell and cell-material interaction were observed on dECM ornamented Ti-6Al-4V scaffolds, which were characterized by using markers for focal adhesion and cytoskeleton such as vinculin and actin. Moreover, electron microscopy also indicated higher cell-material interaction and enhanced proliferation of cells on dECM ornamented Ti-6Al-4V scaffolds, supported by MTT assay. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2751-2763, 2016., (© 2016 Wiley Periodicals, Inc.)

The objective of the study is to fundamentally elucidate the biological response of 3D printed mesh structures subjected to plasma electrolytic oxidation process through the study of osteoblast functions. The cellular activity of plasma electrolytic-oxidized mesh structure was explored in terms of cell-to-cell communication involving proliferation, synthesis of extracellular and intracellular proteins, and mineralization. Upon plasma electrolytic oxidation of the mesh structure, a thin layer of bioactive titania with pore size 1-3 µm was nucleated on the surface. The combination of microporous bioactive titania and interconnected porous architecture provided the desired pathway for supply of nutrients and oxygen to cells and tissue and a favorable osteogenic microenvironment for tissue on-growth and in-growth, in relation to the unmodified mesh structure. The formation of a confluent layer as envisaged via electron microscopy and quantitative assessment of the expression level of proteins (actin, vinculin, and fibronectin) point toward the determining role of surface-modified mesh structure in modulating osteoblasts functions. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2488-2501, 2016., (© 2016 Wiley Periodicals, Inc.)

We elucidate here the mechanistic contribution of a novel electroconductive hydroxyapatite-20 wt.% titanium disilicide (HA-TiSi2) composite system in favorably modulating osteoblast functions in relation to the monolithic HA. The higher electrical conductivity of HA-TiSi2(σDC ∼ 67.117 ± 3.57 S/m) in comparison to glass sample effectively guided the electroactive myoblast, leading to their significant alignment and proliferation. This favorable behavior is attributed to the formation of small electrochemical cells between HA and TiSi2phase, which produce a small electric field, directing the electroactive myoblast to migrate and grow in a particular direction. In contrast, no impact of TiSi2on osteoblast function was observed because of their inability to respond to small electric field. However, thein vitrobioactivity in simulated body fluid indicated the nucleation and growth of apatite crystals. Moreover, in the context of load-bearing capability, the presence of 20 wt.% TiSi2in HA led to increase in the fracture toughness by ∼100%. This study underscores the effectiveness of HA-TiSi2in favorably modulating the cellular activity, myoblast in particular., (© The Author(s) 2016.)

We describe here the combined efforts of engineering and biological sciences as a systemic approach to fundamentally elucidate osteoblast functions in functionally graded Ti-6Al-4 V mesh structures in relation to uniform/monolithic mesh arrays. First, the interconnecting porous architecture of functionally graded mesh arrays was conducive to cellular functions including attachment, proliferation, and mineralization. The underlying reason is that the graded fabricated structure with cells seeded from the large pore size side provided a channel for efficient transfer of nutrients to other end of the structure (small pore size), leading to the generation of mineralized extracellular matrix by differentiating pre-osteoblasts. Second, a comparative and parametric study indicated that gradient mesh structure had a pronounced effect on cell adhesion and mineralization, and strongly influenced the proliferation phase. High intensity and near-uniform distribution of proteins (actin and vinculin) on struts of the gradient mesh structure (cells seeded from large pore side) implied signal transduction during cell adhesion and was responsible for superior cellular activity, in comparison to the uniform mesh structure and non-porous titanium alloy. Cells adhered to the mesh struts by forming a sheet, bridging the pores through numerous cytoplasmic extensions, in the case of porous mesh structures. Intercellular interaction in porous structures provided a pathway for cells to communicate and mature to a differentiated phenotype. Furthermore, the capability of cells to migrate through the interconnecting porous architecture on mesh structures led to colonization of the entire structure. Cells were embedded layer-by-layer in the extracellular matrix as the matrix mineralized. The outcomes of the study are expected to address challenges associated with the treatment of segmental bone defects and bone-remodeling through favorable modulation of cellular response. Moreover, the study provides a foundation for a new branch of functionally graded materials with interconnected porous architecture., (© The Author(s) 2015.)

Three-dimensional cellular scaffolds are receiving significant attention in bone tissue engineering to treat segmental bone defects. However, there are indications of lack of significant osteoinductive ability of three-dimensional cellular scaffolds. In this regard, the objective of the study is to elucidate the interplay between bone morphogenetic protein (BMP-2) and osteoblast functions on 3D mesh structures with different porosities and pore size that were fabricated by electron beam melting. Self-assembled dendritic microstructure with interconnected cellular-type morphology of BMP-2 on 3D scaffolds stimulated osteoblast functions including adhesion, proliferation, and mineralization, with prominent effect on 2-mm mesh. Furthermore, immunofluorescence studies demonstrated higher density and viability of osteoblasts on lower porosity mesh structure (2 mm) as compared to 3- and 4-mm mesh structures. Enhanced filopodia cellular extensions with extensive cell spreading was observed on BMP-2 treated mesh structures, a behavior that is attributed to the unique self-assembled structure of BMP-2 that effectively communicates with the cells. The study underscores the potential of BMP-2 in imparting osteoinductive capability to the 3D printed scaffolds., (© 2015 Wiley Periodicals, Inc.)

The endogenous electric field plays an important role in accomplishing various functions including communication with the brain and with different parts of the physiological system, wound healing, and cellular functions. Furthermore, the endogenous electric field can be modified using the external electric field to induce changes in cell functionality. Given that the cells grow in contact with the dynamic flow of blood and nutrients, the objective of the study is to elucidate the effect of media flow (dynamic conditions) on osteoblast functions at a pulsed DC (direct current) electric field of strength of 0.5-1 V cm(-1) and compared with the static conditions (no flow of media and in the presence of an electric field). The electric field provided a guiding cue to cells to move towards the cathode. An interesting aspect of the electric field was the migration of cells towards the cathode with the axis parallel to the direction of the electric field such that the lamellipodia was aligned. Furthermore, there was an absence of membrane blebbing or necrosis at the cathode. However, cell growth and expression of proteins (actin and vinculin) were higher than the anode. In contrast, at the anode, while the cells were healthy, the cell growth was less such that the expression of vinculin was relatively low together with less densely packed actin stress fibers. It is underscored that the biological functionality is favorably altered in the presence of an electrical field under dynamic conditions with a consequent effect on cell proliferation, growth, and expression level of prominent proteins, actin and vinculin.

The successful integration of a biomedical device is governed by the surface properties of the material and also depends on the interaction with the physiological fluid involving adsorption of proteins on the surface. Pre-adsorbed proteins act as pilots for cell adhesion and subsequently govern cellular activity. In this regard, nanograined materials are excellent vehicles to obtain an unambiguous understanding of protein adsorption, which regulate cell adhesion and cellular activity. Toward this end, we have used the concept of phase reversion-induced nanograined structure to understand grain structure-induced self-assembly of a model protein, bovine serum albumin. Furthermore, in the context of bio-mechanical interlocking between implant and bone, and osseointegration of the implant, grain boundaries were electrochemically grooved and studied for osteoblast functions. Experiments indicated that the significant differences in cell attachment, proliferation, and expression level of prominent proteins (actin, vinculin, and fibronectin) is related to synergistic effects of grain structure, pre-adsorbed protein, and grooving of grain boundaries such that the osteoblasts functions and cellular activity is promoted on the nanostructured surface in relation to the coarse-grained counterpart.

Protein adsorption is one of the first-few events that occur when a biomedical device comes in contact with the physiological system. The adsorption process is subsequently followed by communication with cells and formation of tissue. Given the strong interest in nanostructured surfaces, we describe here the impact of grain structure from nanograined (NG) regime to coarse-grained (CG) regime on the self-assembly of proteins (bovine serum albumin) and consequent functional response of osteoblasts. The objective is accomplished using the innovative concept of "phase reversion" that enables a wide range of grain size (from NG to CG regime) to be obtained using an identical set of parameters, besides additional attributes of high strength/weight ratio and wear resistance. Depending on the grain structure a consistent and significant change in the adsorption characteristics of protein was observed at biointerface, such that the cell density was statistically different. The high surface coverage and leaf-like conformation of adsorbed protein on NG surface as compared to bare branch-like structure with low surface coverage on the CG surface, was beneficial in favorably modulating cellular activity (osteoblast functions: cell attachment, proliferation, actin, vinculin, and fibronectin expression). This is the first report that elucidates the impact of grain structure from NG to CG regime on cellular activity., (Copyright © 2013 Wiley Periodicals, Inc.)

There are serious concerns on the toxicity of vanadium in Ti-6Al-4V alloy. In this regard, we describe the biological footprint of Ti-6Al-4V and compare with a viable alternate Ti-6Al-7Nb alloy, in terms of novel experimentation pertaining to cellular activity that include qualitative and quantitative analysis of Feret's diameter of cells, area, and perimeter, and proteins-actin, vinculin, and fibronectin. Interestingly, Ti-6Al-7Nb was characterized by superior cell attachment, proliferation, viability, morphology, and spread, which were significantly different from Ti-6Al-4V alloy. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions in Ti-6Al-7Nb alloy. These striking observations suggest enhanced cell-substrate interaction and activity on the surface of niobium-containing titanium alloy. The significant differences in the cellular response between the two alloys clearly point to the determining role of alloying element (Nb versus V) in a conclusive manner. Based on this study, next generation of titanium alloys is proposed to focus on niobium-containing alloy., (Copyright © 2013 Wiley Periodicals, Inc.)

The rapid adsorption of proteins occurs during the early stages of biomedical device implantation into physiological systems. In this regard, the adsorption of proteins is a strong function of the nature of a biomedical device, which ultimately governs the biological functions. The objective of this study was to elucidate the interplay between nanostructured carbon-modified (graphene oxide and single-walled carbon nanohorn) chitosan scaffolds and consequent protein adsorption and biological function (osteoblast function). We compare and contrast the footprint of protein adsorption on unmodified chitosan and nanostructured carbon-modified chitosan. A comparative analysis of cell-substrate interactions using an osteoblast cell line (MC3T3-E1) implied that biological functions were significantly enhanced in the presence of nanostructured carbon, compared with unmodified chitosan. The difference in their respective behaviors is related to the degree and topography of protein adsorption on the scaffolds. Furthermore, there was a synergistic effect of nanostructured carbon and protein adsorption in terms of favorably modulating biological functions, including cell attachment, proliferation and viability, with the effect being greater on nanostructured carbon-modified scaffolds. The study also underscores that protein adsorption is favored in nanostructured carbon-modified scaffolds such that bioactivity and biological function are promoted., (Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Metallic biomedical devices with nanometer-sized grains (NGs) provide surfaces that are different from their coarse-grained (CG) (tens of micrometer) counterparts in terms of increased fraction of grain boundaries (NG>50%; CG<2-3%). The novel concept of 'phase-reversion' involving a controlled deformation-annealing sequence is used to obtain a wide range of grain structures, starting from the NG regime to the CG regime, to demonstrate that the grain structure significantly impacts cellular interactions and osteoblast functions. The uniqueness of this concept is the ability to address the critical aspect of cellular activity in nanostructured materials, because a range of grain sizes from NG to CG are obtained in a single material using an identical set of parameters. This is in addition to a high strength/weight ratio and superior wear and corrosion resistance. These multiple attributes are important for the long-term stability of biomedical devices. Experiments on the interplay between grain structure from the NG regime to CG in austenitic stainless steel on osteoblast functions indicated that cell attachment, proliferation, viability, morphology and spread varied with grain size and were favorably modulated on the NG and ultrafine-grain structure. Furthermore, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on the NG surface. The differences in the cellular response with change in grain structure are attributed to grain structure and degree of hydrophilicity. The study lays the foundation for a new branch of nanostructured materials for biomedical applications., (Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Bioactivity is an important aspect that can be appropriately used to tune the cellular interactions occurring at the biomaterial-physiological interface. In this regard, we explore here the nano- or quantum-size effects of a highly dispersible nanostructured carbon present in the void space between the polymers chains (Nylon 6,6) in modulating the cellular functions when osteoblasts are seeded on biocompatible substrates. The filling-up of void space in polymer facilitates filopodia to access the extracellular matrix, enabling integrin receptors to bind to the artificial biomedical device, promoting cellular interactions. In this regard, the fundamental principles of materials processing and cellular biology were combined to elucidate the mechanism of cell-substrate interactions and the molecular machinery controlling the cell response. This is accomplished by investigating cell attachment, proliferation, and morphology, including cytomorphometry evaluation and quantitative assessment of prominent proteins, actin, vinculin, and fibronectin that are sensitive to cell-substrate interactions., (Copyright © 2012 Wiley Periodicals, Inc.)

The rapid adsorption of proteins is the starting and primary biological response that occurs when a biomedical device is implanted in the physiological system. The biological response, however, depends on the surface characteristics of the device. Considering the significant interest in nano-/ultrafine surfaces and nanostructured coatings, we describe here, the interplay between grain structure and protein adsorption (bovine serum albumin: BSA) on osteoblasts functions by comparing nanograined/ultrafine-grained (NG/UFG) and coarse-grained (CG: grain size in the micrometer range) substrates by investigating cell-substrate interactions. The protein adsorption on NG/UFG surface was beneficial in favorably modulating biological functions including cell attachment, proliferation, and viability, whereas the effect was less pronounced on protein adsorbed CG surface. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on protein adsorbed NG/UFG surface. The functional response followed the sequence: NG/UFG(BSA) > NG/UFG > CG(BSA) > CG. The differences in the cellular response on bare and protein adsorbed NG/UFG and CG surfaces are attributed to cumulative contribution of grain structure and degree of hydrophilicity. The study underscores the potential advantages of protein adsorption on artificial biomedical devices to enhance the bioactivity and regulate biological functions., (Copyright © 2012 Wiley Periodicals, Inc.)

We elucidate here for the first time the structure-processing-functional property relationship in chitosan (CS)-based scaffolds, where molecular machinery governing proliferation and growth of osteoblasts is mediated by nanostructured carbon. The interconnected network structure of organic-inorganic scaffolds was obtained by covalent linkage of carboxyl group of functionalized single-walled carbon nanohorn with the amine group of CS. The molecular-scale dispersibility of functionalized nanostructured carbon was an important physicochemical factor influencing cellular interactions and biological response. Furthermore, it was beneficial in promoting the biocompatibility and the degradation product of the scaffolds. The hydrophilicity, good water retention ability, and interconnected porous structure of organic-inorganic scaffolds enabled pronounced cell attachment and proliferation and enhanced the stability toward enzymatic degradation. The infiltration of cells and colonization of the pores of the scaffolds and cellular interactions were promoted due to covalent linkage of nanostructured carbon with CS. Additionally, the interconnectivity of porous scaffolds facilitated cells to infiltrate inside the pores of CS-nanostructured scaffolds, implying that nanostructured carbon merits consideration in tissue engineering., (Copyright © 2012 Wiley Periodicals, Inc.)

The objective of the study is to elucidate the interplay between fibronectin-metal hybrid surfaces and osteoblast function. The practical relevance is that a significant initial step in the process of prosthetic integration within a physiological system is the rapid adsorption of proteins, including fibronectin, on the surface of biomedical device. Here, we compare and contrast the cell-substrate interactions on bare and protein-modified surfaces. The protein adsorption on the surface was beneficial in favorably modulating biological functions including cell attachment, proliferation, and viability. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on protein-adsorbed surfaces. These results support the hypothesis that protein adsorption on artificial biomedical devices can promote bioactivity and regulate biological functions., (Copyright © 2012 Wiley Periodicals, Inc.)

We here describe the structure-process-property relationship of graphene oxide-mediated proliferation and growth of osteoblasts in conjunction with the physico-chemical, mechanical, and structural properties. Chitosan-graphene network structure scaffolds were synthesized by covalent linkage of the carboxyl groups of graphene oxide with the amine groups of chitosan. The negatively charged graphene oxide in chitosan scaffolds was an important physico-chemical factor influencing cell-scaffold interactions. Furthermore, it was advantageous in enhancing the biocompatibility of the scaffolds and the degradation products of the scaffolds. The high water retention ability, hydrophilic nature, and high degree of interconnectivity of the porous structure of chitosan-graphene oxide scaffolds facilitated cell attachment and proliferation and improved the stability against enzymatic degradation. The cells infiltrated and colonized the pores of the scaffolds and established cell-cell interactions. The interconnectivity of the porous structure of the scaffolds helps the flow of medium throughout the scaffold for even cell adhesion. Moreover, the seeded cells were able to infiltrate inside the pores of chitosan-graphene oxide scaffolds, suggesting that the incorporation of polar graphene oxide in scaffolds is promising for bone tissue engineering., (Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Metallic materials with submicron- to nanometer-sized grains provide surfaces that are different from conventional polycrystalline materials because of the large proportion of grain boundaries with high free energy. In the study described here, the combination of cellular and molecular biology, materials science and engineering advances our understanding of cell-substrate interactions, especially the cellular activity between preosteoblasts and nanostructured metallic surfaces. Experiments on the effect of nano-/ultrafine grains have shown that cell attachment, proliferation, viability, morphology and spread are favorably modulated and significantly different from conventional coarse-grained structures. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on nanograined/ultrafine-grained substrate. These observations suggest enhanced cell-substrate interaction and activity. The differences in the cellular response on nanograined/ultrafine-grained and coarse-grained substrates are attributed to grain size and degree of hydrophilicity. The outcomes of the study are expected to reduce challenges to engineer bulk nanostructured materials with specific physical and surface properties for medical devices with improved cellular attachment and response. The data lay the foundation for a new branch of nanostructured materials for biomedical applications.

A covalently cross-linked injectable hybrid hydrogel, namely, alginate/poly(amidoamine) (PAMAM), with the objective of cell delivery was innovatively designed and synthesized using tetra-amino-functional PAMAM dendrimer as the cross-linker. With the increase in percentage of PAMAM cross-linker, the pore size and swelling ratio of hydrogels were in the range of 57 ± 18 μm to 88 ± 25 μm and 110 ± 16 to 157 ± 20, respectively. The study of attachment and proliferation of MC3T3-E1 pre-osteoblasts using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay through indirect and direct contact methods indicated a continuous increase in metabolically active live cells with time, implying non-cytotoxicity of the synthesized hydrogel. The live–dead assay showed >95% of live cells for alginate/PAMAM hydrogels, suggesting viability of the encapsulated cells. When the percentage of PAMAM cross-linker in alginate/PAMAM hydrogel was increased from 5 to 25, the percentage degradation rate decreased from 1.1 to 0.29%/day. Given that the poly(ethylene glycol) is commonly used cross-linker for hydrogel syntheses, we compared the behavior with poly(ethylene glycol). The incorporation of poly(ethylene glycol) in alginate/PAMAM hydrogel reduced the activity of MC3T3-E1 cells and their viability compared to the alginate/PAMAM hydrogels. The protonation of amino groups in alginate/PAMAM injectables under physiological conditions led to the formation of cationic hydrogels. These cationic hydrogels showed enhanced cell encapsulation and attachment ability because of electrostatic interaction with negatively charged cell surface as determined by cell adhesion and extensions from scanning electron microscope and vinculin assay and ability of in situ calcium phosphate mineralization. These observations point toward the potential use as an injectable scaffold for cell delivery and tissue engineering applications. [ABSTRACT FROM AUTHOR]

The successful integration of a biomedical device is governed by the surface properties of the material and also depends on the interaction with the physiological fluid. In this regard, bulk nanostructured materials are recently being recognised as potential implant materials alternative to conventional materials. The potential application of such next generation materials as biomedical implants has recently been evaluated by investigating the effect of wide range of grain sizes on multiple cell activities. In this review, recent advances in biomedical applications of bulk nanostructured materials are highlighted with special focus on the effect of phase reversion-induced nanograined size on protein adsorption and cell–material interactions. Furthermore, the effect of grain structure on antimicrobial effect is also discussed. Osteoblasts functions and cellular activity are promoted on the nanostructured surface in relation to the coarse-grained counterpart. Finally, the advantages of phase reversion approach to produce multifunctional bio-implant materials are addressed. [ABSTRACT FROM PUBLISHER]

Metallic implant materials used in load-bearing applications are inert in nature in their native state. The surface properties of the material and its interaction with the surrounding physiological fluid determine the success of the biomedical implant. In this regard, bioactive nanostructured coatings are being recognised as potential approach to enhance the biological and corrosion properties of the conventional inert materials. In this review, recent advances in biomedical applications of nanostructured hydroxyapatite coatings on stainless steel implant materials are highlighted with special focus on the electrochemical deposition of hydroxyapatite and their consequent biological activity. Furthermore, osteoblasts functions and cellular activity on the nanostructured hydroxyapatite coatings processed by other techniques is also discussed. The potential application of such next generation materials as biomedical implants is also addressed. [ABSTRACT FROM PUBLISHER]

The endogenous electric field plays a determining role in impacting biological functions including communication with the physiological system, brain, and bone regeneration by influencing cellular functions. From this perspective, the objective of the study described here is to elucidate the effect of external electric field under dynamic conditions, in providing a guiding cue to osteoblasts in terms of cell–cell interactions and synthesis of prominent adhesion and cytoskeleton proteins. This was accomplished using pulsed direct current electric field of strength 0.1–1 V/cm. The electric field provided guided cue to the cells to migrate toward cathode. Membrane blebbing or necrosis was nearly absent in the vicinity of cathode at 0.1 and 0.5 V/cm electric field strength. Moreover, a higher cell proliferation as well as higher expression of vinculin and densely packed actin stress fibers was observed. At anode, the cells though healthy but expression of actin and vinculin was less. We underscore for the first time that the biological functionality can be favorably modulated on 3D printed scaffolds in the presence of electric field and under dynamic conditions with consequent positive effect on cell proliferation, growth, and expression level of prominent proteins. [ABSTRACT FROM AUTHOR]

The study concerns processing-structure-functional property relationship in organic-inorganic hybrid scaffolds based on grafted collagen for bone tissue engineering. Biodegradable polyester, polycaprolactone (PCL) and nanohydroxyapatite were used to fabricate three-dimensional porous scaffolds by adopting a combination of solvent casting, particulate leaching, and polymer leaching approaches. The PCL scaffold was subsequently surface modified by chemical bonding of 1,6-hexanediamine to the ester groups of PCL to introduce free NH2 groups. The introduction of NH2 groups as active sites enabled immobilization of biocompatible macromolecule, collagen, on the aminolyzed PCL via a cross-linking agent, glutaraldehyde. The osteoblasts' functions, notably cell adhesion, proliferation, and mineralization, were favorably modulated because of the chemical interaction between Arg-Gly-Asp domains in collagen molecule and integrin receptor in the cell membrane. The study underscores the significance of grafting collagen on PCL-nHA scaffold in modulating cellular activity and biological functions expanding its current use in soft tissue engineering to hard tissue regeneration. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2919-2931, 2015. [ABSTRACT FROM AUTHOR]

There is currently a strong interest in nano- and ultrafine grained planar surface and coatings in the biomedical community, but there is a lack of understanding with regard to the interplay between grain size and cell differentiation. Motivated by our previous studies on the interplay between grain structure and biological response, we describe here the influence of grain size from nano- to coarse grain on osteoblast differentiation and mineralisation. This aspect constitutes the objective of the study. Experiments on the interplay between grain structure and osteoblast functions indicated that cell differentiation and mineralisation varied with grain size and were favourably modulated on the nanograin (NG) and ultrafine grain (UFG) surface, consistent with alkaline phosphatase activity. Furthermore, it is elucidated that the grain structure strongly influences the ability of the surface to form a well mineralised bone-like extracellular matrix by secreting bone markers, which in turn is governed by grain structure-hydrophilicity relationship. The study demonstrates potential for a new branch of nanostructured materials for biomedical applications. [ABSTRACT FROM AUTHOR]

Nylon 6,6 is used for biological applications including gastrointestinal segments, tracheal tubes and sutures, vascular graft, and for hard tissue reconstruction. While it is a relatively inexpensive polymer, it is not widely acceptable as a preferred biomaterial because of bioactivity. To this end, we have discovered the exciting evidence that introduction of a novel nanostructured carbon, graphene, in the void space between the nylon chains and processing at elevated pressure favorably stimulates cellular functions and provides high degree of cytocompatibility. The cell-substrate interactions on stand alone Nylon 6,6 and Nylon 6,6-graphene oxide hybrid system were investigated in terms of cell attachment, viability, proliferation, and assessment of proteins, actin, vinculin, and fibronectin. The enhanced biological functions in the nanostructured hybrid system are attributed to relatively superior hydrophilicity of the surface and to the presence of graphene. Furthermore, it is proposed that the negatively charged graphene interacts with the polar nature of cells and the culture medium, such that the interaction is promoted through polar forces. This is accomplished by investigating cell attachment, proliferation, and morphology, including cytomorphometry evaluation, and quantitative assessment of prominent proteins, actin, vinculin, and fibronectin that are sensitive to cell-substrate interactions. Osteoblasts were studied to establish the practical viability of the hybrid nanostructured biomaterial. The study strengthens the foundation for utilizing nano- or quantum-size effects of nanostructured biomaterials. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013. [ABSTRACT FROM AUTHOR]