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Introduction: Post-processing (PP) is performed to improve the surface, which can favor microbial adhesion and consequent pathological manifestations that impair the indication of polylactic acid (PLA) obtained by fused filament fabrication (FFF) for biomedical applications. This aims to evaluate the influence of chemical, thermal, and mechanical PP on the adhesion of Streptococcus mutants and Candida albicans, roughness, and wettability of the PLA obtained by FFF with and without thermal aging. Methods: The specimens were designed in the 3D modeling program and printed. The chemical PP was performed by immersion in chloroform, the thermal by the annealing method, and the mechanical by polishing. Thermal aging was performed by alternating the temperature from 5 °C to 55 °C with 5000 cycles. Colony-forming unit (CFU/mL) counting was performed on dual-species biofilm of C. albicans and S. mutans. Roughness was analyzed by rugosimeter and wettability by the sessile drop technique. Data were verified for normality using the Shapiro-Wilk test, two-way ANOVA (α = 0.05) applied for CFU and wettability, and Kruskal-Wallis (α = 0.05) for roughness. Results: Chemical, thermal, and mechanical PP methods showed no influence on CFU/mL of C. albicans (p = 0.296) and S. mutans (p = 0.055). Thermal aging did not influence microbial adhesion. Chemical PP had lower roughness, which had increased after aging. Wettability of the mechanical PP was lower. Conclusions: Post-processing techniques, do not present an influence on the adhesion of S. mutans and C. albicans in PLA obtained by FFF, chemical PP reduced roughness, and mechanical reduced wettability. Thermal aging did not alter the microbial adhesion and altered the roughness and wettability.

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The dip coating process is one of the recognized techniques used to generate polymeric coatings on stents in an easy and low-cost way. However, there is a lack of information about the influence of the process parameters of this technique on complex geometries such as stents. This paper studies the dip coating process parameters used to provide a uniform coating of PLA with a 4-10 µm thickness. A stainless-steel tube (AISI 316L) was laser-cut, electropolished, and dip-coated in a polylactic acid (PLA) solution whilst changing the process parameters. The samples were characterized to examine the coating's uniformity, thickness, surface roughness, weight, and chemical composition. FTIR and Raman investigations indicated the presence of PLA on the stent's surface, the chemical stability of PLA during the coating process, and the absence of residual chloroform in the coatings. Additionally, the water contact angle was measured to determine the hydrophilicity of the coating. Our results indicate that, when using entry and withdrawal speeds of 500 mm min-1 and a 15 s immersion time, a uniform coating thickness was achieved throughout the tube and in the stent with an average thickness of 7.8 µm.

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Background: B cells are pivotal in systemic lupus erythematosus and autoimmune disease pathogenesis. Materials & methods: To address this, Nile Red-labeled polylactic acid nanoparticles (NR-PLA NPs) loaded with the JAK inhibitor baricitinib (BARI), specifically targeting JAK1 and JAK2 in B cells, were developed. Results: Physicochemical characterization confirmed NP stability over 30 days. NR-PLA NPs were selectively bound and internalized by CD19+ B cells, sparing other leukocytes. In contrast to NR-PLA NPs, BARI-NR-PLA NPs significantly dampened B-cell activation, proliferation and plasma cell differentiation in healthy controls. They also inhibited key cytokine production. These effects often surpassed those of equimolar-free BARI. Conclusion: This study underscores the potential of PLA NPs to regulate autoreactive B cells, offering a novel therapeutic avenue for autoimmune diseases.

In this study, a new approach to treating autoimmune diseases, particularly systemic lupus erythematosus, was investigated by focusing on a type of immune cell called B cells. Special nanoparticles (NPs) labeled with Nile Red (NR) and made from polylactic acid (PLA) were created. These NPs were loaded with a drug called baricitinib (BARI), which targets specific proteins (JAK1 and JAK2) in B cells. This was done to determine if these NPs could help control the behavior of B cells, which are important in autoimmune diseases. First, these NPs remained stable for a long time (30 days). The NR-labeled PLA NPs (NR-PLA NPs) were also good at attaching to and entering a specific type of B cell called CD19⁺ B cells while leaving other types of immune cells alone. The use of NR-PLA NPs loaded with BARI produced exciting results. These NPs were better at reducing the activity, growth and transformation of B cells into plasma cells compared with the drug BARI by itself. They also stopped the production of certain immune system signals called cytokines, which are usually overactive in autoimmune diseases. This work suggests that PLA NPs could be a promising way to control overactive B cells that contribute to autoimmune diseases like systemic lupus erythematosus. This could open a new and exciting path for developing treatments for these conditions.

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We explored the potential of different nanoparticles (TiO2, CaCO3, and Al2O3), considering their pure form and modified with cinnamon essential oil (CEO). These materials were characterized using various techniques, including FTIR spectroscopy, XRD analysis, TGA, and SEM. The interaction between CEO and nanoparticles changed depending on the nanoparticle type. Al2O3 nanoparticles exhibited the strongest interaction with CEO, increasing their antioxidant capacity by around 40% and their transfer of antimicrobial properties, particularly against Gram-negative bacteria. In contrast, TiO2 and CaCO3 nanoparticles showed limited interaction with CEO, resulting in lower antioxidant capacity and antimicrobial activity. Incorporating pure and CEO-modified nanoparticles into polylactic acid (PLA) films improved their mechanical and thermal properties, which are suitable for applications requiring greater strength. This research highlights the potential of metal oxide nanoparticles to enhance the antimicrobial and antioxidant capabilities of polymers. In addition, incorporating cinnamon essential oil can increase the antioxidant and antimicrobial effectiveness of the metal oxide nanoparticles and improve the mechanical and thermal properties of PLA films. Thus, these PLA films exhibit favorable characteristics for active packaging applications.

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Growing concerns about environmental issues and global warming have garnered increased attention in recent decades. Consequently, the use of materials sourced from renewable and biodegradable origins, produced sustainably, has piqued the interest of scientific researchers. Biodegradable and naturally derived polymers, such as cellulose and polylactic acid (PLA), have consistently been the focus of scientific investigation. The objective is to develop novel materials that could potentially replace conventional petroleum-based polymers, offering specific properties tailored for diverse applications while upholding principles of sustainability and technology as well as economic viability. Against this backdrop, the aim of this review is to provide a comprehensive overview of recent advancements in research concerning the use of polylactic acid (PLA) and the incorporation of cellulose as a reinforcing agent within this polymeric matrix, alongside the application of 3D printing technology. Additionally, a pivotal additive in the combination of PLA and cellulose, polyethylene glycol (PEG), is explored. A systematic review of the existing literature related to the combination of these materials (PLA, cellulose, and PEG) and 3D printing was conducted using the Web of Science and Scopus databases. The outcomes of this search are presented through a comparative analysis of diverse studies, encompassing aspects such as the scale and cellulose amount added into the PLA matrix, modifications applied to cellulose surfaces, the incorporation of additives or compatibilizing agents, variations in molecular weight and in the quantity of PEG introduced into the PLA/cellulose (nano)composites, and the resulting impact of these variables on the properties of these materials.

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To successfully implement additive manufacturing (AM) techniques for custom medical device (MD) production with low-cost resources, it is imperative to understand the effect of common and affordable sterilization processes, such as formaldehyde or steam sterilization, on pieces manufactured by AM. In this way, the performance of low-risk MDs, such as biomodels and surgical guides, could be assessed for complying with safety, precision, and MD delivery requirements. In this context, the aim of the present work was to evaluate the effect of formaldehyde and steam sterilization on the dimensional and mechanical stability of standard polylactic acid (PLA) test pieces produced by fused deposition modeling (FDM). To achieve this, PLA samples were sterilized according to the sterilization protocol of a public hospital in the city of Bucaramanga, Colombia. Significant changes regarding mechanical and dimensional properties were found as a function of manufacturing parameters. This research attempts to contribute to the development of affordable approaches for the fabrication of functional and customized medical devices through AM technologies, an issue of particular interest for low- and middle-income countries.

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This work investigated the addition of spent coffee grounds (SCG) as a valuable resource to produce biocomposites based on polylactic acid (PLA). PLA has a positive biodegradation effect but generates poor proprieties, depending on its molecular structure. The PLA and SCG (0, 10, 20 and 30 wt.%) were mixed via twin-screw extrusion and molded by compression to determine the effect of composition on several properties, including mechanical (impact strength), physical (density and porosity), thermal (crystallinity and transition temperature) and rheological (melt and solid state). The PLA crystallinity was found to increase after processing and filler addition (34-70% in the 1st heating) due to a heterogeneous nucleation effect, leading to composites with lower glass transition temperature (1-3 °C) and higher stiffness (~15%). Moreover, the composites had lower density (1.29, 1.24 and 1.16 g/cm3) and toughness (30.2, 26.8 and 19.2 J/m) as the filler content increased, which is associated with the presence of rigid particles and residual extractives from SCG. In the melt state, polymeric chain mobility was enhanced, and composites with a higher filler content became less viscous. Overall, the composite with 20 wt.% SCG provided the most balanced properties being similar to or better than neat PLA but at a lower cost. This composite could be applied not only to replace conventional PLA products, such as packaging and 3D printing, but also to other applications requiring lower density and higher stiffness.

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Throughout the entire coronavirus disease 19 (COVID-19) pandemic, there were disruptions in the supply chain of test materials around the world, primarily in poor- and middle-income countries. The use of 3D prints is an alternative to address swab supply shortages. In this study, the feasibility of the clinical use of 3D-printed swabs for oropharyngeal and nasopharyngeal sampling for the detection of SARS-CoV-2 infection was evaluated. For that purpose, paired samples with the 3D printed and the control swabs were taken from 42 adult patients and 10 pediatric patients, and the results obtained in the detection of SARS-CoV-2 by reverse transcription and quantitative polymerase chain reaction (RT-qPCR) were compared. Additionally, in those cases where the result was positive for SARS-CoV-2, the viral load was calculated by means of a mathematical algorithm proposed by us. For both adults and children, satisfactory results were obtained in the detection of SARS-CoV-2 by RT-qPCR; no significant differences were found in the quantification cycle values between the 3D-printed swab samples and the control samples. Furthermore, we corroborated that the 3D-printed swabs caused less discomfort and pain at the time of sampling. In conclusion, this study shows the feasibility of routinely using 3D-printed swabs for both adults and children. In this way, it is possible to maintain local and cheaper consumption along with fewer distribution difficulties.

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This study focused on the quality loss inhibition of fish muscle during refrigerated storage. Two parallel experiments were carried out that were focused on the employment of pitaya (Stenocereus thurberi) extracts in biodegradable packing films. On the one hand, a pitaya-gelatin film was employed for hake (Merluccius merluccius) muscle storage. On the other hand, a pitaya-polylactic acid (PLA) film was used for Atlantic mackerel (Scomber scombrus) muscle storage. In both experiments, fish-packing systems were stored at 4 °C for 8 days. Quality loss was determined by lipid damage and microbial activity development. The presence of the pitaya extract led to an inhibitory effect (p < 0.05) on peroxide, fluorescent compound, and free fatty acid (FFA) values in the gelatin-hake system and to a lower (p < 0.05) formation of thiobarbituric acid reactive substances, fluorescent compounds, and FFAs in the PLA-mackerel system. Additionally, the inclusion of pitaya extracts in the packing films slowed down (p < 0.05) the growth of aerobes, anaerobes, psychrotrophs, and proteolytic bacteria in the case of the pitaya-gelatin films and of aerobes, anaerobes, and proteolytic bacteria in the case of pitaya-PLA films. The current preservative effects are explained on the basis of the preservative compound presence (betalains and phenolic compounds) in the pitaya extracts.

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Polymeric nanocapsules (NC) are versatile mixed vesicular nanocarriers, generally containing a lipid core with a polymeric wall. They have been first developed over four decades ago with outstanding applicability in the cosmetic and pharmaceutical fields. Biodegradable polyesters are frequently used in nanocapsule preparation and among them, polylactic acid (PLA) derivatives and copolymers, such as PLGA and amphiphilic block copolymers, are widely used and considered safe for different administration routes. PLA functionalization strategies have been developed to obtain more versatile polymers and to allow the conjugation with bioactive ligands for cell-targeted NC. This review intends to provide steps in the evolution of NC since its first report and the recent literature on PLA-based NC applications. PLA-based polymer synthesis and surface modifications are included, as well as the use of NC as a novel tool for combined treatment, diagnostics, and imaging in one delivery system. Furthermore, the use of NC to carry therapeutic and/or imaging agents for different diseases, mainly cancer, inflammation, and infections is presented and reviewed. Constraints that impair translation to the clinic are discussed to provide safe and reproducible PLA-based nanocapsules on the market. We reviewed the entire period in the literature where the term "nanocapsules" appears for the first time until the present day, selecting original scientific publications and the most relevant patent literature related to PLA-based NC. We presented to readers a historical overview of these Sui generis nanostructures.

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The development of nanoscale biomaterials associated with polymers has been growing over the years, due to their important structural characteristics for applications in biological systems. The present study aimed to produce and test polymeric scaffolds composed of polylactic acid (PLA) fibers associated with a 58S bioglass doped with therapeutic ions for use in tissue engineering. Three 58S Bioglass was obtained by the sol-gel route, pure and doped with 5% strontium and cobalt ions. Solutions of 7% PLA was used as control and added the three different bioglass, 4% of 58S bioglass (PLA-BG), 4% bioglass-doped strontium (PLA-BGSr) and 4% bioglass-doped cobalt (PLA-BGCo). Scaffolds were produced through electrospinning process, and was characterized chemical and morphologically. The in vitro tests were performed using mesenchymal cells cultures from femurs of nine rats, grown in osteogenic supplemented total culture medium. After osteoblastic differentiation induction cell viability, alkaline phosphatase activity, total protein content quantification, and visualization of mineralization nodule tests were performed. Analysis of normal distribution used the Shapiro-Wilk test (nanofibers diameter and biological assay). Data were compared using the Kruskal-Wallis nonparametric test (p = 0.05). The bioglasses produced proved to be free of nitrate, chlorinated and nano-sized, with effective incorporation of therapeutic ions in their structure. All materials showed cell viability (>70%), total protein production, and alkaline phosphatase activity. It was possible to develop polylactic acid scaffolds associated with 58S bioglass doped with therapeutic ions without cytotoxicity. Scaffolds characteristics appear to sustain its application in bone tissue engineering.

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In this pilot study, we characterize and evaluate 3D-printed swabs for the collection of nasopharyngeal and oropharyngeal secretion samples for the SARS-CoV-2 detection. Swabs are made with the fused deposition modeling technique using the biopolymer polylactic acid (PLA) which is a medical-grade, biodegradable and low-cost material. We evaluated six swabs with mechanical tests in a laboratory and in an Adult Human Simulator performed by healthcare professionals. We proved the adequacy of the PLA swab to be used in the gold standard reverse transcriptase-polymerase chain reaction (qRT-PCR) for viral RNA detection. Then, we did in vitro validation for cell collection using the 3D-printed swabs and RNA extraction for samples from 10 healthy volunteers. The 3D-printed swabs showed good flexibility and maneuverability for sampling and at the same time robustness to pass into the posterior nasopharynx. The PLA did not interfere with the RNA extraction process and qRT-PCR test. When we evaluated the expression of the reference gene (RNase P) used in the SARS-CoV-2 detection, the 3D-printed swabs showed good reproducibility in the threshold cycle values (Ct = 23.5, range 19-26) that is comparable to control swabs (Ct = 24.7, range 20.8-32.6) with p value = 0.47. The 3D-printed swabs demonstrated to be a reliable, and an economical alternative for mass use in the detection of SARS-CoV-2.

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Natural fiber-reinforced composite (NFRC) filaments for 3D printing were fabricated using polylactic acid (PLA) reinforced with 1-5 wt% henequen flour comprising particles with sizes between 90-250 µm. The flour was obtained from natural henequen fibers. NFRCs and pristine PLA specimens were printed with a 0° raster angle for tension tests. The results showed that the NFRCs' measured density, porosity, and degree of crystallinity increased with flour content. The tensile tests showed that the NFRC Young's modulus was lower than that of the printed pristine PLA. For 1 wt% flour content, the NFRCs' maximum stress and strain to failure were higher than those of the printed PLA, which was attributed to the henequen fibers acting as reinforcement and delaying crack growth. However, for 2 wt% and higher flour contents, the NFRCs' maximum stress was lower than that of the printed PLA. Microscopic characterization after testing showed an increase in voids and defects, with the increase in flour content attributed to particle agglomeration. For 1 wt% flour content, the NFRCs were also printed with raster angles of ±45° and 90° for comparison; the highest tensile properties were obtained with a 0° raster angle. Finally, adding 3 wt% content of maleic anhydride to the NFRC with 1 wt% flour content slightly increased the maximum stress. The results presented herein warrant further research to fully understand the mechanical properties of printed NFRCs made of PLA reinforced with natural henequen fibers.

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Background: Conventional periodontal therapy relies on bone regeneration strategies utilizing scaffolds made of diverse materials, among which collagen, to promote cell adhesion and growth. Objective: To evaluate periodontal ligament fibroblast (HPdLF) cell adhesion and viability for periodontal regeneration purposes on hydroxyapatite scaffolds containing collagen (HAp-egg shell) combined with polylactic acid−polyglycolic acid copolymer (PLGA) and Platelet-Rich Fibrin (PRF). Methods: Four variations of the HAp-egg shell were used to seed HPdLF for 24 h and evaluate cell viability through a live/dead assay: (1) (HAp-egg shell/PLGA), (2) (HAp-egg shell/PLGA + collagen), (3) (HAp-egg shell/PLGA + PRF) and (4) (HAp-egg shell/PLGA + PRF + collagen). Cell adhesion and viability were determined using confocal microscopy and quantified using central tendency and dispersion measurements; significant differences were determined using ANOVA (p < 0.05). Results: Group 1 presented low cell viability and adhesion (3.70−10.17%); groups 2 and 3 presented high cell viability and low cell adhesion (group 2, 59.2−11.1%, group 3, 58−4.6%); group 4 presented the highest cell viability (82.8%) and moderate cell adhesion (45%) (p = 0.474). Conclusions: The effect of collagen on the HAp-egg shell/PLGA scaffold combined with PRF favored HPdLF cell adhesion and viability and could clinically have a positive effect on bone defect resolution and the regeneration of periodontal ligament tissue.

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The limitations associated with the clinical use of autographs and allografts are driving efforts to develop relevant and applicable biomaterial substitutes. In this research, 3D porous scaffolds composed of bioactive glass (BG) obtained through the sol-gel technique and polylactic acid (PLA) synthesized via lactic acid (LA) ring-opening polymerization were prepared by the gel-pressing technique. Two different weight compositions were evaluated, namely, BG70-PLA30 and BG30-PLA70. The structure and morphology of the resulting scaffolds were analysed by FTIR, XRD, SEM, and under ASTM F1635 standard characterizations. The results confirmed that BG promotes the formation of a hydroxy-carbonated apatite (HAp) layer on composites when immersed in simulated body fluid (SBF). Biodegradability evaluations were carried out according to the ISO 10993-13:2010 standard. In addition, electrochemical evaluations were performed in both Hank's and SBF solutions at 37 °C in order to analyse the degradation of the material. This evaluation allowed us to observe that both samples showed an activation mechanism in the early stages followed by pseudo-passivation due to physical bioactive glass characteristics, suggesting an improvement in the formation of the HAp nucleation. The described composites showed excellent resistance to degradation and outstanding suitability for bone tissue engineering applications.

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Scaffolds based on biopolymers and nanomaterials with appropriate mechanical properties and high biocompatibility are desirable in tissue engineering. Therefore, polylactic acid (PLA) nanocomposites were prepared with ceramic nanobioglass (PLA/n-BGs) at 5 and 10 wt.%. Bioglass nanoparticles (n-BGs) were prepared using a sol-gel methodology with a size of ca. 24.87 ± 6.26 nm. In addition, they showed the ability to inhibit bacteria such as Escherichia coli (ATCC 11775), Vibrio parahaemolyticus (ATCC 17802), Staphylococcus aureus subsp. aureus (ATCC 55804), and Bacillus cereus (ATCC 13061) at concentrations of 20 w/v%. The analysis of the nanocomposite microstructures exhibited a heterogeneous sponge-like morphology. The mechanical properties showed that the addition of 5 wt.% n-BG increased the elastic modulus of PLA by ca. 91.3% (from 1.49 ± 0.44 to 2.85 ± 0.99 MPa) and influenced the resorption capacity, as shown by histological analyses in biomodels. The incorporation of n-BGs decreased the PLA crystallinity (from 7.1% to 4.98%) and increased the glass transition temperature (Tg) from 53 °C to 63 °C. In addition, the n-BGs increased the thermal stability due to the nanoparticle's intercalation between the polymeric chains and the reduction in their movement. The histological implantation of the nanocomposites and the cell viability with HeLa cells higher than 80% demonstrated their biocompatibility character with a greater resorption capacity than PLA. These results show the potential of PLA/n-BGs nanocomposites for biomedical applications, especially for long healing processes such as bone tissue repair and avoiding microbial contamination.

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The leaves of Olea europaea as agricultural waste represent a convenient source of antioxidants. In combination with supercritical CO2 (scCO2), assisted impregnation is an interesting strategy for the preparation of biomedical devices with specific bioactivity. For this purpose, 3D-printable filaments of thermoplastic polyurethane (TPU) and polylactic acid (PLA) were employed for the supercritical impregnation of ethanolic olive leaves extract (OLE) for biomedical application. The extraction of OLE was performed using pressurized liquids. The effect of pressure (100-400 bar), temperature (35-55 °C), and the polymer type on the OLE impregnation and the swelling degree were studied including a morphological analysis and the measurement of the final antioxidant activity. All the studied variables as well as their interactions showed significant effects on the OLE loading. Higher temperatures favored the OLE loading while the pressure presented opposite effects at values higher than 250 bar. Thus, the highest OLE loadings were achieved at 250 bar and 55 °C for both polymers. However, TPU showed c.a. 4 times higher OLE loading and antioxidant activity in comparison with PLA at the optimal conditions. To the best of our knowledge, this is the first report using TPU for the supercritical impregnation of a natural extract with bioactivity.

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The development of scaffolds for cell regeneration has increased because they must have adequate biocompatibility and mechanical properties to be applied in tissue engineering. In this sense, incorporating nanofillers or essential oils has allowed new architectures to promote cell proliferation and regeneration of new tissue. With this goal, we prepared four membranes based on polylactic acid (PLA), polycaprolactone (PCL), titanium dioxide nanoparticles (TiO2-NPs), and orange essential oil (OEO) by the drop-casting method. The preparation of TiO2-NPs followed the sol-gel process with spherical morphology and an average size of 13.39 nm ± 2.28 nm. The results show how the TiO2-NP properties predominate over the crystallization processes, reflected in the decreasing crystallinity percentage from 5.2% to 0.6% in the membranes. On the other hand, when OEO and TiO2-NPs are introduced into a membrane, they act synergistically due to the inclusion of highly conjugated thermostable molecules and the thermal properties of TiO2-NPs. Finally, incorporating OEO and TiO2-NPs promotes tissue regeneration due to the decrease in inflammatory infiltrate and the appearance of connective tissue. These results demonstrate the great potential for biomedical applications of the membranes prepared.

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Purpose: To evaluate in-vivo degradation of two bioabsorbable interference screws. Methods: Twenty-two crossbred Santa Inês ewes were used. A poly-DL-lactide (PDLLA) screw (70%/30%) was inserted in the right pelvic limb, and a PDLLA screw (70%) + ß-tri-calcium phosphate (ß-TCP) (30%) in the left pelvic limb. Animals were euthanized at one, four, seven and a half and 18 months after surgery. Plain radiography, computed tomography (CT), microCT, and histological analysis were accomplished. Results: PDLLA screw was hypodense at all evaluation moments, but with progressive density increase along the central axis, whereas PDLLA/ß-TCP was initially hyperdense and progressively lost this characteristic. No adverse reactions were observed on histological evaluation. Conclusions: The inclusion of ß-TCP favors screw degradation since the PDLLA/ß-TCP screws evidenced a more intense degradation process than the PDLLA screws at the last evaluation. PDLLA screws showed higher bone production, evident around the screw thread, inside the lateral perforations, and in the central canal, whereas the PDLLA/ß-TCP screws presented less bone tissue at the implantation site.

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