In Vitro Biocompatibility, Radiopacity, and Physical Property Tests of Nano-Fe₃O₄ Incorporated Poly-l-lactide Bone Screws

Biodegradable Conducting Polymer-Based Composites for Biomedical Applications-A Review

In recent years, researchers have increasingly directed their focus toward the biomedical field, driven by the goal of engineering polymer systems that possess a unique combination of both electrical conductivity and biodegradability. This convergence of properties holds significant promise, as it addresses a fundamental requirement for biomedical applications: compatibility with biological environments. These polymer systems are viewed as auspicious biomaterials, precisely because they meet this critical criterion. Beyond their biodegradability, these materials offer a range of advantageous characteristics. Their exceptional processability enables facile fabrication into various forms, and their chemical stability ensures reliability in diverse physiological conditions. Moreover, their low production costs make them economically viable options for large-scale applications. Notably, their intrinsic electrical conductivity further distinguishes them, opening up possibilities for applications that demand such functionality. As the focus of this review, a survey into the use of biodegradable conducting polymers in tissue engineering, biomedical implants, and antibacterial applications is conducted.

Magnetic and/or Radiopaque Functionalization of Self-Unfolding Foils for Improved Applicability within Oral Drug Delivery

Various types of microfabricated devices have been proposed for overcoming the gastrointestinal (GI) challenges associated with oral administration of pharmaceutical compounds. However, unidirectional drug release in very close forced proximity to the intestinal wall still appears to be an unresolved issue for many of these microdevices, which typically show low drug absorption and thereby low bioavailabilities. This work explores how recently developed and promising self-unfolding foils (SUFs) can be magnetically and/or radiopaquely (M/R-) functionalized, by the addition of BaSO4 or Fe3O4 nanoparticles, for improving their applicability within oral drug delivery. Through surface characterization, mechanical testing, and X-ray imaging, the (M/R-)SUFs are generally inspected and their overall properties compared. Furthermore, R-SUFs are being used in an in vivo rat X-ray imaging study, whereas in situ rat testing of MR-SUFs are attempted together with an investigation of their general magnetic properties. Unfolding of the R-SUF, and its very close forced proximity to the small intestine, is very easily observed 2 h post-administration by applying both computed tomography scanning and planar X-ray imaging. In addition, MR-SUFs show a great magnetic response in water, which suggests the possibility for controlled motion and retention in the GI tract. However, the magnetic response does not seem strong enough for in situ rat testing, but most likely a strong magnetization of the MR-SUFs using for example an impulse magnetizer can be made for increasing the magnetic response. All of the results presented herein are highly relevant and applicable for future usage of (M/R-)SUFs, as well as similar devices, in pre-clinical studies and potential clinical trials.

Compression Strength of PLA Bolts Produced via FDM

The aim of this research was to define the compression strength of polylactic acid bolts produced using the fused deposition modelling method. In accomplishing this, static and cyclic compression tests for different metric thread sizes were carried out in accordance with ISO 4014. Tests were conducted on M42, M48, M56, M60, and M64 threads, while samples with three different types of pitch-one nominal and two fine threads-were prepared for each diameter. Standard ISO 604 for defining the compression modulus Ec was implemented as the test basis. Accordingly, the mean compression modulus value Ec for all measurements was 917.79 ± 184.99 MPa. Cyclic compression tests were then carried out on samples with the M64 × 4 thread. Fifty thread loading cycles were carried out for each variant to obtained different strain amplitude values and strain frequencies. Our work indicated that the values of the storage modulus defined in cyclic tests E' increased, while the values of the loss modulus E″ decreased when the value of the strain frequency increased. We found it not possible to determine the nature of the changes in the value of the storage modulus E' in the function of the strain amplitude. We did, however, observe an increase in the value of the loss modulus E″, together with the increase in the tested range of the strain amplitude. The determined mechanical values can be therefore be used for designing threaded connections made of polylactic acid using the fused deposition modelling method.

ERp44 Regulates the Proliferation, Migration, Invasion, and Apoptosis of Gastric Cancer Cells Via Activation of ER Stress

Gastric cancer (GC) is one of the most prevalent malignancies worldwide. Endoplasmic reticulum (ER) stress plays a key role in the progression of GC. Rapid proliferation of tumor cells interferes with ER homeostasis, leading to ER stress and triggering unfolded protein response. Therefore, it is very necessary to investigate abnormally expressed ER resident proteins (ERp) in cancer cells. This study aimed to investigate the possible roles of ERp44. The mRNA and protein expression of genes were detected using qRT-PCR and western blot. Cell apoptosis was calculated using flow cytometry. Cell proliferation was determined using CCK-8 and colony formation assay. Cell migration was detected by wound healing, and cell invasion was measured by transwell assay. We found that ERp44 was obviously decreased in GC tissues. Furthermore, ERp44 overexpression distinctly suppressed the proliferation, migration, and invasion of MGC-803 and KATO III cells. In contrast, apoptosis was promoted by ERp44 overexpression. Furthermore, mechanistic studies revealed that overexpression of ERp44 inhibited malignant biological processes by regulating the eIF-2α/CHOP signaling pathway. Taken together, our data demonstrated that ERp44 regulated the proliferation, migration, invasion, and apoptosis via ERp44/eIF-2α/CHOP axis in GC. Targeting the ERp44and ER stress may be a promising strategy for GC.

Transcrystalline growth of PLLA on carbon fiber grafted with nano-SiO2 towards boosting interfacial bonding in bone scaffold

BACKGROUND

The reinforcement effect of fiber-reinforced polymer composites is usually limited because of the poor interfacial interaction between fiber and polymer, though fiber reinforcement is regarded as an effective method to enhance the mechanical properties of polymer.

METHODS

In this study, nano-SiO2 particles grafted by 3-Glycidoxypropyltrimethoxysilane (KH560) were introduced onto the surface of 3-Aminopropyltriethoxysilane (KH550) modified carbon fiber (CF) by a self-assembly strategy to improve the interfacial bonding between CF and biopolymer poly (lactic acid) (PLLA).

RESULTS

The results indicated that PLLA chains preferred to anchor at the surface of nano-SiO2 particles and then formed high order crystalline structures. Subsequently, PLLA spherulites could epitaxially grow on the surface of functionalized CF, forming a transcrystalline structure at the CF/PLLA interface. Meanwhile, the nano-SiO2 particles were fixed in the transcrystalline structure, which induced a stronger mechanical locking effect between CF and PLLA matrix. The results of tensile experiments indicated that the PLLA/CF-SiO2 scaffold with a ratio of CF to SiO2 of 9:3 possessed the optimal strength and modulus of 10.11 MPa and 1.18 GPa, respectively. In addition, in vitro tests including cell adhesion and fluorescence indicated that the scaffold had no toxicity and could provide a suitable microenvironment for the growth and proliferation of cell.

CONCLUSION

In short, the PLLA/CF-SiO2 scaffold with good mechanical properties and cytocompatibility had great potential in the application of bone tissue engineering.

Intrinsically radiopaque biomaterial assortments: a short review on the physical principles, X-ray imageability, and state-of-the-art developments

X-ray attenuation ability, otherwise known as radiopacity of a material, could be indisputably tagged as the central and decisive parameter that produces contrast in an X-ray image. Radiopaque biomaterials are vital in the healthcare sector that helps clinicians to track them unambiguously during pre and post interventional radiological procedures. Medical imaging is one of the most powerful resources in the diagnostic sector that aids improved treatment outcomes for patients. Intrinsically radiopaque biomaterials enable themselves for visual targeting/positioning as well as to monitor their fate and further provide the radiologists with critical insights about the surgical site. Moreover, the emergence of advanced real-time imaging modalities is a boon to the contemporary healthcare systems that allow to perform minimally invasive surgical procedures and thereby reduce the healthcare costs and minimize patient trauma. X-ray based imaging is one such technologically upgraded diagnostic tool with many variants like digital X-ray, computed tomography, digital subtraction angiography, and fluoroscopy. In light of these facts, this review is aimed to briefly consolidate the physical principles of X-ray attenuation by a radiopaque material, measurement of radiopacity, classification of radiopaque biomaterials, and their recent advanced applications.

Extrusion-Based 3D Printing Applications of PLA Composites: A Review

Polylactic acid (PLA) is the most widely used raw material in extrusion-based three-dimensional (3D) printing (fused deposition modeling, FDM approach) in many areas since it is biodegradable and environmentally friendly, however its utilization is limited due to some of its disadvantages such as mechanical weakness, water solubility rate, etc. FDM is a simple and more cost-effective fabrication process compared to other 3D printing techniques. Unfortunately, there are deficiencies of the FDM approach, such as mechanical weakness of the FDM parts compared to the parts produced by the conventional injection and compression molding methods. Preparation of PLA composites with suitable additives is the most useful technique to improve the properties of the 3D-printed PLA parts obtained by the FDM method. In the last decade, newly developed PLA composites find large usage areas both in academic and industrial circles. This review focuses on the chemistry and properties of pure PLA and also the preparation methods of the PLA composites which will be used as a raw material in 3D printers. The main drawbacks of the pure PLA filaments and the necessity for the preparation of PLA composites which will be employed in the FDM-based 3D printing applications is also discussed in the first part. The current methods to obtain PLA composites as raw materials to be used as filaments in the extrusion-based 3D printing are given in the second part. The applications of the novel PLA composites by utilizing the FDM-based 3D printing technology in the fields of biomedical, tissue engineering, human bone repair, antibacterial, bioprinting, electrical conductivity, electromagnetic, sensor, battery, automotive, aviation, four-dimensional (4D) printing, smart textile, environmental, and luminescence applications are presented and critically discussed in the third part of this review.

Physical and Biological Evaluation of Low-Molecular-Weight Hyaluronic Acid/Fe3O4 Nanoparticle for Targeting MCF7 Breast Cancer Cells

Low-molecular-weight hyaluronic acid (LMWHA) was integrated with superparamagnetic Fe₃O₄ nanoparticles (Fe₃O₄ NPs). The size distribution, zeta potential, viscosity, thermogravimetric and paramagnetic properties of the LMWHA-Fe₃O₄ NPs were systematically examined. For cellular experiments, MCF7 breast cancer cell line was carried out. In addition, the cell targeting ability and characteristics of the LMWHA-Fe₃O₄ NPs for MCF7 breast cancer cells were analyzed using the thiocyanate method and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The experimental results showed that the LMWHA-Fe₃O₄ NPs were not only easily injectable due to their low viscosity, but also exhibited a significant superparamagnetic property. Furthermore, the in vitro assay results showed that the NPs had negligible cytotoxicity and exhibited a good cancer cell targeting ability. Overall, the results therefore suggest that the LMWHA-Fe₃O₄ NPs have considerable potential as an injectable agent for enhanced magnetic resonance imaging (MRI) and/or hyperthermia treatment in breast cancer therapy.

Cerium- and Iron-Oxide-Based Nanozymes in Tissue Engineering and Regenerative Medicine

Nanoparticulate materials displaying enzyme-like properties, so-called nanozymes, are explored as substitutes for natural enzymes in several industrial, energy-related, and biomedical applications. Outstanding high stability, enhanced catalytic activities, low cost, and availability at industrial scale are some of the fascinating features of nanozymes. Furthermore, nanozymes can also be equipped with the unique attributes of nanomaterials such as magnetic or optical properties. Due to the impressive development of nanozymes during the last decade, their potential in the context of tissue engineering and regenerative medicine also started to be explored. To highlight the progress, in this review, we discuss the two most representative nanozymes, namely, cerium- and iron-oxide nanomaterials, since they are the most widely studied. Special focus is placed on their applications ranging from cardioprotection to therapeutic angiogenesis, bone tissue engineering, and wound healing. Finally, current challenges and future directions are discussed.

Synthesis and Characterization of Dental Nanocomposite Resins Filled with Different Clay Nanoparticles

Nanotechnology comprises a promising approach towards the update of dental materials.The present study focuses on the reinforcement ofdental nanocomposite resins with diverse organomodified montmorillonite (OMMT) nanofillers. The aim is to investigate whether the presence of functional groups in the chemical structure of the nanoclay organic modifier may virtually influence the physicochemical and/or the mechanical attitude of the dental resin nanocomposites. The structure and morphology of the prepared materials were investigated by means of wide angle X-ray diffraction and scanning electron microscopy analysis. Fourier transform infrared spectroscopy was used to determine the variation of the degree of conversion over time. Measurements of polymerization shrinkage and mechanical properties were conducted with a linear variable displacement transducer apparatus and a dynamometer, respectively. All the obtained nanocomposites revealed intercalated structures and most of them had an extensive filler distribution into the polymer matrix. Polymerization kinetics werefound to be influenced by the variance of the clay organomodifier, whilenanoclays with vinyl groups considerably increased the degree of conversion. Polymerization shrinkage was almost limited up to 50% by incorporating nanoclays. The absence of reactive groups in the OMMT structure may retain setting contraction atlow levels. An enhancement of the flexural modulus was observed, mainly by using clay nanoparticles decorated with methacrylated groups, along with a decrease in the flexural strength at a high filler loading. The overall best performance was found for the nanocomposites with OMMTs containing double bonds. The significance of the current work relies on providing novel information about chemical interactions phenomena between nanofillers and the organic matrix towards the improvement of dental restorative materials.

Synthesis, Characterization, and Visible Light Curing Capacity of Polycaprolactone Acrylate

Polycaprolactone (PCL) is drawing increasing attention in the field of medical 3D printing and tissue engineering because of its biodegradability. This study developed polycaprolactone prepolymers that can be cured using visible light. Three PCL acrylates were synthesized: polycaprolactone-530 diacrylate (PCL530DA), glycerol-3 caprolactone triacrylate (Glycerol-3CL-TA), and glycerol-6 caprolactone triacrylate (Glycerol-6CL-TA). PCL530DA has two acrylates, whereas Glycerol-3CL-TA and Glycerol-6CL-TA have three acrylates. The Fourier transform infrared and nuclear magnetic resonance spectra suggested successful synthesis of all PCL acrylates. All are liquid at room temperature and can be photopolymerized into a transparent solid after exposure to 470 nm blue LED light using 1% camphorquinone as photoinitiator and 2% dimethylaminoethyl methacrylate as coinitiator. The degree of conversion for all PCL acrylates can reach more than 80% after 1 min of curing. The compressive modulus of PCL530DA, Glycerol-3CL-TA, and Glycerol-6CL-TA is 65.7 ± 12.7, 80.9 ± 6.1, and 32.1 ± 4.1 MPa, respectively, and their compressive strength is 5.3 ± 0.29, 8.3 ± 0.18, and 3.0 ± 0.53 MPa, respectively. Thus, all PCL acrylates synthesized in this study can be photopolymerized and because of their solid structure and low viscosity, they are applicable to soft tissue engineering and medical 3D printing.