Antibacterial and Bioactive Surface Modifications of Titanium Implants by PCL/TiO₂ Nanocomposite Coatings

Polymeric nanocomposites in a biological interface: From a molecular view to final applications

Polymeric nanocomposites have been valuable materials for the pharmaceutical and biomedical fields because they associate the unique properties of a material on a nanoscale with a polymeric matrix, with a synergistic outcome that improves their physical, chemical, and mechanical properties. Understanding the nature of the physical and chemical interactions and effects that take place at the polymer-nanomaterial interface is crucial to predict and explain how the nanocomposite behaves when set forth a health-related application and faces a biological interface. Therefore, this review aimed to assemble and examine experimental articles in which the molecular-level interaction between nanomaterials and polymer matrices were determinants of the biological outcome. For health applications, the nanocomposite systems were found to be most applied as antimicrobials, for tissue engineering, and for drug delivery. A plethora of biocompatible polymers have been reported, although for nanomaterials the most distinguished effects were attained with metal and metal oxide nanoparticles. The bioactivity of the nanocomposite was found to be dependent on features such as: colloidal size, release, and disintegration of the nanoparticle, controlled by the polymer matrix; hydrophilicity, degree of crosslinking, porosity, mechanical strength, and stability/responsiveness of the polymer, modified by the nanofiller; and the final charge and functional groups available at the whole nanocomposite surface. As a result, researchers can gather insights to design and characterize advanced polymeric nanocomposites with optimized performance for use in biomedical devices, drug delivery systems, and other therapeutic applications.

Development of Curcumin-Loaded TiO2-Reinforced Chitosan Monofilaments for Biocompatible Surgical Sutures

Sutures provide mechanical support for wound closure after various traumas and surgical operations. Absorbable sutures are increasingly favored as they eliminate the need for secondary procedures and minimize additional damage to the wound site. In this study, chitosan sutures were produced using the dry jet-wet spinning method, achieving number 7-0 sutures (approximately 76 μm diameter) with a homogeneous surface. FTIR analysis demonstrated molecular interactions between chitosan and TiO2 or curcumin, confirming successful incorporation. The addition of 3% TiO2 increased the tensile strength of chitosan sutures by 12.32%, reaching 189.41 MPa. Morphological analysis revealed smooth surfaces free of pores and bubbles, confirming the production of high-quality sutures. Radical scavenging activity analysis showed that curcumin-loaded sutures exhibited 43% scavenging ability after 125 h, which was significantly higher compared to pure chitosan sutures. In vitro antibacterial tests demonstrated that curcumin-loaded sutures provided 98.87% bacterial inactivation against S. aureus within 24 h. Additionally, curcumin release analysis showed a cumulative release of 77% over 25 h. The bioactivity of the sutures was verified by hydroxyapatite layer formation after incubation in simulated body fluid, supporting their potential for tissue regeneration. These findings demonstrate that TiO2 reinforcement and curcumin loading significantly enhance the functional properties of chitosan sutures, making them strong candidates for biocompatible and absorbable surgical applications.

Enhanced healing of critical-sized bone defects using degradable scaffolds with tailored composition through immunomodulation and angiogenesis

The impact of orthopedic scaffolds on bone defect healing, particularly the late-stage bone remodeling process, is pivotal for the therapeutic outcome. This study applies fadditively manufactured scaffolds composed of hydroxyapatite-doped poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (HA-PELGA) with varying properties to treat rat calvarial defects, elucidating their significant role in bone remodeling by modulating physiological responses. We engineered two scaffolds with different polylactic acid (PLA) to polyglycolic acid (PGA) ratio (9/1 and 18/1) to vary in hydrophobicity, degradation rate, mechanical properties, and structural stability. These variations influenced physiological responses, including osteogenesis, angiogenesis, and immune reactions, thereby guiding bone remodeling. Our findings show that the HA-PELGA(18/1) scaffold, with a slower degradation rate, supported bulk bone formation due to a stable microenvironment. Conversely, the HA-PELGA(9/1) scaffold, with a faster degradation rate and more active interfaces, facilitated the formation of a thin bone layer and higher bone infiltration. This study demonstrates these degradable scaffolds help to promote bone healing and reveals how scaffold properties influence the bone remodeling process, offering a potential strategy to optimize scaffold design aiming at late-stage bone defect healing.

Hydroxyapatite-based coatings on Mg and Ti-based implants: A detailed examination of various coating methodologies

Metallic implants have been considered as promising alternatives to traditional implants due to their biocompatibility and favorable biodegradability properties. However, one of the major challenges in using these implants is the relatively fast degradation rate of metal alloys in the body's electrolyte environment, which can lead to early loss of performance and the release of undesirable degradation products. Applying appropriate coatings with suitable performance on the surface of metal implants can be an effective solution to control the rate of deterioration and increase their stability in the body environment. In this comprehensive study, various methods of coating metal implants with calcium phosphate or hydroxyapatite structures, including sol-gel, chemical deposition (such as hydrothermal deposition), and thermal spraying (such as plasma spray) methods have been fully investigated. The benefits and drawbacks of each of these techniques in relation to the properties of the resulting coating such as surface morphology, chemical composition, adhesion to the substrate, porosity and crystal structure, anti-corrosion performance, their impact on the biological performance of the implant in terms of biocompatibility, degradation rate control, and mechanical properties, as well as limitations related to the coating process are described. The results of this comprehensive study provide valuable and key guidance for choosing the most suitable coating and coating method according to the type of medical application considered for metal implants.

TiO2 Nanocomposite Coatings and Inactivation of Carbapenemase-Producing Klebsiella Pneumoniae Biofilm-Opportunities and Challenges

The worldwide increase of multidrug-resistant Gram-negative bacteria is a global threat. The emergence and global spread of Klebsiella pneumoniae carbapenemase- (KPC-) producing Klebsiella pneumoniae represent a particular concern. This pathogen has increased resistance and abilities to persist in human reservoirs, in hospital environments, on medical devices, and to generate biofilms. Mortality related to this microorganism is high among immunosuppressed oncological patients and those with multiple hospitalizations and an extended stay in intensive care. There is a severe threat posed by the ability of biofilms to grow and resist antibiotics. Various nanotechnology-based strategies have been studied and developed to prevent and combat serious health problems caused by biofilm infections. The aim of this review was to evaluate the implications of nanotechnology in eradicating biofilms with KPC-producing Klebsiella pneumoniae, one of the bacteria most frequently associated with nosocomial infections in intensive care units, including in our department, and to highlight studies presenting the potential applicability of TiO2 nanocomposite materials in hospital practice. We also described the frequency of the presence of bacterial biofilms on medical surfaces, devices, and equipment. TiO2 nanocomposite coatings are one of the best long-term options for antimicrobial efficacy due to their biocompatibility, stability, corrosion resistance, and low cost; they find their applicability in hospital practice due to their critical antimicrobial role for surfaces and orthopedic and dental implants. The International Agency for Research on Cancer has recently classified titanium dioxide nanoparticles (TiO2 NPs) as possibly carcinogenic. Currently, there is an interest in the ecological, non-toxic synthesis of TiO2 nanoparticles via biological methods. Biogenic, non-toxic nanoparticles have remarkable properties due to their biocompatibility, stability, and size. Few studies have mentioned the use of nanoparticle-coated surfaces as antibiofilm agents. A literature review was performed to identify publications related to KPC-producing Klebsiella pneumoniae biofilms and antimicrobial TiO2 photocatalytic nanocomposite coatings. There are few reviews on the antibacterial and antibiofilm applications of TiO2 photocatalytic nanocomposite coatings. TiO2 nanoparticles demonstrated marked antibiofilm activity, but being nano in size, these nanoparticles can penetrate cell membranes and may initiate cellular toxicity and genotoxicity. Biogenic TiO2 nanoparticles obtained via green, ecological technology have less applicability but are actively investigated.

Biodegradable implant application: Electrodeposition of HA/TiO2/ZrO2 coating onto Zn-composite substrates

Zinc has currently emerged as a promising biodegradable metal due to its good biocompatible property and promising degradation behaviour. Additionally, inadequate mechanical strength and a lower cell viability value fall short of what is needed for biodegradable implants. In this work, we used the stir-casting process to create a biodegradable Zn-1Mg-1Cu-1HA (ZHA) and Zn-1Mg-1Cu-1ZrO2 (ZZR) composite onto which ceramics composite coating is done by electrodeposition technique to enhance the biocompatibility. The as-cast sample has uniformly distributed fine MgZn2 and CuZn2 phases in a α-Zn matrix, according to microstructural analysis. The mechanical test confirms that ZZR composite exhibited high tensile and compressive properties, including compressive yield strength of 369.562 MPa, a yield tensile strength of 88.725 MPa and ultimate tensile strength of 116.21 MPa. The result of potentiodynamic polarization test shows that the coated ZZR composite sample gives a corrosion rate value of 0.112 mm/year. From immersion tests, the degradation rate obtained a much lower value after immersing the sample in PBS solution for 55 days (0.067 mm/year). Moreover, an extract of coated ZZR composite shows good cell viability in comparison to the uncoated sample at a concentration of 25%, 50% and 75%. Also, the hemolysis percentage for coated ZZR sample is lower than the other prepared uncoated sample (3.072%) Overall, the result obtained proves that the coated ZZR composite sample can be expected as a capable material for implant application.

Resorbable Membranes for Guided Bone Regeneration: Critical Features, Potentials, and Limitations

Lack of horizontal and vertical bone at the site of an implant can lead to significant clinical problems that need to be addressed before implant treatment can take place. Guided bone regeneration (GBR) is a commonly used surgical procedure that employs a barrier membrane to encourage the growth of new bone tissue in areas where bone has been lost due to injury or disease. It is a promising approach to achieve desired repair in bone tissue and is widely accepted and used in approximately 40% of patients with bone defects. In this Review, we provide a comprehensive examination of recent advances in resorbable membranes for GBR including natural materials such as chitosan, collagen, silk fibroin, along with synthetic materials such as polyglycolic acid (PGA), polycaprolactone (PCL), polyethylene glycol (PEG), and their copolymers. In addition, the properties of these materials including foreign body reaction, mechanical stability, antibacterial property, and growth factor delivery performance will be compared and discussed. Finally, future directions for resorbable membrane development and potential clinical applications will be highlighted.

MWCNTs-TiO2 Incorporated-Mg Composites to Improve the Mechanical, Corrosion and Biological Characteristics for Use in Biomedical Fields

This study attempts to synthesize MgZn/TiO₂-MWCNTs composites with varying TiO₂-MWCNT concentrations using mechanical alloying and a semi-powder metallurgy process coupled with spark plasma sintering. It also aims to investigate the mechanical, corrosion, and antibacterial properties of these composites. When compared to the MgZn composite, the microhardness and compressive strength of the MgZn/TiO₂-MWCNTs composites were enhanced to 79 HV and 269 MPa, respectively. The results of cell culture and viability experiments revealed that incorporating TiO₂-MWCNTs increased osteoblast proliferation and attachment and enhanced the biocompatibility of the TiO₂-MWCNTs nanocomposite. It was observed that the corrosion resistance of the Mg-based composite was improved and the corrosion rate was reduced to about 2.1 mm/y with the addition of 10 wt% TiO₂-1 wt% MWCNTs. In vitro testing for up to 14 days revealed a reduced degradation rate following the incorporation of TiO₂-MWCNTs reinforcement into a MgZn matrix alloy. Antibacterial evaluations revealed that the composite had antibacterial activity, with an inhibition zone of 3.7 mm against Staphylococcus aureus. The MgZn/TiO₂-MWCNTs composite structure has great potential for use in orthopedic fracture fixation devices.

Evaluation of biodegradable Zn-1Mg-1Mn and Zn-1Mg-1Mn-1HA composites with a polymer-ceramics coating of PLA/HA/TiO2 for orthopaedic applications

Zn is a promising biodegradable metal that shows huge potential as bioresorbable implant material as it possesses outstanding biocompatibility and high corrosion resistance than Mg. However, the low value of mechanical strength and hardness has hugely restricted its application. Moreover, incorporating alloying elements have typically magnified its mechanical properties. In the current study, the effect of the alloying component Mn and HA on the Zn-Mg composite and also the effect of polymer-ceramics nanofiber coating on the composite sample was studied. The result shows that the current studied samples were mainly comprised of a primary Zn matrix and a secondary phase of Mg2Zn11. The prepared sample shows very high compressive yield strength (CYS 228 MPa) and hardness (83 HV). The value of corrosion rates of the as-cast Zn-1Mg-1Mn-1HA sample was higher in comparison to that of the as-cast Zn-1Mg-1Mn sample, but after the polymer-ceramics nanofiber coating formation of PLA/HA/TiO2, the values were reduced to a more significant extent and achieved values of 0.01484 mm/year from 0.01892 mm/year in electrochemical tests. Moreover, the coated and uncoated sample shows outstanding hemocompatibility for both samples, but the minimum value is obtained for coated Zn-1Mg-1Mn-1HA sample (2.251%). The viability of MG63 cells cultured in different diluted extracts (25% and 50% extract) of the coated Zn-1Mg-1Mn-1HA sample reached a value greater than 90%, which displayed no possible cytotoxicity for biomedical applications.

Scaffolds in the microbial resistant era: Fabrication, materials, properties and tissue engineering applications

Due to microbial infections dramatically affect cell survival and increase the risk of implant failure, scaffolds produced with antimicrobial materials are now much more likely to be successful. Multidrug-resistant infections without suitable prevention strategies are increasing at an alarming rate. The ability of cells to organize, develop, differentiate, produce a functioning extracellular matrix (ECM) and create new functional tissue can all be controlled by careful control of the extracellular microenvironment. This review covers the present state of advanced strategies to develop scaffolds with antimicrobial properties for bone, oral tissue, skin, muscle, nerve, trachea, cardiac and other tissue engineering applications. The review focuses on the development of antimicrobial scaffolds against bacteria and fungi using a wide range of materials, including polymers, biopolymers, glass, ceramics and antimicrobials agents such as antibiotics, antiseptics, antimicrobial polymers, peptides, metals, carbon nanomaterials, combinatorial strategies, and includes discussions on the antimicrobial mechanisms involved in these antimicrobial approaches. The toxicological aspects of these advanced scaffolds are also analyzed to ensure future technological transfer to clinics. The main antimicrobial methods of characterizing scaffolds' antimicrobial and antibiofilm properties are described. The production methods of these porous supports, such as electrospinning, phase separation, gas foaming, the porogen method, polymerization in solution, fiber mesh coating, self-assembly, membrane lamination, freeze drying, 3D printing and bioprinting, among others, are also included in this article. These important advances in antimicrobial materials-based scaffolds for regenerative medicine offer many new promising avenues to the material design and tissue-engineering communities.

Molecularly Imprinted Membrane Produced by Electrospinning for β-Caryophyllene Extraction

Molecularly imprinted membrane of β-caryophyllene (MIM-βCP) was fabricated incorporating β-caryophyllene molecularly imprinted polymer nanoparticles (βCP-NP) into polycaprolactone (PCL) fibers via electrospinning. The βCP-NP were synthesized by precipitation polymerization using the βCP as a template molecule and acrylic acid as a functional monomer in the proportion of 1:4 mol, respectively. Atomic force microscopy images and X-ray diffraction confirmed the nanoparticles' incorporation into MIM-βCP. MIM-βCP functionalization was evaluated by gas chromatography. The binding capacity was 1.80 ± 0.05 μmol/cm², and the selectivity test was performed with a mixing solution of βCP and caryophyllene oxide, as an analog compound, that extracted 77% of the βCP in 5 min. The electrospun MIM-βCP can be used to detect and extract the βCP, applications in the molecular sieve, and biosensor production and may also contribute as an initial methodology to enhance versatile applications in the future, such as in the treatment of skin diseases, filters for extraction, and detection of βCP to prevent counterfeiting of commercial products, and smart clothing with insect-repellent properties.

Titanium(IV) Oxo-Complex with Acetylsalicylic Acid Ligand and Its Polymer Composites: Synthesis, Structure, Spectroscopic Characterization, and Photocatalytic Activity

The titanium oxo complexes are widely studied, due to their potential applications in photocatalytic processes, environmental protection, and also in the biomedical field. The presented results concern the oxo complex synthesized in the reaction of titanium(IV) isobutoxide and acetylsalicylic acid (Hasp), in a 4:1 molar ratio. The structure of isolated crystals was solved using the single-crystal X-ray diffraction method. The analysis of these data proves that [Ti₄O₂(OⁱBu)₁₀(asp)₂]·H₂O (1) complex is formed. Moreover, the molecular structure of (1) was characterized using vibrational spectroscopic techniques (IR and Raman), ¹³C NMR, and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). The photocatalytic activity of the synthesized complex was determined with the use of composite foils produced by the dispersion of (1) micrograins, as the inorganic blocks, in a polycaprolactone (PCL) matrix (PCL + (1)). The introduction of (1) micrograins to the PCL matrix caused the absorption maximum shift up to 425–450 nm. The studied PCL + (1) composite samples reveal good activity toward photodecolorization of methylene blue after visible light irradiation.

Nanomaterial reinforced composite for biomedical implants applications: a mini-review

There is heavy demand for suitable implant materials with improved mechanical and biological properties. Classically, the demand was catered by conventional materials like metals, alloys, and polymer-based materials. Recently, nanomaterial reinforced composites have played a significant role in replacing conventional materials due to their excellent properties such as biocompatibility, bioactivity, high strength to weight ratio, long life, corrosion & wear resistance, and tailor-ability. Herein, we composed a systematic focus review on the role of nanoparticles in the form of composite materials for the advancements in orthopedic implants. Several nano materials-based reinforcements have been reviewed with various matrix materials, including metals, alloys, ceramics, composites, and polymers for biomedical implant applications. Moreover, the improved biological properties, mechanical properties, and other functionalities like infection resistance, drug delivery at the target, sensing, and detection of bone diseases, and corrosion & wear resistance are elaborated. At last, a particular focus has been given to the un-resolved challenges in orthopedic implant development.

Recent Advancements in Materials and Coatings for Biomedical Implants

Metallic materials such as stainless steel (SS), titanium (Ti), magnesium (Mg) alloys, and cobalt-chromium (Co-Cr) alloys are widely used as biomaterials for implant applications. Metallic implants sometimes fail in surgeries due to inadequate biocompatibility, faster degradation rate (Mg-based alloys), inflammatory response, infections, inertness (SS, Ti, and Co-Cr alloys), lower corrosion resistance, elastic modulus mismatch, excessive wear, and shielding stress. Therefore, to address this problem, it is necessary to develop a method to improve the biofunctionalization of metallic implant surfaces by changing the materials' surface and morphology without altering the mechanical properties of metallic implants. Among various methods, surface modification on metallic surfaces by applying coatings is an effective way to improve implant material performance. In this review, we discuss the recent developments in ceramics, polymers, and metallic materials used for implant applications. Their biocompatibility is also discussed. The recent trends in coatings for biomedical implants, applications, and their future directions were also discussed in detail.

Nanofiber Polymers for Coating Titanium-Based Biomedical Implants

The excellent combination of properties has seen a steep increase in the demand for titanium (Ti)-based material as biomedical implant devices. However, some features that promote biocompatibility are found to be lacking in Ti implants. The use of polymer nanofiber (NF) coating on the surfaces of the implants has been proven to remedy these setbacks. In particular, electrospun NFs are versatile as natural extracellular matrix mimics and as facilitators in the biocompatibility function of Ti-based implants. Therefore, various properties of Ti implants coated with polymer NFs and the correlations among these properties are explored in this review. Synthetic polymers are favorable in tissue engineering applications because they are biocompatible and have low toxicity and degradation rates. Several approved synthetic polymers and polymer hybrids have been electrospun onto Ti implant surfaces to successfully improve the biomedical applicability of the implants with regard to their physical (including diameter and porosity), chemical (including corrosion resistance), mechanical (including elastic modulus, strength and ductility) and biological properties (including tissue integration, antimicrobial and cytotoxicity).

Advanced Surface Modification for 3D-Printed Titanium Alloy Implant Interface Functionalization

With the development of three-dimensional (3D) printed technology, 3D printed alloy implants, especially titanium alloy, play a critical role in biomedical fields such as orthopedics and dentistry. However, untreated titanium alloy implants always possess a bioinert surface that prevents the interface osseointegration, which is necessary to perform surface modification to enhance its biological functions. In this article, we discuss the principles and processes of chemical, physical, and biological surface modification technologies on 3D printed titanium alloy implants in detail. Furthermore, the challenges on antibacterial, osteogenesis, and mechanical properties of 3D-printed titanium alloy implants by surface modification are summarized. Future research studies, including the combination of multiple modification technologies or the coordination of the structure and composition of the composite coating are also present. This review provides leading-edge functionalization strategies of the 3D printed titanium alloy implants.

Engineered titania nanomaterials in advanced clinical applications

Significant advancement in the field of nanotechnology has raised the possibility of applying potent engineered biocompatible nanomaterials within biological systems for theranostic purposes. Titanium dioxide (titanium(IV) oxide/titania/TiO2) has garnered considerable attention as one of the most extensively studied metal oxides in clinical applications. Owing to the unique properties of titania, such as photocatalytic activity, excellent biocompatibility, corrosion resistance, and low toxicity, titania nanomaterials have revolutionized therapeutic approaches. Additionally, titania provides an exceptional choice for developing innovative medical devices and the integration of functional moieties that can modulate the biological responses. Thus, the current review aims to present a comprehensive and up-to-date overview of TiO2-based nanotherapeutics and the corresponding future challenges.

Antimicrobial and Antibiofilm Coating of Dental Implants—Past and New Perspectives

Regarded as one of the best solutions to replace missing teeth in the oral cavity, dental implants have been the focus of plenty of studies and research in the past few years. Antimicrobial coatings are a promising solution to control and prevent bacterial infections that compromise the success of dental implants. In the last few years, new materials that prevent biofilm adhesion to the surface of titanium implants have been reported, ranging from improved methods to already established coating surfaces. The purpose of this review is to present the developed antimicrobial and antibiofilm coatings that may have the potential to reduce bacterial infections and improve the success rate of titanium dental implants. All referred coating surfaces showed high antimicrobial properties with effectiveness in biofilm control, while maintaining implant biocompatibility. We expect that by combining the use of oligonucleotide probes as a covering material with novel peri-implant adjuvant therapies, we will be able to avoid the downsides of other covering materials (such as antibiotic resistance), prevent bacterial infections, and raise the success rate of dental implants. The existing knowledge on the optimal coating material for dental implants is limited, and further research is needed before more definitive conclusions can be drawn.

Analytical Techniques for the Characterization of Bioactive Coatings for Orthopaedic Implants

The development of bioactive coatings for orthopedic implants has been of great interest in recent years in order to achieve both early- and long-term osseointegration. Numerous bioactive materials have been investigated for this purpose, along with loading coatings with therapeutic agents (active compounds) that are released into the surrounding media in a controlled manner after surgery. This review initially focuses on the importance and usefulness of characterization techniques for bioactive coatings, allowing the detailed evaluation of coating properties and further improvements. Various advanced analytical techniques that have been used to characterize the structure, interactions, and morphology of the designed bioactive coatings are comprehensively described by means of time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), 3D tomography, quartz crystal microbalance (QCM), coating adhesion, and contact angle (CA) measurements. Secondly, the design of controlled-release systems, the determination of drug release kinetics, and recent advances in drug release from bioactive coatings are addressed as the evaluation thereof is crucial for improving the synthesis parameters in designing optimal bioactive coatings.

Biomimetic 3D-printed PCL scaffold containing a high concentration carbonated-nanohydroxyapatite with immobilized-collagen for bone tissue engineering: enhanced bioactivity and physicomechanical characteristics

A challenging approach of three-dimensional (3D)-biomimetic scaffold design for bone tissue engineering is to improve scaffold bioactivity and mechanical properties. We aimed to design and fabricate 3D-polycaprolactone (PCL)-based nanocomposite scaffold containing a high concentration homogeneously distributed carbonated-nanohydroxyapatite (C-nHA)-particles in combination with immobilized-collagen to mimic real bone properties. PCL-scaffolds without/with C-nHA at 30%, 45%, and 60% (wt/wt) were 3D-printed. PCL/C-nHA60%-scaffolds were surface-modified by NaOH-treatment and collagen-immobilization. Physicomechanical and biological properties were investigated experimentally and by finite-element (FE) modeling. Scaffold surface-roughness enhanced by increasing C-nHA (1.7 - 6.1-fold), but decreased by surface-modification (0.6-fold). The contact angle decreased by increasing C-nHA (0.9 - 0.7-fold), and by surface-modification (0.5-fold). The zeta potential decreased by increasing C-nHA (3.2-9.9-fold). Average elastic modulus, compressive strength, and reaction force enhanced by increasing C-nHA and by surface-modification. FE modeling revealed that von Mises stress distribution became less homogeneous by increasing C-nHA, and by surface-modification. Maximal von Mises stress for 2% compression strain in all scaffolds did not exceed yield stress for bulk-material. 3D-printed PCL/C-nHA60% with surface-modification enhanced pre-osteoblast spreading, proliferation, collagen deposition, alkaline phosphatase activity, and mineralization. In conclusion, a novel biomimetic 3D-printed PCL-scaffold containing a high concentration C-nHA with surface-modification was successfully fabricated. It exhibited superior physicomechanical and biological properties, making it a promising biomaterial for bone tissue engineering.

Histologic and Histomorphometric Evaluation of a New Bioactive Liquid BBL on Implant Surface: A Preclinical Study in Foxhound Dogs

BACKGROUND

Bioactive chemical surface modifications improve the wettability and osseointegration properties of titanium implants in both animals and humans. The objective of this animal study was to investigate and compare the bioreactivity characteristics of titanium implants (BLT) pre-treated with a novel bone bioactive liquid (BBL) and the commercially available BLT-SLA active.

METHODS

Forty BLT-SLA titanium implants were placed in in four foxhound dogs. Animals were divided into two groups (n = 20): test (BLT-SLA pre-treated with BBL) and control (BLT-SLA active) implants. The implants were inserted in the post extraction sockets. After 8 and 12 weeks, the animals were sacrificed, and mandibles were extracted, containing the implants and the surrounding soft and hard tissues. Bone-to-implant contact (BIC), inter-thread bone area percentage (ITBA), soft tissue, and crestal bone loss were evaluated by histology and histomorphometry.

RESULTS

All animals were healthy with no implant loss or inflammation symptoms. All implants were clinically and histologically osseo-integrated. Relative to control groups, test implants demonstrated a significant 1.5- and 1.7-fold increase in BIC and ITBA values, respectively, at both assessment intervals. Crestal bone loss was also significantly reduced in the test group, as compared with controls, at week 8 in both the buccal crests (0.47 ± 0.32 vs 0.98 ± 0.51 mm, p < 0.05) and lingual crests (0.39* ± 0.3 vs. 0.89 ± 0.41 mm, p < 0.05). At week 12, a pronounced crestal bone loss improvement was observed in the test group (buccal, 0.41 ± 0.29 mm and lingual, 0.54 ± 0.23 mm). Tissue thickness showed comparable values at both the buccal and lingual regions and was significantly improved in the studied groups (0.82-0.92 mm vs. 33-48 mm in the control group).

CONCLUSIONS

Relative to the commercially available BLT-SLA active implants, BLT-SLA pre-treated with BBL showed improved histological and histomorphometric characteristics indicating a reduced titanium surface roughness and improved wettability, promoting healing and soft and hard tissue regeneration at the implant site.

The Composites of PCL and Tetranuclear Titanium(IV)-oxo Complexes as Materials Exhibiting the Photocatalytic and the Antimicrobial Activity

Excessive misuse of antibiotics and antimicrobials has led to a spread of microorganisms resistant to most currently used agents. The resulting global threats has driven the search for new materials with optimal antimicrobial activity and their application in various areas of our lives. In our research, we focused on the formation of composite materials produced by the dispersion of titanium(IV)-oxo complexes (TOCs) in poly(ε-caprolactone) (PCL) matrix, which exhibit optimal antimicrobial activity. TOCs, of the general formula [Ti₄O₂(OⁱBu)₁₀(O₂CR’)₂] (R’ = PhNH₂ (1), C₁₃H₉ (2)) were synthesized as a result of the direct reaction of titanium(IV) isobutoxide and 4-aminobenzoic acid or 9-fluorenecarboxylic acid. The microcrystalline powders of (1) and (2), whose structures were confirmed by infrared (IR) and Raman spectroscopy, were dispersed in PCL matrixes. In this way, the composites PCL + nTOCs (n = 5 and 20 wt.%) were produced. The structure and physicochemical properties were determined on the basis of Raman microscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), electron paramagnetic resonance spectroscopy (EPR), and UV–Vis diffuse reflectance spectroscopy (DRS). The degree of TOCs distribution in the polymer matrix was monitored by scanning electron microscopy (SEM). The addition of TOCs micro grains into the PCL matrix only slightly changed the thermal and mechanical properties of the composite compared to the pure PCL. Among the investigated PCL + TOCs systems, promising antibacterial properties were confirmed for samples of PCL + n(2) (n = 5, 20 wt.%) composites, which simultaneously revealed the best photocatalytic activity in the visible range.

Bioinspired antibacterial PVA/Melanin-TiO2 hybrid nanoparticles: the role of poly-vinyl-alcohol on their self-assembly and biocide activity

Hybrid Melanin-TiO₂ nanoparticles are promising bioinspired antibacterial agents for biomedical coatings and food-packaging fields. However, due to a very low colloidal stability, they showed a high tendency to self-aggregate and rapidly precipitate, making not easy their use in aqueous medium to produce homogeneous antimicrobial coatings or nanocomposites. A valid strategy to improve their dispersion is the combination with a hydrophilic water-soluble polymer such as poly-vinyl-alcohol (PVA), which is a good choice to improve the colloidal stability of nanoparticles and to modulate their agglomeration. In this work, we propose an in-situ synthetic approach based on the hydrothermal route, by which the hybrid Melanin-TiO₂ nanoparticles were prepared starting from the inorganic and organic precursors in the presence of PVA. Combined approach of TEM, XRD, TG/DSC, EPR and DLS techniques allows for assessing the PVA role in the formation of hybrids and on their morphological features as well as colloidal stability and aqueous dispersion. Antibacterial tests demonstrated the biocide activity of PVA/Melanin-TiO₂ nanoparticles against Escherichia coli bacterial cultures, which resulted partially influenced by the PVA content. This study provides key information on the mutual influence of organic/inorganic components on the functional properties of the final hybrid nanocomposites, contributing to define a much more far-reaching implementation in the synthesis of bioinspired polymer-based nanocomposites.

Antibacterial biomaterials in bone tissue engineering

Bone infection is a devastating disease characterized by recurrence, drug-resistance, and high morbidity, that has prompted clinicians and scientists to develop novel approaches to combat it. Currently, although numerous biomaterials that possess excellent biocompatibility, biodegradability, porosity, and mechanical strength have been developed, their lack of effective antibacterial ability substantially limits bone-defect treatment efficacy. There is, accordingly, a pressing need to design antibacterial biomaterials for effective bone-infection prevention and treatment. This review focuses on antibacterial biomaterials and strategies; it presents recently reported biomaterials, including antibacterial implants, antibacterial scaffolds, antibacterial hydrogels, and antibacterial bone cement types, and aims to provide an overview of these antibacterial materials for application in biomedicine. The antibacterial mechanisms of these materials are discussed as well.

Progress on the Fabrication and Application of Electrospun Nanofiber Composites

Nanofibers are one of the most attractive materials in various applications due to their unique properties and promising characteristics for the next generation of materials in the fields of energy, environment, and health. Among the many fabrication methods, electrospinning is one of the most efficient technologies which has brought about remarkable progress in the fabrication of nanofibers with high surface area, high aspect ratio, and porosity features. However, neat nanofibers generally have low mechanical strength, thermal instability, and limited functionalities. Therefore, composite and modified structures of electrospun nanofibers have been developed to improve the advantages of nanofibers and overcome their drawbacks. The combination of electrospinning technology and high-quality nanomaterials via materials science advances as well as new modification techniques have led to the fabrication of composite and modified nanofibers with desired properties for different applications. In this review, we present the recent progress on the fabrication and applications of electrospun nanofiber composites to sketch a progress line for advancements in various categories. Firstly, the different methods for fabrication of composite and modified nanofibers have been investigated. Then, the current innovations of composite nanofibers in environmental, healthcare, and energy fields have been described, and the improvements in each field are explained in detail. The continued growth of composite and modified nanofiber technology reveals its versatile properties that offer alternatives for many of current industrial and domestic issues and applications.

Bactericidal coating to prevent early and delayed implant-related infections

The occurrence of an implant-associated infection (IAI) with the formation of a persisting bacterial biofilm remains a major risk following orthopedic biomaterial implantation. Yet, progress in the fabrication of tunable and durable implant coatings with sufficient bactericidal activity to prevent IAI has been limited. Here, an electrospun composite coating was optimized for the combinatorial and sustained delivery of antibiotics. Antibiotics-laden poly(ε-caprolactone) (PCL) and poly`1q`(lactic-co glycolic acid) (PLGA) nanofibers were electrospun onto lattice structured titanium (Ti) implants. In order to achieve tunable and independent delivery of vancomycin (Van) and rifampicin (Rif), we investigated the influence of the specific drug-polymer interaction and the nanofiber coating composition on the drug release profile and durability of the polymer-Ti interface. We found that a bi-layered nanofiber structure, produced by electrospinning of an inner layer of [PCL/Van] and an outer layer of [PLGA/Rif], yielded the optimal combinatorial drug release profile. This resulted in markedly enhanced bactericidal activity against planktonic and adherent Staphylococcus aureus for 6 weeks as compared to single drug delivery. Moreover, after 6 weeks, synergistic bacterial killing was observed as a result of sustained Van and Rif release. The application of a nanofiber-filled lattice structure successfully prevented the delamination of the multi-layer coating after press-fit cadaveric bone implantation. This new lattice design, in conjunction with the multi-layer nanofiber structure, can be applied to develop tunable and durable coatings for various metallic implantable devices. This is particularly appealing to tune the release of multiple antimicrobial agents over a period of weeks to prevent early and delayed onset IAI.

Physical, electrochemical and biological evaluations of spin-coated ε-polycaprolactone thin films containing alumina/graphene/carbonated hydroxyapatite/titania for tissue engineering applications

Composite structures are at the frontier of materials science and engineering and polymeric/ceramic composites present one of their most prospective subsets. Prior studies have shown both improvements and deteriorations of properties of polymers upon the addition of ceramic phases to them, but not many studies have dealt with the direct comparison of chemically distinct inorganic additives. The goal of this study was to compare the properties of ε-polycaprolactone (PCL) thin films supplemented with alumina, graphene, carbonated hydroxyapatite or titania particles, individually, in identical amounts (12 wt%). The composite films were analyzed for their phase composition, grain size, morphology, surface roughness, porosity, cell response, mechanical properties and electrochemical performance. Each additive imparted one or more physical or biological properties onto PCL better than others. Thus, alumina increased the microhardness of the films better than any other additive, with the resulting values exceeding 10 MPa. It also led to the formation of a composite with the least porosity and the greatest stability to degradation in simulated body fluid based on open circuit potential (OCP) measurements and electrochemical impedance spectroscopy (EIS). Titania made the surface of PCL roughest, which in combination with its high porosity explained why it was the most conducive to the growth of human fibroblasts, alongside being most prone to degradation in wet, corrosive environments and having the highest Poisson's ratio. Graphene, in contrast, made the surface of PCL smoothest and the bulk structure most porous, but also most conductive, with the OCP of -37 mV. The OCP of PCL supplemented with carbonated hydroxyapatite had the highest OCP of -134 mV and also the highest mechanical moduli, including the longitudinal (781 MPa), the shear (106 MPa), the bulk (639 MPa), and the elastic (300 MPa). The only benefit of the deposition of multilayered PCL films supplemented with all four inorganic additives was to enable a relatively high resistance to degradation. This study demonstrates that the properties of thin PCL films could be effectively optimized through the simple choice of appropriate inorganic additives dispersed in them. There is no single additive that proves ideal for improving all the properties of interest in PCL thin films, but their choice should be adjusted to the actual application. One such method of compositional optimization could prove crucial in the effort to develop biocomposites for superior performance in tissue engineering applications.

Materials for Orthopedic Bioimplants: Modulating Degradation and Surface Modification Using Integrated Nanomaterials

Significant research and development in the field of biomedical implants has evoked the scope to treat a broad range of orthopedic ailments that include fracture fixation, total bone replacement, joint arthrodesis, dental screws, and others. Importantly, the success of a bioimplant depends not only upon its bulk properties, but also on its surface properties that influence its interaction with the host tissue. Various approaches of surface modification such as coating of nanomaterial have been employed to enhance antibacterial activities of a bioimplant. The modified surface facilitates directed modulation of the host cellular behavior and grafting of cell-binding peptides, extracellular matrix (ECM) proteins, and growth factors to further improve host acceptance of a bioimplant. These strategies showed promising results in orthopedics, e.g., improved bone repair and regeneration. However, the choice of materials, especially considering their degradation behavior and surface properties, plays a key role in long-term reliability and performance of bioimplants. Metallic biomaterials have evolved largely in terms of their bulk and surface properties including nano-structuring with nanomaterials to meet the requirements of new generation orthopedic bioimplants. In this review, we have discussed metals and metal alloys commonly used for manufacturing different orthopedic bioimplants and the biotic as well as abiotic factors affecting the failure and degradation of those bioimplants. The review also highlights the currently available nanomaterial-based surface modification technologies to augment the function and performance of these metallic bioimplants in a clinical setting.

A novel pathway to produce biodegradable and bioactive PLGA/TiO2 nanocomposite scaffolds for tissue engineering: Air-liquid foaming

Poly (lactate-co-glycolate) (PLGA) is a typical biocompatible and biodegradable synthetic polymer. The addition of TiO₂ nanoparticles has shown to improve compressive modulus of PLGA scaffolds and reduced fast degradation. A novel method has been applied to fabricate PLGA/TiO₂ scaffolds without using any inorganic solvent, with aim of improving the biocompatibility, macroscale morphology, and well inter-connected pores efficacy: Air-Liquid Foaming. Field Emission Scanning Electron Microscopy (FESEM) revealed an increase in interconnected porosity of up to 98%. As well the compressive testing showed enhancement in modulus. Bioactivity and in vitro degradation were studied with immersion of scaffolds in Simulated Body Fluid (SBF) and incubation in Phosphate Buffered Saline (PBS), respectively. Formation of apatite layer corroborated the bioactivity after soaking in SBF. Degradation rate of scaffolds was increased with excessive addition of TiO₂ contents withal. The in vitro cultured human-like MG63 ostoblast cells showed attachment, proliferation, and nontoxcitiy in contact, using MTT assay [3-(4, 5-Dimethylthiazol-2-yl)-2, 5-Diphenyltetrazolium Bromide]. According to the results, the novel method utilized in this study generated porous viable tissue without using any inorganic solvent or porogen can be a promising candidate in further treatment of orthopedic patients effectively.

Biomimetic TiO2-chitosan/sodium alginate blended nanocomposite scaffolds for tissue engineering applications

The study is aimed to synthesize potent metal oxide based biomimetic nanocomposites to overcome the risk associated with artificial bone tissue engineering. High purity TiO₂ nanoparticles are synthesized via hydrothermal route. A biomimetic nanocomposite scaffolds containing chitosan-sodium alginate (4: 4) blended with three different (0.5, 1, and 1.5 wt%) concentrations of hydrothermally synthesized TiO₂ nanoparticles are obtained by solvent casting technique. The physico-chemical and thermal degradation properties of as-synthesized TiO₂ nanoparticles and their nanocomposite scaffolds are analyzed. In-vitro cytotoxicity and biocompatibility of the prepared TiO₂ nanoparticles and nanocomposites are tested against human bladder tumor (UC6) and osteosarcoma (MG-63) cell lines. Antibacterial property is tested against Escherichia coli and Staphylococcus aureus. These studies reveal that TiO₂ nanoparticles and polymeric nanocomposites contain good physico-chemical and mechanical properties for enhanced in-vitro biocompatibility suitable for biomedical applications. Biomimetically prepared chitosan-sodium alginate scaffold containing TiO₂ nanoparticles (1 wt%) is found to exhibit superior biocompatibility for bone tissue engineering applications.

Synthesis of Ag and TiO2 modified polycaprolactone electrospun nanofibers (PCL/TiO2-Ag NFs) as a multifunctional material for SERS, photocatalysis and antibacterial applications

In this study, we reported the design and the fabrication of Ag and TiO₂ modified polycaprolactone (PCL) electrospun nanofiber (NF) mats. The as-prepared NF mats were fabricated by one-step electrospinning and it was exploited for three different purposes (i) reusable SERS substrate for quantitative analysis to trace organic pollutants, (ii) photocatalyst for degradation of organic pollutants and (iii) antibacterial agent for killing of bacteria. Three different nanofiber mats, PCL, PCL-TiO₂, PCL/TiO₂-Ag NFs. were fabricated and further investigated. The morphologies and structures of the as-prepared nanofiber mats were carried out using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FT-IR) techniques. PCL/TiO₂-Ag NFs served as a highly effective SERS platform with a detection limit of 10 nM for the detection of methylene blue dye (MB). A remarkable feature of the presented platform is the ability to reuse the PCL/TiO₂-Ag NFs for SERS analysis of MB; availing from its capability for self-cleaning under UV light. By employing PCL/TiO₂-Ag NFs nanocatalyst, complete photocatalytic degradation of the probe analytes MB and ibuprofen (Ibu) under UV irradiation was accomplished not more than 180 min. Moreover, PCL/TiO₂-Ag NF mats showed a highly promising bactericidal feature against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria, which immensely emerged due to the presence of Ag NPs. This new trending nanofiber is assumed to lead a bunch of changes in the field of photocatalytic, SERS and antibacterial studies.

Development of nanofibrous scaffolds by varying the TiO2 content in crosslinked PVA for bone tissue engineering

Development of TiO₂ incorporated crosslinked PVA scaffolds with required characteristics for bone tissue engineering.

A Comprehensive Review on Bio-Nanomaterials for Medical Implants and Feasibility Studies on Fabrication of Such Implants by Additive Manufacturing Technique

Nanomaterials have allowed significant breakthroughs in bio-engineering and medical fields. In the present paper a holistic assessment on diverse biocompatible nanocomposites are studied. Their compatibility with advanced fabrication methods such as additive manufacturing for the design of functional medical implants is also critically reviewed. The significance of nanocomposites and processing techniques is also envisaged comprehensively in regard with the needs and futures of implantable medical device industries.

Antiseptic sealant and a nanocoated implant-abutment interface improve the results of dental implantation

BACKGROUND

Clinical measures and implant design innovation to improve primary osseointegration and reduce the bacterial contamination of the peri-implant area are intended to reduce the incidence of late inflammatory complications in dental implantation.

PURPOSE

To study the effect of nanostructured coating and antiseptic sealant on the outcomes of dental implantation.

MATERIALS AND METHODS

Ninety-six individuals were clinically supervised. In the first group (Screw Ti + sealant), a special antiseptic sealant matrix was used; the same sealant was used with nanocoated implants in the second group (Nanocoat + sealant), and the conventional treatment protocol was used in the control group (Screw Ti). Patients were evaluated longitudinally during treatment and rehabilitation phases with clinical examinations, radiography, periodontal pathogen detection, and patient experience surveys.

RESULTS

For patients who received a nanocoated implant and an antiseptic sealant (Nanocoat + sealant), relatively better hygienic indices were observed; there was less contamination with periodontal pathogens, bone density remained at the required level, and the overall results of treatment were better.

CONCLUSIONS

Using a matrix for sealing the dental implant-abutment interface with a nanostructured surface provides reliable results regarding stable osseointegration and clinical and patient-reported outcomes of treatment success.

Plasma-Coated Polycaprolactone Nanofibers with Covalently Bonded Platelet-Rich Plasma Enhance Adhesion and Growth of Human Fibroblasts

Biodegradable nanofibers are extensively employed in different areas of biology and medicine, particularly in tissue engineering. The electrospun polycaprolactone (PCL) nanofibers are attracting growing interest due to their good mechanical properties and a low-cost structure similar to the extracellular matrix. However, the unmodified PCL nanofibers exhibit an inert surface, hindering cell adhesion and negatively affecting their further fate. The employment of PCL nanofibrous scaffolds for wound healing requires a certain modification of the PCL surface. In this work, the morphology of PCL nanofibers is optimized by the careful tuning of electrospinning parameters. It is shown that the modification of the PCL nanofibers with the COOH plasma polymers and the subsequent binding of NH2 groups of protein molecules is a rather simple and technologically accessible procedure allowing the adhesion, early spreading, and growth of human fibroblasts to be boosted. The behavior of fibroblasts on the modified PCL surface was found to be very different when compared to the previously studied cultivation of mesenchymal stem cells on the PCL nanofibrous meshes. It is demonstrated by X-ray photoelectron spectroscopy (XPS) that the freeze-thawed platelet-rich plasma (PRP) immobilization can be performed via covalent and non-covalent bonding and that it does not affect biological activity. The covalently bound components of PRP considerably reduce the fibroblast apoptosis and increase the cell proliferation in comparison to the unmodified PCL nanofibers or the PCL nanofibers with non-covalent bonding of PRP. The reported research findings reveal the potential of PCL matrices for application in tissue engineering, while the plasma modification with COOH groups and their subsequent covalent binding with proteins expand this potential even further. The use of such matrices with covalently immobilized PRP for wound healing leads to prolonged biological activity of the immobilized molecules and protects these biomolecules from the aggressive media of the wound.

Preparation and Characterization of Poly(δ-Valerolactone)/TiO2 Nanohybrid Material with Pores Interconnected for Potential Use in Tissue Engineering

Titanium dioxide/poly(δ-valerolactone) (TiO₂/Pδ-VL) nanohybrid material containing interconnected pores with sizes in the range 80–150 μm were prepared by the solvent casting and polymer melting routes, and the dispersion of the TiO₂ nanofiller in the Pδ-VL matrix and its adhesion were characterized by X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy. A significant depression in the glass transition temperature (T_g) and melting temperature (T_m) values were revealed for the polymer nanocomposites prepared by the solvent casting technique. For the potential application of the prepared materials in the biomedical domain, complementary analyses were performed to examine the dynamic mechanical properties, and cell adhesion (using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay), and the results obtained for the samples prepared by the two methods were compared. Interconnected pores were successively produced in the new material by employing naphthalene microparticles as a porogen for the first time, and the results obtained were very promising.

Thermal Properties and Non-Isothermal Crystallization Kinetics of Poly (δ-Valerolactone) and Poly (δ-Valerolactone)/Titanium Dioxide Nanocomposites

New poly (δ-valerolactone)/titanium dioxide (PDVL/TiO2) nanocomposites with different TiO2 nanoparticle loadings were prepared by the solvent-casting method and characterized by Fourier transform infra-red, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy, and thermogravimetry analyses. The results obtained reveal good dispersion of TiO2 nanoparticles in the polymer matrix and non-formation of new crystalline structures indicating the stability of the crystallinity of TiO2 in the composite. A significant increase in the degree of crystallinity was observed with increasing TiO2 content. The non-isothermal crystallization kinetics of the PDVL/TiO2 system indicate that the crystallization process involves the simultaneous occurrence of two- and three-dimensional spherulitic growths. The thermal degradation analysis of this nanocomposite reveals a significant improvement in the thermal stability with increasing TiO2 loading.