Tissue Engineering Research Articles

PLA/PCL POLYMER NANOCOMPOSITE WITH SILVER AND COPPER NANOPARTICLES AND LAVENDER ESSENTIAL OIL: SYNTHESIS, CHARACTERIZATION AND APPLICATION IN TISSUE ENGINEERING

The present work aims to synthesize, characterize, and evaluate the cytotoxicity and antimicrobial activity of PLA/PCL polymeric nanocomposite with silver nanoparticles (AgNPs) and copper (CuNPs) and the addition of lavender essential oil (LEO) for application in tissue engineering. For the synthesis of the nanocomposite films, the central composite rotational design (CCRD 2²) was used, where the ideal condition was 0.5%wt. of AgNPs and CuNPs (3:1D) with a higher cell viability (196.1%) after 24 hours. After defining the ideal condition, the effect of incorporating LEO into the polymer blend and nanoparticles in the proportions of 0.5 (3:1D0.5), 0.75 (3:1D0.75) and 1 v v-1 (3:1D1) was evaluated. All nanocomposite films were characterized structurally, morphologically, thermally, and mechanically by X-ray diffraction (XRD), Field Emission Gun–Scanning Electron Microscopy (FEG-SEM), Thermogravimetric analysis (TGA), contact angle and mechanical Properties (displacement and maximum tension). To evaluate cytotoxicity, an in vitro safety profile was performed in HFF-1 (fibroblasts) and HaCat (keratinocytes) cell lines, where PLA/PCL polymer blend with 0.5 %wt. of AgNPs and CuNPs (3:1D) and PLA/PCL polymer blend with 0.5 %wt. of AgNPs and CuNPs and LEO (0.5 v v-1) (3:1D0.5) nanocomposite film showed the best cell viability without the nitric oxide (NO) generation, total levels of reactive oxygen species (ROS) or dsDNA release for the HFF-1 and HaCat cell lines, as well as genoprotective characteristic and without genotoxic profile. Moreover, the tests were carried out on the pH of injured skin at different immersion times (3, 6, 12 and 24 hours) and didn´t show cell death or inflammatory reaction. For the antimicrobial activity, the 3:1D, 3:1D0.5, and PLA/PCL polymer blend with 0.5 %wt. of AgNPs and CuNPs and LEO (0.75 v v-1) (3:1D0.75) nanocomposite films showed the formation of biofilm for S. aureus, E. coli, P. aeruginosa and K. pneumoniae. Therefore, the PLA/PCL polymer nanocomposite with AgNPs and CuNPs showed potential application as a healing dressing for skin regeneration.

Marine Polysaccharides for Gene Delivery: Approaches and Prospective

: Polysaccharides from marine sources have been increasingly used in recent research due to their availability, affordability, biocompatibility, and biodegradability. These features make them promising candidates for use in nanotechnology in a wide variety of drug delivery systems, including those for gene therapy, tissue engineering, cancer therapy, wound dressing, biosensors, and water purification. Marine polysaccharides are of particular interest due to their distinct physicochemical and biological properties like chitin, alginate, carrageenan, fucoidan, and chitosan has inspired an array of nanostructures. This article summarizes the history, chemical composition, biological functions, and nanomedical uses of these marine polysaccharides. Marine polysaccharides are the topic of this review due to their potential utility in gene transfer.

Simultaneous processing of both handheld biomixing and biowriting of kombucha cultured pre-crosslinked nanocellulose bioink for regeneration of irregular and multi-layered tissue defects

The nanocellulosic pellicle derived from the symbiotic culture of bacteria and yeast (Kombucha SCOBY) is an important biomaterial for 3D bioprinting in tissue engineering. However, this nanocellulosic hydrogel has a highly entangled gel network. This needs to be partially modified to improve its processability and extrusion ability for its applications in the 3D bioprinting area. To control its mechanical and biological properties for direct 3D bioprinting applications, uniform reinforcement of nanocellulose-interacting polymers and nanoparticles in such a prefabricated gel network is essential. In this study, the hydrogel network is partially hydrolyzed with organic acid and subsequently transformed into a 3D bioprintable polyelectrolyte complex with chitosan and kaolin nanoparticles without any chemical crosslinker using a handheld 3D bioprinter. This handheld bioprinter ensures homogeneity in both biomixing and bioprinting of chitosan and kaolin within the modified nanocellulose network for multi-layered bioprinted scaffolds through an extensional shear mechanism. The biomixing simulation, mechanical (static, dynamic, and cyclic), 3D bioprinting, and cellular studies confirm the homogeneous biomixing of kaolin nanoparticles and live cells in this nanocellulose-chitosan polyelectrolyte hydrogel. The combination of SCOBY-derived nanocellulose-chitosan bioink with kaolin nanoparticles and a screw-driven handheld extrusion bioprinter demonstrates a promising platform for layer-by-layer regeneration of complex tissues with homogeneous cell/particle distribution with high cell viability.

The role of histology in tissue engineering: Significance of complex morphological characterization of decellularized foreskin scaffolds

The role of histology in tissue engineering: Significance of complex morphological characterization of decellularized foreskin scaffolds

Sr-Mg co-doped Hardystonite/Polycaprolactone electrospun scaffolds: Fabrication and Characterization for enhanced bone regeneration

The production of scaffolds is a primary objective in tissue engineering for treating bone defects and diseases. The electrospinning process offers a promising technique to create structures resembling the extracellular matrix. Artificial polymeric grafts, such as poly(caprolactone) (PCL), often face issues of low strength and degradation. To overcome these limitations, we introduce ceramic reinforcing particles, specifically hardystonite (Ca2ZnSi2O7), known for its benefits in tissue regeneration. Considering the undeniable role of strontium and magnesium in bone regeneration, the aim of this study was to investigate and compare produced scaffolds with and without dopant elements, incorporated into hardystonite. Initially, strontium-magnesium-doped hardystonite (DHT) nanopowder was synthesized through mechanical milling followed by thermal treatment. The successful formation of a single-phase hardystonite structure was verified by X-ray diffraction (XRD), with estimated crystallite and particle sizes of approximately 41.6nm and 77.23 ± 36.60 nm, respectively. Subsequently, PCL/DHT composite scaffolds were fabricated with 3 wt%, 5 wt%, and 10 wt% bioceramic content. These scaffolds were assessed for fiber morphology, physical and chemical properties, hydrophilicity, surface roughness, mechanical characteristics, degradation, and biocompatibility. The results indicate that PCL/5 wt% DHT scaffolds exhibit superior biological, physical, and mechanical properties. Across all these tests, the PCL/5 wt% DHT scaffold consistently outperformed the others, suggesting its promising potential in bone tissue engineering.

Recent Advancements in Applications of Alginates in Drug Delivery, Tissue Engineering, and Biomedical Field

Abstract: Alginates, originating from the cell walls of brown algae, constitute a class of biopolymers known for their linear, unbranched architecture. Comprising both homopolymeric and heteropolymeric blocks, these polymers are constructed through glycosidic bonds linking β-D mannuronic acid and α-L-guluronic acid units in a 1-4 configuration. The specific arrangement of these monomers, whether in alternate, sequential, or random configurations, imparts distinct physical and chemical properties to the polysaccharide. The composition and organization of alginates play a pivotal role in dictating their performance and potential applications, particularly within the realm of biomedicine. A comprehensive understanding of their intricate chemistry and characterization is imperative for effective utilization. This knowledge serves as the cornerstone for designing tailored delivery systems and strategies to leverage the unique attributes of alginates for therapeutic and diagnostic purposes. Commercially, alginates are offered in diverse forms and hues, encompassing sodium, potassium, or ammonium salts. Alginates show commendable biocompatibility and biodegradability and exhibit a marked absence of antigenicity and toxicity. In addition, their ability to form chelates with divalent cations and to facilitate the creation of pH-responsive gels through crosslinking with calcium and magnesium significantly enhances their versatility. Alginates possess a molecular weight range of from 60,000 to 700,000 Da, a parameter capable of adjusting to align with specific applications. This inherent versatility positions them as valuable assets across a spectrum of fields, including pharmaceuticals, tissue regeneration scaffolds, drug delivery systems, and imaging agents. The review article provides a comprehensive exploration of the diverse applications of alginates in tissue engineering, drug delivery, and various domains within biomedicine. By delving into the nuanced characteristics and behaviors of alginates, we aspire to unlock their full potential in advancing therapeutic and diagnostic interventions.

Thermosensitive Hydrogels for Periodontal Regeneration: A Systematic Review of the Evidence.

Thermosensitive hydrogels are now among the most commonly used biomaterials in tissue engineering. Due to their unique characteristics, this review aimed to evaluate the suitability of thermosensitive hydrogels in periodontal regeneration. PubMed, Scopus, and Web of Science databases were searched until March 25, 2024, to retrieve relevant articles. The eligibility criteria for the included studies were determined by the designed PICO elements. Results from each included study were extracted, focusing on the three main areas: thermosensitivity, cellular characteristics, and in vivo characteristics. Nineteen studies were included in our study. The thermosensitivity assessment of the hydrogels indicated a range of sol-gel transition times from 40 s to 20 min based on the type of polymers and the fabrication process. The cellular characterization was assessed based on three main cellular behaviors: cellular viability/proliferation, differentiation, and migration. The in vivo characterization was performed based on two main approaches: radiographic and histologic evaluation. The results indicated that the addition of bioactive agents could enhance the in vivo efficacy of thermosensitive hydrogels in periodontal regeneration through three main areas: antimicrobial, anti-inflammatory, and regenerative effects.

Advancements in textile techniques for cardiovascular tissue replacement and repair.

In cardiovascular therapeutics, procedures such as heart transplants and coronary artery bypass graft are pivotal. However, an acute shortage of organ donors increases waiting times of patients, which is reflected in negative effects on the outcome for the patient. Post-procedural complications such as thrombotic events and atherosclerotic developments may also have grave clinical implications. To address these challenges, tissue engineering is emerging as a solution, using textile technologies to synthesize biomimetic scaffolds resembling natural tissues. This comprehensive analysis explains methodologies including electrospinning, electrostatic flocking, and advanced textile techniques developed from weaving, knitting, and braiding. These techniques are evaluated in the context of fabricating cardiac patches, vascular graft constructs, stent designs, and state-of-the-art wearable sensors. We also closely examine the interaction of distinct process parameters with the biomechanical and morphological attributes of the resultant scaffolds. The research concludes by combining current findings and recommendations for subsequent investigation.

Optimization of chitosan-gelatin-based 3D-printed scaffolds for tissue engineering and drug delivery applications

The combination of biocompatible materials and advanced three-dimensional (3D) additive manufacturing technologies holds great potential in the development of finely tuned complex scaffolds with reproducible macro- and micro-structural characteristics for biomedical applications, such as tissue engineering and drug delivery. In this study, biocompatible printable inks based on chitosan, collagen and gelatin were developed and 3D-printed with a pneumatic-based extrusion printer. The printability of various chitosan–gelatin (CS-Gel) hydrogel inks was assessed by evaluating the quality of the printed constructs. The inks required an extrusion pressure of 150 ± 40 MPa with G22 and G25 nozzles for optimal printing. Inks with low chitosan concentrations (<4% w/v) exhibited poor printability, while inks with 4 % w/v chitosan and 1 % w/v gelatin (CG) demonstrated satisfactory extrusion and printing quality. The addition of collagen (0.1 % w/v) to the optimized ink (CGC) did not compromise printability. Post-printing stabilization using KOH produced self-supporting scaffolds with consistent morphological integrity, while weaker bases like NaOH/EtOH and ammonia vapors resulted in lower pore sizes and reduced structural stability. Water evaporation studies showed that neutralized samples had slower evaporation rates due to the strong intermolecular interactions formed during the neutralization process, contributing to a stable crosslinked network. FTIR spectra confirmed the formation of polyelectrolyte complexes in the CS-Gel and CS-Gel-Collagen blends, further enhancing structural stability. Swelling tests indicated that neutralized constructs maintained stability in different pH environments, with KOH-treated samples exhibiting the lowest swelling ratios and the highest structural stability. After optimizing the ink composition, 10 wt% Levofloxacin was loaded in the constructs as a model antibiotic and it’s in vitro release rate was quantified. Drug loading was approximately 4 % for both ink compositions GC and CGC. CG Levo released over 80 % of levofloxacin within the first hour, reaching full release in 24 h, indicating inadequate control, while CGK Levo exhibited slower initial release (55 % in 15 min) followed by stabilized release after 4 h, likely due to controlled diffusion from expanded constructs. These findings demonstrate that the developed hydrogel inks and optimized printing parameters can produce scaffolds suitable for tissue engineering applications. Finally, the cell compatibility of the 3D-printed constructs was confirmed with MTT assay on fibroblasts and the antimicrobial activity of the drug-loaded constructs was tested against E. coli and S. aureus, showing an increase of the bacteria free zone from 8 ± 0.4 mm of the control against E. coli up to 16.4 ± 0.37 mm in the presence of the KOH-treated CG Levo printed construct.

Regulation of physicochemical properties of alginate-based hydrogels and preliminary applications in wound healing.

Alginate (Alg) hydrogels have demonstrated great potential in drug delivery, wound dressings, and tissue engineering. However, the practical applications of conventional Alg hydrogels suffer from rapid degradation, insufficient controlled drug release, and poor adhesion to tissues. In this paper, the physicochemical properties of Alg hydrogels were comprehensively modulated through chemical modification and the incorporation of various polymers. The results showed that introducing neutral polymers stabilized Alg hydrogels at room temperature. However, this stabilizing effect did not persist at 37 °C. The cationic chitosan (CS) can bind to Alg through electrostatic interaction. The incorporation of CS substantially improved the stability of Alg hydrogels and remarkably prolonged the release of BSA from hydrogels to 14 days at 37 °C. Meanwhile, introducing dopamine (DA)-modified Alg enhanced the adhesion of hydrogel to porcine skin. The optimized hydrogels were utilized to encapsulate platelet-rich plasma (PRP). The PRP-loaded composite hydrogel (2 wt% Alg, with a Ca2+/carboxyl group molar ratio of 0.2, a DA/carboxyl group molar ratio of 0.2, and a CS content of 30 % of Alg) exhibited an excellent therapeutic effect in the healing of rabbit shoulder cuff injury. These findings provide valuable insights into the modulation of physicochemical properties of hydrogels for biomedical applications.

Biocompatible Electrospun Hydrogel Fibers for Advanced Wound Healing Therapies.

Wound healing is a complex cascade and is governed through a number of crucial factors. Conventional wound dressing possesses numerous limitations which hinder wound healing process and may result in serious infections and even mortality. A lot of effort have been put in through researchers to develop a multifaceted dressing which can address these limitations and facilitate accelerated wound healing. Among various newly developed dressings, electrospun hydrogel nanofibers have emerged as a promising class of biomaterials for advanced wound care and tissue engineering applications. These biomimetic fibers closely mimic the architect of the native extracellular matrix, providing an optimal environment that facilitates cellular proliferation and fast generation required for effective wound healing. Electrospinning offers versatility in precisely controlling fiber attributes such as diameter, alignment, and surface morphology and can entrap a variety of drugs with high efficacy. Recently, such dressings have advanced through the incorporation of smart features such as stimuli-responsive components, real-time wound monitoring sensors, and smart closed-loop systems. The electrospun hydrogels are bestowed with extreme porosity, water-retention attribute, biocompatibility, and modified drug release which make them superior over other wound dressings. The review gives an insight of electrospun hydrogel fibers and their application in wound healing and the studies assessing wound healing potential with underlying mechanisms have been critically analysed. Electrospun hydrogel fibers have significant potential to revolutionize wound care through their biomimetic structure, versatile customization, and capacity for integrating therapeutic and sensing capabilities, outlining future research directions toward next-generation wound care products.

Biomolecule-functionalized exfoliated-graphene and graphene oxide as heteronucleants of nanocrystalline apatites to make hybrid nanocomposites with tailored mechanical, luminescent, and biological properties

Nanocrystalline apatite (Ap), known for its exceptional biological properties, faces limitations in hard tissue engineering due to its poor mechanical properties. To overcome this limitation, we investigated the preparation of nanocomposites through heterogeneous nucleation of calcium phosphate on exfoliated graphene (G) and graphene oxide (GO) flakes, selected for their outstanding mechanical properties. The flakes were treated (functionalized) with amino acids of varying isoelectric points—namely L-Arginine (Arg), L-Alanine (Aln) and L-Aspartic acid (Asp)— as well as citrate (Cit) molecules. Furthermore, Tb3+ was incorporated into the formulations to introduce luminescence and further enrich the functionality of the composite. The synthesis was conducted using the sitting drop vapor diffusion method. Functionalized GO/Ap nanocomposites significantly improved roughness, adhesion forces and elastic modulus compared to Ap and G-based particles. GO-Asp-Ap-Tb nanocomposites exhibited the highest roughness (163.8 ± 116.2 nm), while G-Cit-Ap had the lowest (6.8 ± 5.6 nm). In terms of adhesion force, GO-Cit-Ap-Tb reached the highest value (31.06 ± 13.3 nN), while G-Arg-Ap had the lowest (3.7 ± 1.8 nN) compared to Ap (13.6 ± 3.2 nN). For the elastic modulus, GO-Aln-Ap-Tb demonstrated the greatest stiffness (3489 ± 101.01 MPa) compared to Ap (30.2 ± 6.5 MPa), while G-Aln-Ap-Tb showed the lowest (17.2 ± 8.4 MPa). Concerning their luminescence, regardless of G/Ap and GO/Ap, the relative luminescence intensities depended on the biomolecule used and decreased in the order Arg > Aln >Asp and Cit. Furthermore, G/Ap and GO/Ap nanocomposites demonstrated good biocompatibility on murine mesenchymal stem cells at low concentrations, showing cell viabilities exceeding 80% at 0.1 μg/mL. This research offers a novel approach to enhancing the mechanical properties of apatites while preserving their good biocompatibility properties and introducing new functionalities (i.e. luminescence) in the composites, thereby expanding their range of applications in hard tissue engineering.

Application of smart hydrogels scaffolds for bone tissue engineering

Application of smart hydrogels scaffolds for bone tissue engineering

A drug-loaded nano chitosan/hyaluronic acid hydrogel system as a cartilage tissue engineering scaffold for drug delivery

Cartilage lesions, especially osteoarthritis (OA), usually arise from aging, trauma, or obesity and require medical intervention due to the damaged site's inflammation and the cartilage tissue's poor self-healing capacity. This study aimed to prepare a drug-loaded nanoparticle hydrogel system with anti-inflammatory and chondroprotective effects to treat OA. First, hyaluronic acid (HA) was oxidized to create aldehyde functional groups and then cross-linked with adipic acid dihydrazide (ADH) to form a hydrogel. Next, chitosan nanoparticles (CS NPs) loaded with an anti-inflammatory molecule (fisetin) and or a chondrogenic and chondroprotective agent (kartogenin) were incorporated into the hyaluronan hydrogel to improve the release profile of the drug and increase its retention time in the joint cavity. Incorporating drug-loaded NPs into the hyaluronan hydrogel provided the hydrogel with controlled release features and improved properties. In addition, the real-time PCR (Polymerase chain reaction) results showed that the hyaluronan hydrogel containing both drug-loaded NPs performed better than either constituent alone on an in vitro model of OA. Finally, based on the results of in vitro evaluation, this drug-loaded nanoparticle hydrogel system can be a promising technique for treating OA by rapidly suppressing inflammation and supporting cartilage regeneration and requires further investigation in an animal model of OA. Meanwhile, this study investigated, for the first time, the effect of the simultaneous use of fisetin and kartogenin together with a nano CS/HA hydrogel system to treat OA.

Review on Hydrogel Based Systems and their use in Drug Delivery for Wound Healing &amp; Wound Management

Abstract: The largest organ of the human body, the skin, shields the body from the outside environment. Despite having a great capacity for regeneration, major skin abnormalities cannot heal on their own and must be covered with artificial skin. In recent years, significant advancements have been achieved in the area of skin tissue engineering to create novel skin replacements. Because of their porous as well as moisturized polymeric structural composition, hydrogels are one of the choices with the greatest ability to imitate the natural skin microenvironment. Naturally derived polymers, synthesized polymers, polymerizable synthetic monomolecules, as well as mixtures of natural and synthesized polymers, can all be used to create hydrogels. They can be used to assist in the regeneration as well as repair of the wounded dermis, epidermis or else both by dressing various wounds permanently or temporarily. Hydrogels possess distinct properties like lightweight, stretchable, biocompatible, and biodegradable; they have the potential to be incorporated as flexible solutions for the care of chronic wounds. Additionally, these characteristics make hydrogels appropriate for use in the pharmaceutical and medical industries. Physical, chemical, and hybrid bonding are all involved in the creation of hydrogels. Several processes, including solution casting, solution mixing, bulk crosslinking polymerization, the free radical mechanism, radiation therapy, and the development of interpenetrating networks, are used to create the bonding. This review primarily focuses on the type of wounds with phases in wound healing and the many kinds of hydrogels based on cross-linking, ionic charge, physical properties, source etc., and it also describes potential fabrication techniques for hydrogel design in biomedical applications, drug delivery as well as wound management hydrogel systems. Hydrogel-based systems for wound recovery and management are described, as well as current research &amp; future prospective of hydrogel-based drug delivery systems in wound healing for topical applications.

Fabrication, characterisation, physicochemical and biological studies of gelatin/PVA/ silk fibre with manganese substituted hydroxyapatite scaffold for bone tissue engineering application

In recent years, researchers have been aiming for the development of multifunctional materials to repair bone tissue. The development of metal, ceramic, glass, and composite implants is the subject of interest in bone tissue engineering. Among these, HAP (ceramic) is either combined with other components, such as polymers or doped with ions to give improved properties or to add novel characteristics. The present study is focused on fabricating a novel scaffold with the required properties. Here gelatin/PVA/SF-Mn-HAP (MGPS) was fabricated by electrospinning to prepare a nano-level scaffold. The manganese-hydroxyapatite (Mn-HAP) was prepared by hydrothermal method. The nano scaffold was fabricated using various wt % (20, 40, 60) of Mn-HAP (Ca5-x Mnx (PO4)3 OH) (x = 0.1, 0.5) with gelatin/PVA/silk fibre. The fabricated nano scaffold phase formation was confirmed by X-ray diffraction (XRD), the functional group belonging to the nano scaffold was confirmed by Fourier transform infrared spectroscopy (FTIR), the topography of the nano scaffold was seen by scanning electron microscopy and the composition of elements was noted from energy dispersive X-ray analysis (EDAX). From the results, the fabricated scaffold MGPS 16 (60 wt% of Mn-HAP (x = 0.5 M) with gelatin-PVA-silk fibre) showed the highest tensile strength of 95.61 MPa. The antimicrobial activity of MGPS 16 showed the zone of inhibition against S. aureus – 62 ± 1.36 mm,E. coli – 71 ± 1.24 mm and C. albicans – 70 ± 1.22 mm. The hemolytic (%) of the MGPS 16 was 1.86 %. The SEM images of biomineralized samples showed the formation of apatite on the surface of the nano-composite.

Role of crosslinkers in advancing chitosan-based biocomposite scaffolds for bone tissue engineering: A comprehensive review.

Bone tissue engineering (BTE) aims to repair and regenerate damaged bone tissue by combining cells, scaffolds, and signaling molecules. Various macromolecules, including natural polymers like chitosan (CS), collagen, hyaluronic acid, and alginate, as well as synthetic polymers such as polyethylene glycol and polylactic acid, are used in scaffold fabrication. Among these, CS holds significant potential in BTE due to its biocompatibility, biodegradability, and other features. The inherent mechanical weaknesses of CS-based scaffolds require the implementation of crosslinking strategies to improve their stability and overall performance. Physical crosslinkers like ultra-violet irradiation and freeze-thaw cycles are biocompatible but offer limited mechanical strength. Chemical crosslinkers like glutaraldehyde significantly improve mechanical strength, but they may induce cytotoxicity. We briefly outline here the critical role of physical and chemical crosslinkers in improving the physicochemical properties, mechanical strength, biocompatibility, and biological functions of CS-based scaffolds, including effective bone regeneration. The influence of crosslinking on the CS-based scaffolds' bioactivity, including the controlled release of bioactive molecules, is also discussed. A thorough understanding of crosslinker chemistry and application in CS-based scaffolds is essential for advancing bone regeneration therapies.

Bone regeneration in rabbit cranial defects: 3D printed polylactic acid scaffolds gradually enriched with marine bioderived calcium phosphate

ObjectiveThis study aimed to evaluate the in vivo biocompatibility, mechanical performance and osteoconductive potential of 3D-printed polylactic acid (PLA) scaffolds enriched with marine bioderived calcium phosphate (bioCaP) for bone tissue engineering. Materials and MethodsPLA-bioCaP composite scaffolds were specifically designed for the rabbit cranial defect model by 3D printing, with a uniform distribution of open square-shaped pores and contributions in bioCaP. Physicochemical and mechanical characterization and the evaluation of biological response are presented. ResultsThe scaffolds demonstrated mechanical properties comparable to human bones, integration with the host bone, and osteoconductive behavior promoting cell ingrowth from the defect edge. Strong mineralized tissue ingrowth through the scaffolds’ pores was observed, providing notable support to the host bone. In quantitative terms, micro-CT and histomorphometry analysis post-implantation revealed no significant differences in bone regeneration across all groups. ConclusionThe 3D-printed scaffolds with perpendicular patterning, open porosity, and proposed composition displayed satisfactory mechanical properties, biocompatibility, and osteoconductive response. The scaffolds promoted bone regeneration at similar levels as the PLA. The highest contribution of bioCaP promoted a positive influence in certain histomorphometric parameters; however, it did not significantly improve their osteogenic capability. Further research is required to optimize scaffold composition and enhance their osteogenic potential. Clinical RelevanceThis study presents a significant advancement in bone tissue engineering through the development of personalized composite scaffolds for bone-related applications. The clinical implications of this research are profound, especially considering the increasing demand for functional bone regeneration technologies capable of producing cost-effective producing cost-effective customized scaffolds.

Poly acrylic acid patterning by electron beam lithography

Poly acrylic acid (PAA) is a polymer and a derivative of acrylic acid that is a superabsorbent, being able to absorb and retain water, and swell many times beyond its original volume. This property classifies it into a group of polymers called hydrogels. Hydrogels are being investigated in emerging applications such as drug delivery, biosensors, tissue engineering, wound healing bandages, and more. The ability to lithographically pattern hydrogel materials to specific dimensions at the micro and nanoscales can be very useful in devices and sensors. Limited work has been done on characterizing PAA for lithographic purposes, and so, this work investigates the ability to pattern PAA by electron beam lithography (EBL). PAA is interesting in that its carrier solvent, developer, and remover are all water alone, which may make it attractive for processes or materials that cannot tolerate solvents, acids, and bases used with other common EBL resists. PAA behaves as a negative tone resist with a relatively low base dose of 75 μC/cm2 at 100 kV acceleration voltage. The resolution is limited to 1.8 μm due to a low contrast of 1.29. However, PAA may still have many uses at that resolution where the positioning and dimension control of a hydrogel could be useful. Furthermore, PAA can successfully be used for pattern transfer with either a metal liftoff process or a silicon plasma etch.

Spatiotemporal characterization of extracellular matrix maturation in human artificial stromal-epithelial tissue substitutes

Abstract Background Tissue engineering techniques offer new strategies to understand complex processes in a controlled and reproducible system. In this study, we generated bilayered human tissue substitutes consisting of a cellular connective tissue with a suprajacent epithelium (full-thickness stromal-epithelial substitutes or SESS) and human tissue substitutes with an epithelial layer generated on top of an acellular biomaterial (epithelial substitutes or ESS). Both types of artificial tissues were studied at sequential time periods to analyze the maturation process of the extracellular matrix. Results Regarding epithelial layer, ESS cells showed active proliferation, positive expression of cytokeratin 5, and low expression of differentiation markers, whereas SESS epithelium showed higher differentiation levels, with a progressive positive expression of cytokeratin 10 and claudin. Stromal cells in SESS tended to accumulate and actively synthetize extracellular matrix components such as collagens and proteoglycans in the stromal area in direct contact with the epithelium (zone 1), whereas these components were very scarce in ESS. Regarding the basement membrane, ESS showed a partially differentiated structure containing fibronectin-1 and perlecan. However, SESS showed higher basement membrane differentiation, with positive expression of fibronectin 1, perlecan, nidogen 1, chondroitin-6-sulfate proteoglycans, agrin, and collagens types IV and VII, although this structure was negative for lumican. Finally, both ESS and SESS proved to be useful tools for studying metabolic pathway regulation, revealing differential activation and upregulation of the transforming growth factor-β pathway in ESS and SESS. Conclusions These results confirm the relevance of epithelial-stromal interaction for extracellular matrix development and differentiation, especially regarding basement membrane components, and suggest the usefulness of bilayered artificial tissue substitutes to reproduce ex vivo the extracellular matrix maturation and development process of human tissues. Graphical Abstract