Structural and antibacterial studies of novel ZnO and ZnxMn(1-x)O nanostructured titanium scaffolds for biomedical applications

Recent Advances and Challenges for Biological Materials in Micro/Nanocarrier Synthesis for Bone Infection and Tissue Engineering

Roughly 1.71 billion people worldwide suffer from large bone abnormalities, which are the primary cause of disability. Traditional bone grafting procedures have several drawbacks that impair their therapeutic efficacy and restrict their use in clinical settings. A great deal of work has been done to create fresh, more potent strategies. Under these circumstances, a crucial technique for the regeneration of major lesions has emerged: bone tissue engineering (BTE). BTE involves the use of biomaterials that can imitate the natural design of bone. To yet, no biological material has been able to fully meet the parameters of the perfect implantable material, even though several varieties have been created and investigated for bone regeneration. Against this backdrop, researchers have focused a great deal of interest over the past few years on the subject of nanotechnology and the use of nanostructures in regenerative medicine. The ability to create nanoengineered particles that can overcome the current constraints in regenerative strategies─such as decreased cell proliferation and differentiation, insufficient mechanical strength in biological materials, and insufficient production of extrinsic factors required for effective osteogenesis has revolutionized the field of bone and tissue engineering. The effects of nanoparticles on cell characteristics and the application of biological materials for bone regeneration are the main topics of our review, which summarizes the most recent in vitro and in vivo research on the application of nanotechnology in the context of BTE.

First Vibrational Fingerprint of Parietaria judaica Protein via Surface-Enhanced Raman Spectroscopy

Accurate identification and characterization of allergenic proteins at the molecular level are essential for pinpointing the specific protein structures responsible for allergic reactions, thus advancing the development of precise diagnostic tests. Significant efforts have been focused on novel experimental techniques aimed at deepening the understanding of the underlying molecular mechanisms of these reactions. In this work, we show, for the first time to our knowledge, the unique Raman fingerprint of three Parietaria judaica (Par j) allergenic proteins. These proteins are typically present in pollen and are known to trigger severe respiratory diseases. In our research, we further exploited the surface-enhanced Raman scattering (SERS) effect from an Ag dendrite substrate. This approach provided better discrimination and a comprehensive analysis of the proteins Par j 1, 2, and 4 in hydration conditions, enabling rapid differentiation between them through a spectroscopic study.

Corrosion behavior, antibacterial properties and in vitro and in vivo biocompatibility of biodegradable Zn-5Cu-xMg alloy for bone-implant applications

Reasonable optimization of degradation rate, antibacterial performance and biocompatibility is crucial for the development of biodegradable zinc alloy medical implant devices with antibacterial properties. In this study, various amounts of Mg elements were incorporated into Zn5Cu alloy to modulate the degradation rate, antibacterial properties and biocompatibility. The effects of Mg contents on the microstructure, corrosion behavior, antibacterial properties and biocompatibility of Zn-5Cu-xMg alloy were extensively investigated. The results revealed that with an increase of Mg content, the amount of Mg2Zn11 phase increased and its galvanic effect with the Zn matrix was enhanced, which accelerated the corrosion process and led to higher corrosion rate and high degradation rate of the alloy. Additionally, there was an increased release of Mg2+ and Zn2+ ions from the alloy which imparted excellent resistance against Escherichia coli and Staphylococcus aureus bacteria and improved biocompatibility, subcutaneous antibacterial and immune microenvironment regulation properties. Zn-5Cu-2 Mg exhibited superior antibacterial ability, cell compatibility, proliferation effect, subcutaneous antibacterial and immune microenvironment regulation performances, which can work as a promising candidate of biodegradable antibacterial medical implants.

The Mechanism of Zinc Oxide in Alleviating Diarrhea in Piglets after Weaning: A Review from the Perspective of Intestinal Barrier Function

Weaning is one of the most challenging phases for piglets, and it is also the time when piglets are the most susceptible to diarrhea, which may result in significant economic losses for pig production. One of the dietary strategies for reducing post-weaning diarrhea (PWD) in piglets is to provide them with a pharmacological dose of zinc oxide (ZnO). However, excessive or long-term usage of high-dose ZnO has significant impacts on pig health and the ecological environment. Therefore, caution should be exercised when considering the use of high-dose ZnO for the prevention or treatment of PWD in piglets. In this paper, the significant role of zinc in animal health, the potential mode of action of ZnO in alleviating diarrhea, and the impact of innovative, highly efficient ZnO alternatives on the regulation of piglet diarrhea were reviewed to offer insights into the application of novel ZnO in pig production.

Bone Tissue Engineering and Nanotechnology: A Promising Combination for Bone Regeneration

Large bone defects are the leading contributor to disability worldwide, affecting approximately 1.71 billion people. Conventional bone graft treatments show several disadvantages that negatively impact their therapeutic outcomes and limit their clinical practice. Therefore, much effort has been made to devise new and more effective approaches. In this context, bone tissue engineering (BTE), involving the use of biomaterials which are able to mimic the natural architecture of bone, has emerged as a key strategy for the regeneration of large defects. However, although different types of biomaterials for bone regeneration have been developed and investigated, to date, none of them has been able to completely fulfill the requirements of an ideal implantable material. In this context, in recent years, the field of nanotechnology and the application of nanomaterials to regenerative medicine have gained significant attention from researchers. Nanotechnology has revolutionized the BTE field due to the possibility of generating nanoengineered particles that are able to overcome the current limitations in regenerative strategies, including reduced cell proliferation and differentiation, the inadequate mechanical strength of biomaterials, and poor production of extrinsic factors which are necessary for efficient osteogenesis. In this review, we report on the latest in vitro and in vivo studies on the impact of nanotechnology in the field of BTE, focusing on the effects of nanoparticles on the properties of cells and the use of biomaterials for bone regeneration.

Anti-Biofilm Strategies: A Focused Review on Innovative Approaches

Biofilm (BF) can give rise to systemic infections, prolonged hospitalization times, and, in the worst case, death. This review aims to provide an overview of recent strategies for the prevention and destruction of pathogenic BFs. First, the main phases of the life cycle of BF and maturation will be described to identify potential targets for anti-BF approaches. Then, an approach acting on bacterial adhesion, quorum sensing (QS), and the extracellular polymeric substance (EPS) matrix will be introduced and discussed. Finally, bacteriophage-mediated strategies will be presented as innovative approaches against BF inhibition/destruction.

Multifunctional polydopamine - Zn2+-curcumin coated additively manufactured ceramic bone grafts with enhanced biological properties

The lack of site-specific chemotherapeutic agents after osteosarcoma surgeries often induces severe side effects. We propose the utilization of curcumin as an alternative natural chemo-preventive drug for tumor-specific delivery systems with 3D printed tricalcium phosphate (TCP) based artificial bone grafts. The poor bioavailability and hydrophobic nature of curcumin restrict its clinical use. We have used polydopamine (PDA) coating with Zn2+ functionalization to enhance the curcumin release in the biological medium. The obtained PDA-Zn2+ complex is characterized by X-ray photoelectron spectroscopy (XPS). The presence of PDA-Zn2+ coating leads to ~2 times enhancement in curcumin release. We have computationally predicted and validated the optimized surface composition by a novel multi-objective optimization method. The experimental validation of the predicted compositions indicates that the PDA-Zn2+ coated curcumin immobilized delivery system leads to a ~12 folds decrease in osteosarcoma viability on day 11 as compared to only TCP. The osteoblast viability shows ~1.4 folds enhancement. The designed surface shows the highest ~90 % antibacterial efficacy against gram-positive and gram-negative bacteria. This unique strategy of curcumin delivery with PDA-Zn2+ coating is expected to find application in low-load bearing critical-sized tumor-resection sites.

Surface Photovoltage Response of ZnO to Phosphate-Buffered Saline Solution with and without Presence of Staphylococcus aureus

Nano- and microscale zinc oxide (ZnO) exhibits significant potential as a novel antibacterial agent in biomedical applications. However, the uncertainty regarding the underlying mechanisms of the observed antimicrobial action inhibits the realization of this potential. Particularly, the nature of interactions at the free crystalline surface and the influence of the local bacterial environment remains unclear. In this investigation, we utilize ZnO particles synthesized via tunable hydrothermal growth method as a platform to elucidate the effects of interactions with phosphate-rich environments and differentiate them from those with bacteria. This is achieved using the time- and energy-dependent surface photovoltage (SPV) to monitor modifications of the surface electronic structure and surface charge dynamics of the ZnO particles due to these interactions. It is found that there exists a dramatic change in the SPV transients after exposure to phosphate-rich environments. It also presents differences in the sub-bandgap surface electronic structure after these exposures. It can be suggested that these phenomena are a consequence of phosphate adsorption at surface traps corresponding to zinc deficiency defects. This effect is shown to be suppressed in the presence of Staphylococcus aureus bacteria. Our results support the previously proposed model of the competitive nature of interactions between S. aureus and aqueous phosphates with the free surface of ZnO and bring greater clarity to the effects of phosphate-rich environments on bacterial growth inhibition of ZnO.

Biological Response Evaluation of Human Fetal Osteoblast Cells and Bacterial Cells on Fractal Silver Dendrites for Bone Tissue Engineering

Prosthetic joint replacement is the most widely used surgical approach to repair large bone defects, although it is often associated with prosthetic joint infection (PJI), caused by biofilm formation. To solve the PJI problem, various approaches have been proposed, including the coating of implantable devices with nanomaterials that exhibit antibacterial activity. Among these, silver nanoparticles (AgNPs) are the most used for biomedical applications, even though their use has been limited by their cytotoxicity. Therefore, several studies have been performed to evaluate the most appropriate AgNPs concentration, size, and shape to avoid cytotoxic effects. Great attention has been focused on Ag nanodendrites, due to their interesting chemical, optical, and biological properties. In this study, we evaluated the biological response of human fetal osteoblastic cells (hFOB) and P. aeruginosa and S. aureus bacteria on fractal silver dendrite substrates produced by silicon-based technology (Si_Ag). In vitro results indicated that hFOB cells cultured for 72 h on the Si_Ag surface display a good cytocompatibility. Investigations using both Gram-positive (S. aureus) and Gram-negative (P. aeruginosa) bacterial strains incubated on Si_Ag for 24 h show a significant decrease in pathogen viability, more evident for P. aeruginosa than for S. aureus. These findings taken together suggest that fractal silver dendrite could represent an eligible nanomaterial for the coating of implantable medical devices.

Physiologic Response Evaluation of Human Foetal Osteoblast Cells within Engineered 3D-Printed Polylactic Acid Scaffolds

Large bone defect treatments have always been one of the important challenges in clinical practice and created a huge demand for more efficacious regenerative approaches. The bone tissue engineering (BTE) approach offered a new alternative to conventional bone grafts, addressing all clinical needs. Over the past years, BTE research is focused on the study and realisation of new biomaterials, including 3D-printed supports to improve mechanical, structural and biological properties. Among these, polylactic acid (PLA) scaffolds have been considered the most promising biomaterials due to their good biocompatibility, non-toxic biodegradability and bioresorbability. In this work, we evaluated the physiological response of human foetal osteoblast cells (hFOB), in terms of cell proliferation and osteogenic differentiation, within oxygen plasma treated 3D-printed PLA scaffolds, obtained by fused deposition modelling (FDM). A mechanical simulation to predict their behaviour to traction, flexural or torque solicitations was performed. We found that: 1. hFOB cells adhere and grow on scaffold surfaces; 2. hFOB grown on oxygen plasma treated PLA scaffolds (PLA_PT) show an improvement of cell adhesion and proliferation, compared to not-plasma treated scaffolds (PLA_NT); 3. Over time, hFOB penetrate along strands, differentiate, and form a fibrous matrix, tissue-like; 4. 3D-printed PLA scaffolds have good mechanical behaviour in each analysed configuration. These findings suggest that 3D-printed PLA scaffolds could represent promising biomaterials for medical implantable devices in the orthopaedic field.