Biological properties of polycaprolactone and barium titanate composite in biomedical applications

The ceramic-polymer composite materials are widely known for their exceptional mechanical and biological properties. Polycaprolactone (PCL) is a biodegradable polymer material extensively used in various biomedical applications. At the same time, barium titanate (BT), a ceramic material, exhibits piezoelectric properties similar to bone, which is essential for osseointegration. Furthermore, a composite material that combines the benefits of PCL and BT results in an innovative composite material with enhanced properties for biomedical applications. Thus, this review is organised into three sections. Firstly, it aims to provide an overview of the current research on evaluating biological properties, including antibacterial activity, cytotoxicity and osseointegration, of PCL polymeric matrices in its pure form and reinforced structures with ceramics, polymers and natural extracts. The second section investigates the biological properties of BT, both in its pure form and in combination with other supporting materials. Finally, the third section provides a summary of the biological properties of the PCLBT composite material. Furthermore, the existing challenges of PCL, BT and their composites, along with future research directions, have been presented. Therefore, this review will provide a state-of-the-art understanding of the biological properties of PCL and BT composites as potential futuristic materials in 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.

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Antibacterial, antifungal and antibiofilm scaffolds.

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Antimicrobial scaffold fabrication techniques.

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Antimicrobial biomaterials for tissue engineering applications.

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Antimicrobial characterization methods of scaffolds.

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Bone, oral tissue, skin, muscle, nerve, trachea, cardiac, among other applications.

Lactobacillus amylovorus derived lipase-mediated silver derivatization over poly(ε-caprolactone) towards antimicrobial coatings

Owing to the probiotic origin, lipases-derived from the Lactobacilli sp. are considered to be promising biomaterials for in vivo applications. On a different note, poly(ε-caprolactone) (PCL)-an FDA-approved polymer for implantable applications-lacks inherent antimicrobial property, because of which suitable modifications are required to render it with bactericidal activity. Here, we employ Lactobacillus amylovorous derived lipase to surface derivatize the PCL films with silver that is a highly efficient inorganic broad-spectrum antimicrobial substance. Two different surface functionalization strategies have been employed over the alkaline hydrolyzed PCL films towards this purpose: In the first strategy, lipase-capped silver nanoparticles (Ag NPs) have been synthesized in a first step, which have been covalently immobilized over the activated carboxylic groups on the PCL film surface in a subsequent step. In the second strategy, the lipase was covalently immobilized over the activated carboxylic groups of the PCL film surface in the first step, over which silver was deposited in the second step using the dip-coating method. While the characterization study using X-ray photoelectron spectroscopy (XPS) has revealed the successful derivatization of silver over the PCL film, the surface characterization using field-emission scanning electron microscopy (FE-SEM) study has shown a distinct morphological change with higher silver loading in both strategies. The antimicrobial studies employing E. coli have revealed 100 % inhibition in the bacterial growth in 4-6 h with the Ag NPs-immobilized PCL films as opposed to >8 h with those prepared through the dip-coating method. Additionally, the cytotoxicity assay using mouse fibroblast cells has shown that the PCL films immobilized with lipase-capped Ag NPs exhibit high cell compatibility, similar to that of pristine PCL film, and thereby making it suitable for in vivo applications.

Green Synthesis of Silver Nanoparticles Using Extract of Cilembu Sweet Potatoes (Ipomoea batatas L var. Rancing) as Potential Filler for 3D Printed Electroactive and Anti-Infection Scaffolds

Electroactive biomaterials are fascinating for tissue engineering applications because of their ability to deliver electrical stimulation directly to cells, tissue, and organs. One particularly attractive conductive filler for electroactive biomaterials is silver nanoparticles (AgNPs) because of their high conductivity, antibacterial activity, and ability to promote bone healing. However, production of AgNPs involves a toxic reducing agent which would inhibit biological scaffold performance. This work explores facile and green synthesis of AgNPs using extract of Cilembu sweet potato and studies the effect of baking and precursor concentrations (1, 10 and 100 mM) on AgNPs’ properties. Transmission electron microscope (TEM) results revealed that the smallest particle size of AgNPs (9.95 ± 3.69 nm) with nodular morphology was obtained by utilization of baked extract and ten mM AgNO₃. Polycaprolactone (PCL)/AgNPs scaffolds exhibited several enhancements compared to PCL scaffolds. Compressive strength was six times greater (3.88 ± 0.42 MPa), more hydrophilic (contact angle of 76.8 ± 1.7°), conductive (2.3 ± 0.5 × 10⁻³ S/cm) and exhibited anti-bacterial properties against Staphylococcus aureus ATCC3658 (99.5% reduction of surviving bacteria). Despite the promising results, further investigation on biological assessment is required to obtain comprehensive study of this scaffold. This green synthesis approach together with the use of 3D printing opens a new route to manufacture AgNPs-based electroactive with improved anti-bacterial properties without utilization of any toxic organic solvents.

Sputter-Deposited Ag Nanoparticles on Electrospun PCL Scaffolds: Morphology, Wettability and Antibacterial Activity

Porous scaffolds made of biocompatible and environmental-friendly polymer fibers with diameters in the nano/micro range can find applications in a wide variety of sectors, spanning from the biomedical field to textiles and so on. Their development has received a boost in the last decades thanks to advances in the production methods, such as the electrospinning technique. Conferring antimicrobial properties to these fibrous structures is a primary requirement for many of their applications, but the addition of antimicrobial agents by wet methods can present a series of drawbacks. In this work, strong antibacterial action is successfully provided to electrospun polycaprolactone (PCL) scaffolds by silver (Ag) addition through a simple and flexible way, namely the sputtering deposition of silver onto the PCL fibers. SEM-EDS analyses demonstrate that the polymer fibers get coated by Ag nanoparticles without undergoing any alteration of their morphological integrity upon the deposition process. The influence on wettability is evaluated with polar (water) and non-polar (diiodomethane) liquids, evidencing that this coating method allows preserving the hydrophobic character of the PCL polymer. Excellent antibacterial action (reduction > 99.995% in 4 h) is demonstrated against Escherichia coli. The easy fabrication of these PCL-Ag mats can be applicable to the production of biomedical devices, bioremediation and antifouling systems in filtration, personal protective equipment (PPE), food packaging materials, etc.

Bioengineering of Functional Nanosilver Nanogels for Smart Healthcare Systems

Functional designing of nanogels has become an attractive domain of biomedical engineering to develop bioactive materials with innovative features for the human healthcare system. Nanosilver has attracted enormous attention due to its wide antimicrobial spectrum and ability to kill almost all types of bacteria in its vicinity. However, the most crucial challenge for bioscientists is the lack of binding ability of nanosilver with the material surfaces that allow nanosilver to leach out to the surrounding tissue and exert toxicity while the biomaterial is in contact with the living system. Designing nanosilver within a nanogel confinement offers enormous possibilities to develop functional bioactive nanoparticles that may be bonded to any biomaterial surface via the nanogel functionality. This approach requires the proper combination of material science with nanotechnology and biotechnology to innovate interesting domain of functional nanogels with unique features. This work aims at providing a critical review on the current progress, approaches, and vision in designing nanosilver-entrapped nanogel particles with diverse functionality, and their bioactivity against microorganisms for human healthcare devices.