Poly Lactic Acid Nanoparticles Research Articles

Comparison of passive targeted delivery of inorganic and organic nanocarriers among different types of tumors

In this study, we have considered four types of nanoparticles (NPs): polylactic acid (PLA), gold (Au), calcium carbonate (CaCO3), and silica (SiO2) with similar sizes (TEM: 50–110 nm and DLS: 110–140 nm) to examine their passive accumulation in three different tumors: colon (CT26), melanoma (B16-F10), and breast (4T1) cancers. Our results demonstrate that each tumor model showed a different accumulation of NPs, in the following order: CT26 > B16-F10 > 4T1. The Au and PLA NPs were evidently characterized by a higher delivery efficiency in case of CT26 tumors compared to CaCO3 and SiO2 NPs. The Au NPs demonstrated the highest accumulation in B16-F10 cells compared to other NPs. These results were verified using SPECT, ex vivo fluorescence bioimaging, direct radiometry and histological analysis. Thus, this work contributes to new knowledge in passive tumor targeting of NPs and can be used for the development of new strategies of tumor delivery.

An intelligent indicating label using mulberry pigment, polylactic acid and rutile TiO2 nanoparticle for monitoring the freshness of cold fresh pork

The purpose of this work is to develop a new type of intelligent indicating label with high sensitivity to volatile bioamine, anti-ultraviolet light and anti-pigment leakage characteristics by electrospinning for real-time visual monitoring the freshness of cold fresh pork. By investigating pH discoloration sensitivity and light stability of plant pigments with different structures, mulberry pigment was selected as the indicator of indicating label. The content of label components (mulberry pigment, polylactic acid and TiO2 nanoparticle) significantly affected label performance (light stability, responsiveness to trimethylamine, and anti-leakage of mulberry pigment), and the optimal component content was determined to be 6.01% (w/w) of polylactic acid, 0.62% (w/w) of TiO2 nanoparticles and 0.29% (w/w) of mulberry pigment by response surface test based on label performance as response value. A close correlation (the correlation coefficient R values of 0.86–0.97) between the total color difference (ΔE) of the label and the freshness indexes (total plate count, total volatile basic nitrogen content, pH, thiobarbituric acid value and sensory score) of cold fresh pork during cold storage was revealed, and the freshness level of unknown pork samples could be well quantitatively predicted by partial least squares regression models with the determination coefficient (R2) values of 0.89–0.92, facilitating producers, dealers and consumers to know pork quality promptly.

HepG2 exosomes coated luteolin nanoparticles remodeling hepatic stellate cells and combination with sorafenib for the treatment of hepatocellular carcinoma

BackgroundHepatocellular carcinoma (HCC) is a common malignant tumor with high mortality and recurrence rate. The efficacy of the first-line drug sorafenib is impeded by drug resistance, which is closely related to activated hepatic stellate cells (HSCs). The natural product luteolin is good at alleviating the activation of HSC. However, its clinical application is limited to poor solubility, bioavailability and lacking of HSCs targeting effects. This study aims to construct luteolin-loaded biomimetic nanoparticles based on HepG2 exosomes for targeting HSCs and enhancing the therapeutic effects of sorafenib on HCC.MethodsThe HepG2 exosomes extracted were identified by size distribution, Zeta potential and characteristic proteins. Luteolin-loaded polylactic acid-glycolic acid (PLGA) nanoparticles (Lut-NPs) were prepared and wrapped by HepG2 exosomes to form biomimetic nanoparticles (Exo-Lut-NPs). A HepG2 cell sorafenib-resistant model induced by LX2 cell conditioned medium (CM) was established to evaluate the effects of Exo-Lut-NPs on reversing sorafenib-resistant in vitro. And the combined therapeutic effects of Exo-Lut-NPs with sorafenib were evaluated on a HepG2/LX2 subcutaneous xenograft tumor model in vivo.ResultsThe particle size, drug loading capacity and encapsulation efficiency of Exo-Lut-NPs were 165 ± 10 nm, 2.6 ± 0.2% and 56.9 ± 4.3%, respectively. The in vitro HepG2 sorafenib-resistant model was induced by the CM of LX2 cells, and the results showed that Exo-Lut-NPs partially reversed the sorafenib resistance of HepG2 cells by affecting the CM of LX2 cells. The combined therapy of Exo-Lut-NPs with sorafenib markedly suppressed tumor growth in a HepG2/LX2 subcutaneous xenograft tumor model.ConclusionsThis study suggests that the Exo-Lut-NP is a novel and promising biomimetic delivery system which can combine with sorafenib for HCC therapy.

Magnetic scaffold constructing by micro-injection for bone tissue engineering under static magnetic field

The utilization of static magnetic fields in conjunction with tissue engineering scaffolds has demonstrated significant potential in the restoration of bone defects. However, previous techniques used for fabricating magnetic tissue engineering scaffolds have shown certain shortcomings that require further investigation. In this study, a series of scaffolds made from a combination of polylactic acid (PLA), polycaprolactone (PCL), and iron tetraoxide (Fe3O4) nanoparticles were designed and prepared using the microinjection molding technique. The composite scaffolds, which were doped with nanoparticles and fabricated through microinjection, exhibited exceptional physicochemical properties and biocompatibility. Additionally, the PLA/PCL/Fe3O4 scaffolds were found to promote the proliferation and adhesion of bone marrow cells (BMSCs) under relatively low magnetic fields (25–30 mT). These findings suggest that PLA/PCL/Fe3O4 scaffolds hold great potential for use in bone tissue engineering applications.

Preparation of photoresponsive lanthanide aluminate-immobilized nanofibers from recycled bioplastic via solution blowing spinning for optical authentication labeling

Photochromism is an intriguing technology to enhance the authentication of various commercial materials. In order to produce a transparent authentication film, it is also significant to improve the engineering process of anti-counterfeiting materials. In contrast to electrospinning, the solution blowing spinning (SBS) technique has been recently developed to produce nanofibers at low-cost and high yield with no need to apply high voltage. It has been essential to reduce the toxic pollution caused by plastic waste. Herein, we develop a photoluminescent nanofibrous membrane from recycled polylactic acid (PLA) waste and nanoparticles of strontium aluminate (NSA) by using the simple SBS technique. We investigated the potential use of the NSA@PLA composite nanofibers for photochromic anti-counterfeiting driven by ultraviolet light. Encapsulating the nanoparticle form of the strontium aluminate phosphor into polylactic acid nanofibers is necessary to ensure the transparent characteristic of the nanofibrous film. The film transparency can be further improved by the efficient dispersion of NSA without aggregation in the polylactic acid solution. Nanofibrous membranes with varying emission characteristics were produced by varying the NSA ratio. Both of X-ray diffraction (XRD) and Transmission electron microscopy (TEM) demonstrated the morphology of NSA to show diameters of 5–12 nm. The morphologies of the nanofibrous membranes were examined using various analytical methods, including energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence spectroscopy (XRF) and scanning electron microscopy (SEM). The mechanical characteristics and optical luminescence were also examined. SEM analysis of the NSA@PLA nanofibers showed diameters of 100–220 nm. The NSA@PLA nanofibrous membranes exhibited an emission peak at 518 nm upon excitation at 365 nm. The contact angles of the NSA@PLA nanofibrous membranes increased from 138.2° to 144.5° as the NSA concentration was increased, indicating an improved superhydrophobicity. Exposure to ultraviolet light caused the transparent nanofibers to undergo a rapid and strongly reversible photochromism to greenish emission. The present study can be reported as an easy and efficient approach to create anti-counterfeiting materials that offer a perfect market with social and financial profits.

NANOPARTICLE ENCAPSULATION OF THE SPECIALIZED PRO-RESOLVING MEDIATOR MARESIN-2: A NOVEL APPROACH FOR PROMOTING MUCOSAL REPAIR IN THE INTESTINE

Abstract Epithelial cells form protective barriers at mucosal surfaces and play a critical role in maintaining tissue homeostasis. Active inflammation in inflammatory bowel disease (IBD) is associated with epithelial barrier disruption and mucosal erosions/wounds that contribute to the inflammatory response and disease symptoms. Therefore, efficient repair of epithelial erosions/wounds is crucial for restoring intestinal barrier function and resolving mucosal inflammation. In response to injury, epithelial cells proliferate and migrate to cover denuded surfaces and restore critical barrier properties. Resident and recruited immune cells at sites of injury release factors that play an important role in orchestrating mucosal repair. Bioactive lipid mediators released by leukocytes, including leukotrienes and specialized pro-resolving mediators (SPMs), regulate epithelial signaling pathways to influence mucosal repair processes. Liquid chromatography-mass spectrometry (LCMS) analyses of healing colonic mucosal wounds performed to detect SPMs identified high levels of MaR2 in healing colonic wounds. In vitro studies using primary colonic epithelial cells revealed MaR2-driven increases in epithelial wound repair that were potentiated by the pro-inflammatory cytokines TNFα and IFNγ. While MaR2 increased epithelial migration by activating cell matrix adhesion proteins, including Src-paxillin and focal adhesion kinase, we did not observe any influence of MaR2 on the activation of cyclin D1/D2 or on epithelial proliferation. Importantly, in vivo studies demonstrated enhanced colonic mucosal wound repair and recovery from dextran sulfate-induced colitis in mice administered MaR2. Given the thermolabile nature of MaR2 (and associated ultracold storage requirements), thermostable polylactic acid (PLA) nanoparticles (NP) containing MaR2 (PLA MaR2) were generated. PLA MaR2 nanoparticles retained bioactivity following extended storage at room temperature and exhibited potent effects on in vivo colonic biopsy induced wound repair. Taken together these data reveal that thermostable MaR2 containing nanoparticles represent a promising new therapeutic approach for regenerating epithelial barrier function and restoring mucosal homeostasis in individuals with IBD.

Membrane fluidity properties of lipid-coated polylactic acid nanoparticles.

Lipid coating is considered a versatile strategy to equip nanoparticles (NPs) with a biomimetic surface coating, but the membrane properties of these nanoassemblies remain in many cases insufficiently understood. In this work, we apply C-Laurdan generalized polarization (GP) measurements to probe the temperature-dependent polarity of hybrid membranes consisting of a lipid monolayer adsorbed onto a polylactic acid (PLA) polymer core as function of lipid composition and compare the behavior of the lipid coated NPs (LNPs) with that of liposomes assembled from identical lipid mixtures. The LNPs were generated by nanoprecipitation of the polymer in aqueous solutions containing two types of lipid mixtures: (i) cholesterol, dipalmitoylphosphatidylcholine (DPPC), and the ganglioside GM3, as well as (ii) dioleoylphosphatidylcholine (DOPC), DPPC and GM3. LNPs were found to exhibit more distinct and narrower phase transitions than corresponding liposomes and to retain detectable phase transitions even for cholesterol or DOPC concentrations that yielded no detectable transitions in liposomes. These findings together with higher GP values in the case of the LNPs for temperatures above the phase transition temperature indicate a stabilization of the membrane through the polymer core. LNP binding studies to GM3-recognizing cells indicate that differences in the membrane fluidity affect binding avidity in the investigated model system.

Astaxanthin-loaded polylactic acid-glycolic acid nanoparticles ameliorate ulcerative colitis through antioxidant effects.

Astaxanthin (AST) is a type of carotenoid with strong antioxidant effects. However, the development and use of AST are limited by its water insolubility and low bioavailability. This study aims to investigate whether AST@PLGA can inhibit UC and reveal its possible mechanism. We tested the particle size, polydispersity index, and zeta potential of AST@PLGA. Then, the in vitro release and antioxidant capacity of AST@PLGA were tested. Finally, the mouse model of colitis was established and SOD, MDA, TNF-α, IL-1β, IL-6 and P38 as well as ERK were detected from mice. Particle size, polydispersity index and zeta potential of AST @PLGA were 66.78 ± 0.64 nm, 0.247 and -9.8 ± 0.53 mV, respectively, and were stable within 14 days. Then, it was observed that the AST@PLGA nanoparticles not only maintained the effect of AST but also had a sustained release effect. Experiments in mice showed that AST@PLGA effectively reduced MDA, TNF-α, IL-1β and IL-6 levels and increased SOD levels. AST@PLGA also downregulated the protein expression of P38 and ERK. The results showed the positive protective effect of AST@PLGA in inhibiting acute colitis. AST@PLGA nanoparticles have good stability and alleviating effect in colitis, which could be functional foods in the future.

B cell-targeted polylactic acidnanoparticles as platform for encapsulating jakinibs: potential therapeutic strategy for systemic lupus erythematosus.

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 30days. 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, proliferationand 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 thepotential ofPLA NPsto regulate autoreactive B cells, offering a novel therapeutic avenue for autoimmune diseases.

Nanoparticle formulation for intra-articular treatment of osteoarthritic joints

Based on a proven concept of using nanoparticles to lubricate an articulating interface, we developed a set of formulations to demonstrate the feasibility of using polymeric nanoparticles as physical intervention for early stage osteoarthritis (OA). The biocompatible polymeric nanoparticles (NPs), namely polymethylmethacrylate (PMMA), polycaprolactone (PCL), and polylactic acid (PLA) were accompanied with hyaluronic acid (HA) and surface actives, of which the lubrication effect was examined between a steel ball and a silicone elastomer substrate to replicate the bone-cartilage contact. All three types of polymer nanoparticles were found to reduce the overall Coefficient of Friction (CoF), with PLA NPs being the most effective - providing a reduction up to 24.3%, which suggests that soft (low Young's modulus) nanoparticles are the most efficient frictional additives. Based on the data acquired, it is likely that surface deposited NPs could smooth the solid substrates, hyaluronic acid ensures bulk viscosity, and the surfactant enhances formulation stability. We suggest that surface adsorbed nanoparticles are beneficial in providing interfacial lubrication, which offers insight on the development of early stage intervention strategies for OA.

Supercritical-CO2-Assisted Electrospray for the Production of the PLA-Antibiotic-Sustained Drug-Delivery System

Supercritical CO2 (SC-CO2)-assisted electrospray has been successfully performed to obtain a sustained release of ceftriaxone sodium (CFX) from polylactic acid (PLA) nanoparticles. PLA nanoparticles ranged from 270 ± 70 to 310 ± 80 nm, when produced at 140 bar. CFX release in a phosphate-buffered solution ranged from about 5 min, when the pure antibiotic was tested, to a maximum of 1200 min when 140 bar and 4 wt% of PLA + CFX nanoparticles was used: operating at these process conditions, an increase of 240 times of the release time was observed and no interactions were produced between PLA and the antibiotic. The release curves were explained hypothesizing a two-step mass transfer mechanism consisting of polymer swelling and PLA ester bond cleavage.

Directed Evolution of Material Binding Peptide for Polylactic Acid-specific Degradation in Mixed Plastic Wastes.

In order to preserve our livelihood for future generations, responsible use of plastics in a climate-neutral and circular economy has to be developed so that plastics can be used in an environmentally friendly way by future generations. The prerequisite is that bioplastic polymers such as polylactic acid (PLA) can be efficiently recycled from petrochemical based plastic. Here, a concept in which accelerated PLA degradation in the mixed suspension of PLA and polystyrene (PS) nanoparticles has been achieved through an engineered material binding peptide. After comparison of twenty material binding peptides, Cg-Def is selected due to its PLA binding specificity. Finally, a suitable high-throughput screening system is developed for enhancing material-specific binding toward PLA in presence of PS. Through KnowVolution campaign, a variant Cg-Def YH (L9Y/S19H) with 2.0-fold improved PLA binding specificity compared to PS is generated. Contact angle and surface plasmon resonance measurements validated higher surface coverage of Cg-Def YH on PLA surface and the fusion of Cg-Def YH with PLA degrading enzyme confirmed the accelerated PLA depolymerization (two times higher than only enzyme) in mixed PLA/PS plastics.

Exploiting immunostimulatory mechanisms of immunogenic cell death to develop membrane-encapsulated nanoparticles as a potent tumor vaccine

Vaccine is one of the most promising strategies for cancer immunotherapy; however, there are no therapeutic cancer vaccine achieving significant clinical efficacy till now. The main limiting factors include the immune suppression and escape mechanisms developed by tumor and not enough capacity of vaccines to induce a vigorous anti-tumor immunity. This study aimed to develop a strategy of membrane-based biomimetic nanovaccine and investigate the immunological outcomes of utilizing the unique immunostimulatory mechanisms derived of immunogenic cell death (ICD) and of fulfilling a simultaneous nanoscale delivery of a highlighted tumor antigen and broad membrane-associated tumor antigens in the vaccine design. TC-1 tumor cells were treated in vitro with a mixture of mitoxantrone and curcumin for ICD induction, and then chitosan (CS)-coated polylactic co-glycolic acid (PLGA) nanoparticles loaded with HPV16 E744-62 peptides were decorated with the prepared ICD tumor cell membrane (IM); further, the IM-decorated nanoparticles along with adenosine triphosphate (ATP) were embedded with sodium alginate (ALG) hydrogel, And then, the immunological features and therapeutic potency were evaluated in vitro and in vivo. The nanovaccine significantly stimulated the migration, antigen uptake, and maturation of DCs in vitro, improved antigen lysosome escape, and promoted the retention at injection site and accumulation in LNs of the tumor antigen in vivo. In a subcutaneously grafted TC-1 tumor model, the therapeutic immunization of nanovaccine elicited a dramatical antitumor immunity. This study provides a strategy for the development of tumor vaccines.Graphical

Prolonged survival time of Daphnia magna exposed to polylactic acid breakdown nanoplastics.

Polylactic acid nanoparticles (PLA NPs) according to food and drug administration are biodegradable and biocompatible polymers that have received a lot of attention due to their natural degradation mechanism. Although there is already available information concerning the effects of PLA microplastic to aquatic organisms, the knowledge about PLA NPs is still vague. In the present study, we analyzed the chemical composition of engineered PLA NPs, daily used PLA items and their breakdown products. We show that PLA breakdown products are oxidized and may contain aldehydes and/or ketones. The breakdown produces nanosized particles, nanoplastics, and possibly other small molecules as lactide or cyclic oligomers. Further, we show that all PLA breakdown nanoplastics extended the survival rate in Daphnia magna in an acute toxicity assay, however, only PLA plastic cup breakdown nanoplastics showed a significant difference compared to a control group.

Biocompatibility Assessment of Polycaprolactone/Polylactic Acid/Zinc Oxide Nanoparticle Composites under In Vivo Conditions for Biomedical Applications.

The increasing demand for non-invasive biocompatible materials in biomedical applications, driven by accidents and diseases like cancer, has led to the development of sustainable biomaterials. Here, we report the synthesis of four block formulations using polycaprolactone (PCL), polylactic acid (PLA), and zinc oxide nanoparticles (ZnO-NPs) for subdermal tissue regeneration. Characterization by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) confirmed the composition of the composites. Additionally, the interaction of ZnO-NPs mainly occurred with the C=O groups of PCL occurring at 1724 cm-1, which disappears for F4, as evidenced in the FT-IR analysis. Likewise, this interaction evidenced the decrease in the crystallinity of the composites as they act as crosslinking points between the polymer backbones, inducing gaps between them and weakening the strength of the intermolecular bonds. Thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses confirmed that the ZnO-NPs bind to the carbonyl groups of the polymer, acting as weak points in the polymer backbone from where the different fragmentations occur. Scanning electron microscopy (SEM) showed that the increase in ZnO-NPs facilitated a more compact surface due to the excellent dispersion and homogeneous accumulation between the polymeric chains, facilitating this morphology. The in vivo studies using the nanocomposites demonstrated the degradation/resorption of the blocks in a ZnO-NP-dependant mode. After degradation, collagen fibers (Type I), blood vessels, and inflammatory cells continue the resorption of the implanted material. The results reported here demonstrate the relevance and potential impact of the ZnO-NP-based scaffolds in soft tissue regeneration.

Polylactic acid nanoparticles loaded with losartan potassium regulate the expression of ET-1 in acute kidney injury

This study explored specific mechanism of action for polylactic acid-loaded nanoparticles loaded with losartan potassium to regulate the expression of ET-1 in acute kidney injury. Preparation and identification of Polylactic acid nanoparticles (PLA-NP) loaded with losartan potassium (PLA-NP-LP) were herein performed. After establishment of acute kidney injury rat models, the rats were assigned into model group, PLA-NP group, losartan potassium group, PLA-NP-LP group, NF-kB agonist group, NF-kB inhibitor group, NF-kB agonist and inhibitor group respectively. After one week of intervention, rat kidney tissues were taken for Hematoxylin and Eosin (H&E) staining and Real-time Polymerase Chain Reaction (PCR) and Western blot were used to measure the levels of NF-kB and ET-1, along with analysis of levels of creatinine and blood urea nitrogen by an automatic biochemical analyzer. PLA-NP-LP nanoparticles was successfully prepared with good shape. The levels of creatinine and urea nitrogen, renal tubular dilation and epithelial edema in the PLA-NP-LP group were lowest (vs. model group and losartan Potassium group), with P < 0.05. PLA-NP-LP inhibited the expression of ET-1 and NF-kB, P < 0.05. The ET-1 expression level for rats in the NF-kB agonist combined with PLA-NP-LP group was higher (vs. PLA-NP-LP group). Moreover, the level of ET-1 decreased (P < 0.05). PLA-NP-LP can improve renal function of rats with acute kidney injury, reduce renal tubular epithelial edema, and downregulate ET-1 in the rat kidney, by inhibiting the expression of NF-kB.

The Sustained-released Polylactic Co-glycolic Acid Nanoparticles Loaded with Chlorhexidine as Antibacterial Agents Inside the Dental Implant Fixture.

Titanium-based implants are widely used due to their good biocompatibility and high corrosion resistance. Infections after implant placement are the main reason for the failure of implant treatment. Some recent studies have also shown that microbial contamination can occur at the implant-abutment level in implants with healthy or diseased surrounding tissue. The purpose of this study is to investigate the antibacterial effect of slow-release nanoparticles of polylactic co-glycolic acid (PLGA) loaded with chlorhexidine (CHX) inside the implant fixture. Thirty-six implants in three groups were examined in the bacterial culture environment. In the first group, PLGA/CHX nanoparticles; in the second group, the negative control group (distilled water) and in the third group, the positive control groups (chlorhexidine) were used. The bacterial suspensions, including Escherichia coli ATCC: 25922, Staphylococcus aureus ATCC: 6538 and Enterococcus faecalis ATCC: 29212 were used to investigate the antimicrobial effect of the prepared nanoparticles. The results showed that the use of PLGA/CHX nanoparticles significantly inhibited the growth of all three bacteria. Nanoparticles loaded with chlorhexidine had a significant decrease in the growth rate of all three bacteria compared to chlorhexidine and water. The lowest bacterial growth rate was observed in the Enterococcus faecalis/PLGA nanoparticles group, and the highest bacterial growth rate was observed in the Staphylococcus aureus/H2O group. The current study showed that the use of PLGA/CHX nanoparticles could significantly inhibit the growth of all three bacteria. Of course, the current study was conducted in vitro, and to obtain clinical results, we need to conduct a study on human samples. In addition, the results of this study showed that the chemical antimicrobial materials could be used in low concentrations and in a sustained- released manner in cases of dealing with bacterial infections, which can lead to better and targeted performance as well as reduce possible side effects.

Hyaluronic acid-modified and verteporfin-loaded polylactic acid nanogels promote scarless wound healing by accelerating wound re-epithelialization and controlling scar formation

Wound healing is a common occurrence. However, delayed healing and aberrant scarring result in pathological wound healing. Accordingly, a scarless wound healing remains a significant clinical challenge. In this study, we constructed hyaluronic acid (HA)-modified and verteporfin (VP)-loaded polylactic acid (PLA) nanogels (HA/VP-PLA) to promote scarless wound healing by accelerating wound re-epithelialization and controlling scar formation. Owing to the unique structure of HA incorporating and coating in VP-loaded PLA nanoparticles, HA/VP-PLA could be topically applied on wound to achieve targeted delivery to fibroblasts. Then, HA/VP-PLA released HA and lactic acid (LA) to stimulate the proliferation and migration of fibroblasts, as well as VP to inhibit Yes-associated protein (YAP) expression and nuclear localization to suppress fibrosis. In vitro (skin fibroblasts) and in vivo (rat and rabbit models) experiments strongly suggested that HA/VP-PLA promoted scarless wound healing by accelerating wound re-epithelialization and controlling scar formation. Therefore, our work provides a feasible strategy for scarless wound healing, and the sophisticated HA/VP-PLA exhibit a great potential for clinical applications.

Photothermal-Responsive Shape-Memory Magnetic Helical Microrobots with Programmable Addressable Shape Changes

Faced with complex and diverse tasks, researchers seek to introduce stimuli-responsive materials into the field of microrobots. Magnetic helical microrobots based on shape-memory polymers demonstrate excellent locomotion capability and programmable shape transformations. However, the stimulation method of shape changes is still dependent on the rising of ambient temperature and lacks the ability to address individuals among multiple microrobots. In this paper, magnetic helical microrobots were prepared based on polylactic acid and Fe3O4 nanoparticles, which demonstrated controlled locomotion under rotating magnetic fields and programmable shape changes in their length, diameter, and chirality. The transition temperature of shape recoveries was adjusted to a range above 37 °C. At 46 °C, helical microrobots had a fast shape change with a recovery ratio of 72% in a minute. The photothermal effect of Fe3O4 nanoparticles under near-infrared laser can actuate the shape recovery rapidly, with a recovery ratio of 77% in 15 s and 90% in a minute. The stimulation strategy also allows addressing among multiple microrobots, or even within a single microrobot, selectively stimulating one or a part to change its shape. Combined with the magnetic field, laser-addressed shape changes were used for precise deployment and individual control of microrobots. Multiple microrobots can be enriched at the targeted point, heating the ambient temperature over 46 °C. The shape changes of internal parts of microrobots help them to grasp and assemble objects. Such microrobots have great potential in biomedicine and micromanipulation.

Evaluation of the Antioxidant and Antimicrobial Potential of SiO2 Modified with Cinnamon Essential Oil (Cinnamomum Verum) for Its Use as a Nanofiller in Active Packaging PLA Films.

One of the main causes of food spoilage is the lipid oxidation of its components, which generates the loss of nutrients and color, together with the invasion of pathogenic microorganisms. In order to minimize these effects, active packaging has played an important role in preservation in recent years. Therefore, in the present study, an active packaging film was developed using polylactic acid (PLA) and silicon dioxide (SiO2) nanoparticles (NPs) (0.1% w/w) chemically modified with cinnamon essential oil (CEO). For the modification of the NPs, two methods (M1 and M2) were tested, and their effects on the chemical, mechanical, and physical properties of the polymer matrix were evaluated. The results showed that CEO conferred to SiO2 NPs had a high percentage of 2,2-diphenyl-l-picrylhydrazyl (DPPH) free radical inhibition (>70%), cell viability (>80%), and strong inhibition to E. coli, at 45 and 11 µg/mL for M1 and M2, respectively, and thermal stability. Films were prepared with these NPs, and characterizations and evaluations on apple storage were performed for 21 days. The results show that the films with pristine SiO2 improved tensile strength (28.06 MPa), as well as Young's modulus (0.368 MPa) since PLA films only presented values of 27.06 MPa and 0.324 MPa, respectively; however, films with modified NPs decreased tensile strength values (26.22 and 25.13 MPa), but increased elongation at break (from 5.05% to 10.32-8.32%). The water solubility decreased from 15% to 6-8% for the films with NPs, as well as the contact angle, from 90.21° to 73° for the M2 film. The water vapor permeability increased for the M2 film, presenting a value of 9.50 × 10-8 g Pa-1 h-1 m-2. FTIR analysis indicated that the addition of NPs with and without CEO did not modify the molecular structure of pure PLA; however, DSC analysis indicated that the crystallinity of the films was improved. The packaging prepared with M1 (without Tween 80) showed good results at the end of storage: lower values in color difference (5.59), organic acid degradation (0.042), weight loss (24.24%), and pH (4.02), making CEO-SiO2 a good component to produce active packaging.