Release Of Carvacrol Research Articles

Antimicrobial efficacy of carvacrol-loaded curdlan hydrogels for enhancing shelf-life in seafood packaging applications

As global warming and the energy crisis receive increasing attention, the development of ecofriendly functional food packaging materials has also garnered significant interest. In this study, curdlan was combined with foaming agents (Cremodan and xanthan) and a crosslinking agent (sodium trimetaphosphate) to form a porous curdlan hydrogel. The material properties of the curdlan hydrogels were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and a thermogravimetric analysis (TGA). Results showed that the 2 % curdlan hydrogel exhibited a high water content (96.2 %), and swelling (89.2 %) and reswelling abilities (89.5 %), with a distinctly porous structure and excellent thermostability. These properties make it suitable for loading carvacrol, resulting in the formation of a carvacrol/curdlan hydrogel. In the results of antimicrobial testing, the carvacrol/curdlan hydrogel showed greater antimicrobial properties against Shewanella putrefaciens (32.3 mm) and Vibrio harveyi (33.1 mm) compared to V. parahaemolyticus (24.5 mm) in inhibition zone test. Noteworthy was the certain degree of antimicrobial ability of the carvacrol/curdlan hydrogel, which continuously exhibited microbial inhibition of the total viable count (TVC) of the no-inoculated and V. parahaemolyticus-inoculated group on sea bass fillets during 6 days of storage. In addition, the carvacrol/curdlan hydrogel inhibited the S. putrefaciens-caused microbial spoilage of fish. However, the continuous antibacterial ability of carvacrol/curdlan hydrogel needs to be improved. In future work, changing the porous size of curdlan hydrogel to control the carvacrol release for elongating the durability and long-term usage will be accomplished to fit the need in functional packaging applications.

Carvacrol incorporation into novel controlled-release mucoadhesive systems for oral polymicrobial biofilm control

The aim of this study was to evaluate carvacrol antimicrobial activity in polymicrobial biofilms using a novel controlled-release mucoadhesive systems developed from biopolymers. The natural polymers gellan gum and sodium alginate were used in different concentrations for the development of films, tablets and microparticles containing carvacrol. The systems were characterized as regard their morphological characteristics, carvacrol release and mucoadhesion. Furthermore, the antimicrobial activity of the systems was evaluated on polymicrobial biofilms through biomass quantification and microbial viability assessment. Carvacrol release profile from films, tablets and microparticles was similar; nearly 100% of the carvacrol was released within 15 min. Films showed the best mucoadhesion values. Scanning Electron Microscopy images showed that the films presented a continuous and smooth surface, and the tablets showed a continuous surface with a polymer web appearance. The microparticles were spherical in shape. The films containing carvacrol showed the highest biomass and microbial viability reduction, followed by the tablets. The findings of this study showed that carvacrol incorporated into films and tablets presented antimicrobial activity on polymicrobial biofilm. Controlled-release mucoadhesive systems is a process little explored in dentistry, being the differential of this work, and with great innovative potential for the management of dental diseases.

Layer-by-layer assembly of modified halloysite nanotube using chitosan and sodium alginate to control the release of carvacrol and improve its stability

This study focused on the encapsulation of modified halloysite nanotubes (AHNT) using sodium alginate (SA) and chitosan (CS) through a layer-by-layer assembly technique. The objective was to develop new composites (CPs) that could control the release of carvacrol (Car) and enhance its stability. The influence of various conditions on the microstructure, chemical properties, and slow-release effects of the CPs was examined by adjusting the pH and concentration of the CS solution. The results indicated that the CPs (CS4.5–1), created with a CS solution concentration of 1 mg/mL at a pH of 4.5, in conjunction with a 1 mg/mL SA solution, demonstrated a superior encapsulation structure and a loading efficiency of 26.33 %. In vitro release experiments confirmed that the CPs exhibited effective slow-release properties for Car. Furthermore, the CS4.5–1 composite provided a physical barrier that resulted in the retention of 94.90 % and 83.61 % of Car after 6 h of exposure to UV light and heat, respectively. Antimicrobial and antioxidant assays indicated that CS4.5–1/Car possessed significant antioxidant properties and effectively inhibited the growth of E. coli and S. aureus. Consequently, the prepared CPs have the potential to enhance the bioactivity of active compounds and may be beneficial for food preservation and other applications.

Bone Healing via Carvacrol and Curcumin Nanoparticle on 3D Printed Scaffolds.

Carvacrol is a potent antimicrobial and anti-inflammatory agent, while curcumin possesses antioxidant, anti-inflammatory, and anticancer properties. These phytochemicals have poor solubility, bioavailability, and stability in their free form. Nanoencapsulation can reduce these limitations with enhanced translational capability. Integrating nanocarriers with 3D-printedcalcium phosphate (CaP)scaffolds presents a novel strategy for bone regeneration. Carvacrol and curcumin-loaded nanoparticles (CC-NP) synthesized with melt emulsification produced negatively charged, monodispersed particles with a hydrodynamic diameter of ≈127nm. Their release from the scaffold shows a biphasic release under physiological and acidic conditions. At pH 5.0, the CC-NP exhibits a 53% release of curcumin and nearly 100% release of carvacrol, compared to 19% and 36% from their respective drug solutions. At pH 7.4, ≈40% of curcumin and 76% of carvacrol releases, highlighting their pH-sensitive release mechanism. In vitro studies demonstrate a 1.4-fold increase in osteoblast cell viability with CC-NP treatment. CC-NP exhibit cytotoxic effects against osteosarcoma cells, reducing cell viability by ≈2.9-fold. The antibacterial efficacy of CC-NP evaluated against Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) exhibiting 98% antibacterial efficacy. This approach enhances therapeutic outcomes and minimizes the potential side effects associated with conventional treatments, paving the way for innovative applications in regenerative medicine.

Potential of mesoporous silica nanoparticles for the delivery of anticancer bioactive compounds

The potential for dosing anticancer target molecules of silica nanoparticles with ordered mesoporosity (SiMONPs), 28 nm in diameter and surface area of 706 m2/g, was evaluated by the loading and release of carvacrol, chloroquine, and rhodamine-B. The ligand–protein interaction (BRAF oncogene) was determined by docking. The fine structure of the SiMONPs with nanometric porosity allowed a slow and progressive release according to the passive diffusion mechanism. The most favorable anticancer interaction was displayed by carvacrol with a ligand efficiency value of −6.7 kcal/mol. At the same time, chloroquine and rhodamine-B had values of −5.0 kcal/mol and −3.4 kcal/mol, severally. The target displayed a “preference” to interact first with the SiMONPs rather than with carvacrol. The material could be dosed at 0.0009 mg/h for a week under PBS medium conditions, so the material resulted suitable for dosing and controlling the growth of skin cancer cells.

Study of the Resistance of Staphylococcus aureus Biofilm, Biofilm-Detached Cells, and Planktonic Cells to Microencapsulated Carvacrol Used Alone or Combined with Low-pH Treatment.

Microbial biofilms pose severe problems in the medical field and food industry, as they are the cause of many serious infections and food-borne diseases. The extreme biofilms' resistance to conventional anti-microbial treatments presents a major challenge to their elimination. In this study, the difference in resistance between Staphylococcus aureus DSMZ 12463 biofilms, biofilm-detached cells, and planktonic cells against microcapsules containing carvacrol was assessed. The antimicrobial/antibiofilm activity of low pH disinfection medium containing the microencapsulated carvacrol was also studied. In addition, the effect of low pH on the in vitro carvacrol release from microcapsules was investigated. The minimum inhibitory concentration of microencapsulated carvacrol was 0.625 mg mL-1. The results showed that biofilms exhibited greater resistance to microencapsulated carvacrol than the biofilm-detached cells and planktonic cells. Low pH treatment alone, by hydrochloric acid addition, showed no bactericidal effect on any of the three states of S. aureus strain. However, microencapsulated carvacrol was able to significantly reduce the planktonic cells and biofilm-detached cells below the detection limit (no bacterial counts), and the biofilm by approximatively 3 log CFU mL-1. In addition, results showed that microencapsulated carvacrol combined with low pH treatment reduced biofilm by more than 5 log CFU mL-1. Thus, the use of microencapsulated carvacrol in acidic environment could be a promising approach to combat biofilms from abiotic surfaces.

Design of an antioxidant powder additive based on carvacrol encapsulated into a multilayer chitosan-alginate-maltodextrin emulsion

Carvacrol has demonstrated antioxidant activity; however, its high volatility and low water solubility limit its direct application in food matrices. Then, an effective encapsulation system is required to protect it. This study aimed to design and characterize a carvacrol-based additive encapsulated in a spray-dried multilayer emulsion based on chitosan/sodium alginate/maltodextrin. Spray-drying temperature of 120 °C and 3 %(w/w) maltodextrin content maximized both encapsulation efficiency (~97 %) and loading capacity (~53 %). The powder's antioxidant properties were evaluated in two food simulant media: water (SiW) and water-ethanol (SiD). The highest antioxidant activity was observed in SiW for both ABTS•+ (8.2 ± 0.3mgEAG/g) and FRAP (4.1 ± 0.2mgEAG/g) methods because of the reduced release of carvacrol in SiD vs. SiW, as supported by micro- and macrostructural observations by SAXS and microscopy, respectively. An increase from 143 to 157 °C attributable to carvacrol protection and Tg = 44.4 °C (> ambient) were obtained by TGA and DSC, respectively. FT-IR confirmed intermolecular interactions (e.g. -COO− and -NH3+) as well as H-bonding formation. High water solubility (81 ± 3 %), low hygroscopicity (8.8 ± 0.2 %(w/w), poor flowability (CI:45 ± 4), and high cohesiveness (HR:1.8 ± 0.1) between particles were achieved, leading to a powdered antioxidant additive with high potential for applications which required avoiding/reducing oxidation on hydrophilic and hydrophobic food products.

Synthesis, characterization, and evaluation of the anticancer properties of pH-responsive carvacrol-zinc oxide quantum dots on breast cancer cell line (MDA-MB-231).

Since most solid tumors have a low pH value, a pH-responsive drug delivery system may offer a broad method for tumor-targeting treatment. The present study is used to analyze the anticancer activity of carvacrol-zinc oxide quantum dots (CVC-ZnO QDs) against breast cancer cells (MDA-MB-231). CVC-ZnO QDs demonstrate pH responsive and are specifically released within the acidic pH tumor microenvironment. This property enables targeted drug delivery exclusively to cancer cells while minimizing the impact on normal cells. To the synthesized ZnO QDs, the CVC was loaded and then examined by X-ray diffraction, ultraviolet-visible, Fourier transform infrared spectrophotometer, scanning electron microscopy-energy dispersive X-ray, and transmission electron microscopy. For up to 20 h, CVC release was examined in different pH-buffered solutions. The results showed that carvacrol release was stable in an acidic pH solution. Further, cytotoxicity assay, antioxidant, and lipid peroxidation activity, reactive oxygen species, mitochondrial membrane potential, nuclear damage, and the ability of CVC-ZnO QDs to cause apoptosis were all examined. Apoptosis markers such as Bcl2, Bax, caspase-3, and caspase-9, were also studied. In conclusion, the CVC-ZnO QDs destabilized the MDA-MB-231cells under its acidic tumor microenvironment and regulated apoptosis.

Green Starch-Based Hydrogels with Excellent Injectability, Self-Healing, Adhesion, Photothermal Effect, and Antibacterial Activity for Promoting Wound Healing.

Hydrogel materials have proven valuable in wound healing, but improving the safety of these hydrogels is still challenging. Therefore, designing multifunctional natural polymeric-based hydrogels with excellent mechanical properties to replace toxic or potentially risky, refractory chemical polymer-based hydrogels such as polyacrylamide and polyethylene glycol is of particular significance. Here, a green starch-based hydrogel (Starch@Ca/CGC hydrogel) with injectability, self-healing, and instant adhesion was constructed by coordination interaction, electrostatic interaction, and intramolecular and intermolecular hydrogen bonds. Therein, natural bioactive small molecules gallic acid (GA) and carvacrol (CA) were coordinated with metal ions by the ultrasonic-triggered self-assembly and ionic cross-linking codriven strategy to prepare Cu-gallic acid-carvacrol nanospheres (CGC NPs), which conferred the hydrogel with near-infrared light (NIR)-controlled CA release and photothermal synergistic sterilization properties, as well as antioxidant and anti-infection capabilities. More importantly, the multifunctional hydrogel platforms could completely cover an irregular wound shape to prevent secondary injury and significantly accelerate wound healing under NIR with more skin appendages like hair follicles and blood vessels appearing. Therefore, it is expected that this starch-based hydrogel could serve as a competitive multifunctional dressing in the biomedical field, including bacteria-derived wound infection and other tissue repair.

Fabrication and characterization of polyvinyl alcohol/sodium alginate loaded carvacrol/silica hollow microspheres composite hydrogel as a colourimetric freshness indicator

A hybrid hydrogel consisting of anthocyanin (ATH), sodium alginate (SA), polyvinyl alcohol (PVA) and carvacrol (CA) loaded silica hollow microspheres (SC) was designed and fabricated as a colorimetric freshness indicator with antibacterial activity for monitoring meat spoilage. The microstructure and physicochemical properties of the hybrid hydrogels were investigated. The carvacrol could be loaded into silica microspheres, and the maximum degradation temperature raised to 179.6 °C due to the formation of hydrogen bonds between carvacrol and SiO2 microspheres. ATH and SC composite were well compatible with PVA/SA hydrogel with intramolecular hydrogen bond interactions. The three-dimensional network structure of the PVA/SA hydrogel was disrupted with increasing SC content, resulting in a gradual decrease in thermal stability, swelling capacity and tensile strength of the hydrogel. The SC-PVA/SA-ATH hydrogels exhibited satisfactory antibacterial ability against E. coli and S. aureus due to the effective release of CA from the hybrid hydrogel, and the inhibition ratio of SC3-PVA/SA-ATH was over 95%. The meat preservation experiment revealed that the hydrogel indicators exhibited distinctive color changes during the process of meat spoilage quality changes, indicating its promising application prospect in food preservation packaging.

Highly efficient anchoring of γ-cyclodextrin-MOFs on chitosan/cellulose film by in situ growth to enhance encapsulation and controlled release of carvacrol

Natural biopolymers have widespread applications in active food packaging attribute to their low-cost, easy availability, environmental-friendly, and excellent processibility. Extensive attention has been paid to integrate or modify nanostructures on biopolymer substrates to endow packaging materials with satisfactory preservation effects. Herein, green γ-cyclodextrin-metal-organic frameworks (γ-CD-MOFs) were successfully integrated on chitosan-cellulose (CS-CEL) polysaccharide film through in situ growth method and encapsulated with carvacrol (CAR) for controlled release active packaging. The γ-CD-MOFs were anchored on CS-CEL film depending on the coordination of glucose units in CS-CEL and potassium ion, which significantly improved the surface area of CS-CEL film from 1.0294 m2/g to 43.3458 m2/g. Furthermore, the molecular docking and 1H NMR spectra indicated that γ-CD-MOF has better complexing and stabilizing ability for CAR molecules than γ-CD. Additionally, the inhibition rate of this composite film against Escherichia coli, Staphylococcus aureus and Botrytis cinerea reached more than 99%. The film performed a humidity-controlled release effect on CAR and the release conformed to non-Fick diffusion. The shelf life of strawberries was extended to 7 days after treated with this film during storage. By incorporating the merits of natural biopolymers and MOFs, this novel active packaging offers great potential as a substitute for traditional packaging materials.

Functional, eco-friendly, and starch-based nanocarriers with sustained release of carvacrol for persistent control of tomato gray mold

Carvacrol (Car) is a promising botanical fungicide. However, the volatile and easily oxidizable characterization of Car hinders its practical application. Herein, an eco-friendly, starch-based nanopesticide (Car@ACS) was successfully constructed by encapsulating of Car within acetylated corn starch, enabling sustained release to prolong its efficacy. In vitro release experiments showed that the release of Car from commercial carvacrol soluble concentrate (Car SL) was 98.4% within 4 h, while that of Car@ACS released 36% within 4 h and 79% within 48 h, demonstrating the endowed sustained release property of the starch nanoparticles. Meanwhile, in vitro antimicrobial activity experiments revealed the fungicidal ability of the prepared Car@ACS and carvacrol technical (Car Tech) with the same concentration of active ingredient to be comparable Botrytis cinerea. In the 7-day pot experiment, the efficacy of the Car@ACS group (56.9%) against B. cinerea was significantly greater than that of the Car SL group (33.3%). In addition, the Car@ACS formulation improved the foliar retention of Car compared to Car SL in hydrophilic cucumber and hydrophobic peanut leaves. Finally, biosafety tests indicated that Car@ACS did not significantly affect the germination or growth of tomato seedlings. Therefore, the advantages of long-lasting disease control properties, improved foliar retention and eco-friendliness indicate that Car@ACS has significant potential to facilitate the application of volatile botanical fungicides.

Micelle encapsulated curcumin and piperine-laden 3D printed calcium phosphate scaffolds enhance in vitro biological properties

Limitations in the current clinical management of critical-sized osseous defects have driven the need for multifunctional bone constructs. The ideal bone scaffold should possess advanced microarchitecture, well-defined pore interconnectivity, and supply biological signals, which actively guide and control tissue regeneration while simultaneously preventing post-implantation complications. Here, a natural medicine-based localized drug delivery from 3D printed scaffold is presented, which offers controlled release of curcumin, piperine from nano-sized polymeric micelles, and burst release of antibacterial carvacrol from the coating endowing the scaffold with their distinct, individual biological properties. This functionalized scaffold exhibits improved osteoblast (hFOB) cell attachment, 4-folds higher hFOB proliferation, and 73% increased hFOB differentiation while simultaneously providing cytotoxicity towards osteosarcoma cells with 61% lesser viability compared to control. In vitro, early tube formation (p < 0.001) indicates that the scaffolds can modulate the endothelial cellular network, critical for faster wound healing. The scaffold also exhibits 94% enhanced antibacterial efficacy (p < 0.001) against gram-positive Staphylococcus aureus, the main causative bacteria for osteomyelitis. Together, the multifunctional scaffolds provide controlled delivery of natural biomolecules from the nano-sized micelle-loaded 3D printed matrix for significant improvement in osteoblast proliferation, endothelial formation, osteosarcoma, and bacterial inhibition, guiding better bone regeneration for post-traumatic defect repair.

Rheological Study of the Formation of Pullulan Hydrogels and Their Use as Carvacrol-Loaded Nanoemulsion Delivery Systems.

Hydrogels have been extensively studied as delivery systems for lipophilic compounds. Pullulan hydrogels were prepared, and their gelation kinetics were studied over time. Pullulan exhibited a relatively slow gelling reaction in basic medium (KOH) using trisodium metaphosphate (STMP) as a cross-linking agent, so capsules cannot be obtained by dripping as easily as in the case of alginate and chitosan. The kinetics of pullulan gelation were studied through rheological analysis over time. An optimal [Pullulan]/[KOH] ratio was found for a fixed [Pullulan]/[STMP] ratio. For this given relationship, gelling time measurements indicated that when the concentration of pullulan increased, the gelation time decreased from 60 min for 6% w/w pullulan to 10 min for 10% w/w. After the gel point, a hardening of the hydrogel was observed over the next 5 h. The formed hydrogels presented high degrees of swelling (up to 1800%). Freeze-dried gels were capable of being rehydrated, obtaining gels with rheological characteristics and visual appearance similar to fresh gels, which makes them ideal to be freeze-dried for storage and rehydrated when needed. The behavior of the hydrogels obtained as active ingredient release systems was studied. In this case, the chosen molecule was carvacrol (the main component of oregano oil). As carvacrol is hydrophobic, it was incorporated into the droplets of an oil-in-water nanoemulsion, and the nanoemulsion was incorporated into the hydrogel. The release of the oil was studied at different pHs. It was observed that as the pH increased (from pH 2 to pH 7), the released amount of carvacrol for the gel with pullulan 10% w/w reached 100%; for the other cases, the cumulative release amount was lower. It was attributed to two opposite phenomena in the porous structure of the hydrogel, where more porosity implied a faster release of carvacrol but also a higher degree of swelling that promoted a higher entry of water flow in the opposite direction. This flow of water prevented the active principle from spreading to the release medium.

Carvacrol release kinetics from cellulose acetate films and its antibacterial effect on the shelf life of cooked ham

Antibacterial films of the cellulose acetate (CA) and carvacrol were investigated regarding the migration to fat-like food simulants and the impact on the shelf life of the sliced cooked ham vacuum. Mathematical models described the bacterial growth in ham and the carvacrol release kinetics. The carvacrol antimicrobial activity against two food-borne spoilage bacteria was demonstrated. Carvacrol showed minimum inhibitory concentration (MIC) values of 293 and 194 μg/mL for Weisella viridescens and Pseudomonas fluorescens, respectively, and minimum bactericidal concentration (MBC) values of 488 μg/mL for both bacteria. The active CA-films with 5 and 10% carvacrol were used for bacterial inhibition and shelf life extension on the ham. Applying CA-film with 10% carvacrol decreased the growth rate and the final maximum population, increasing the latency phase of W. viridescens. It increased the ham shelf life by 10 days. The carvacrol migration demonstrated that obtaining films with long-acting and slow release to a food matrix is possible. In food fluids simulations, the migration was faster, with diffusion coefficients between 10−13 and 10−15 m2/s. The results demonstrate the CA-film with carvacrol as a potential active packaging to increase the shelf life of complex food matrix.

Kinetics of carvacrol release from active paper packaging for fresh fruits and vegetables under conditions of open and closed package

The carvacrol release kinetics from active packaging (including carvacrol-βcyclodextrin inclusion complex) was studied under the following possible scenarios found in fresh produce packaging and marketing facilities: different storage temperatures (2, 8, 15 and 22 ºC), relative humidity (60% and 95% RH), as well as different packaging conditions (open or closed). Release kinetics for the closed and open packaging systems were described using first-order and n-order power law kinetics, respectively. Increasing temperature and RH enhanced the carvacrol release rate. The release rate (k) increased by 1.3–1.7-fold when the RH was augmented from 60% to 95%. An initial release burst effect was observed with the highest k rate (0.14/2.0 × 10−2 1/dayn) under open active packaging at 8/15 ºC (95% RH). In conclusion, the use of active packaging will ensure a proper essential oil release, with even a higher initial release (burst effect) in open packages, leading to a potential extension of the product shelf life.

Characterization and sustained release study of starch-based films loaded with carvacrol: A promising UV-shielding and bioactive nanocomposite film

Present study was aimed to develop sustainable active films with starch/carvacrol for potential food packaging. The physicochemical, antioxidant, antibacterial and release kinetics were analyzed. The results demonstrated that carvacrol nanoemulsion (CNE) was uniformly dispersed in the film matrix and interacted with hydrogen bonds. The addition of carvacrol improved the thermal stability, UV shielding, water solubility and water vapor permeability of the films, but reduced their mechanical properties. Films prepared with CNE (≥10%) exhibited high antioxidant activity (>60%), and inhibition zones of the best antimicrobial activities achieved 28.6 ± 1.4 and 57.2 ± 3.7 (mm) against E. coli and S. aureus. The release kinetics of carvacrol from the nanocomposite films exhibited a higher carvacrol release in the acidic simulant than in the aqueous simulant at equilibrium. The dominant mechanism of carvacrol release was Fickian diffusion and showed minimal erosion. Overall, the sustainable composite films exhibited desirable physical properties and bioactivity, and could be used as edible materials for food preservation, especially for extending the shelf life of acidic foods.

Thymol and Carvacrol: Phenolic Monoterpenes Extracted from the Essential Oil of Thymus vulgaris as Natural Antimicrobial Guests of Nanoporous Crystalline Syndiotactic Polystyrene Fibers

AbstractThymol and carvacrol, relevant natural antimicrobial molecules, induce co‐crystallization and, in absence of any mechanical stretching, also high degrees of axial orientation on s‐PS amorphous fibers. The release of thymol and carvacrol from s‐PS co‐crystalline fibers has been analyzed to realize long‐term antimicrobial fabrics. Partition between isolated guest molecules, present in co‐crystalline phase or simply dissolved in the amorphous phase, has been investigated by FTIR and thermogravimetric measurements. These analyses have been confirmed by polarized FTIR spectra of axially oriented s‐PS films.

A functional SiO2-TiO2 mesoporous assembly designed for the controlled release of carvacrol

Mesoporous composites can be useful for the gentle release of biocides and fertilizers. Here, we study the structural, morphological, and drug-delivery advantages of SiO2-TiO2 (PST) particles synthesized by a hydrothermal method. The PST particles had a spherical-like assembly architecture, which was obtained by cobalt ions incorporation. Each assembly contains nanobars with acute or obtuse tip shape, notably in the sample with 0.5 wt% of Co. Drug loading/delivery evaluations were carried out using carvacrol (CVC) as biocidal molecule. PST composites functionalized with the triethanolamine presented higher load efficiencies of 30–37% and load capacities of 20–26%. A similar trend occurred for the release percentage of CVC. The PST samples without functionalization had a release of only 19–29% (at pH=7.4). After the TEOA functionalization, the release percentage was enhanced to 64–78%. Moreover, the PST had a maximum release percentage of 64.8% reached after only 3 min (at pH=7.4). In contrast, the PST doped with 1 wt% of Co reached the maximum release percentage of 64.8% after 24 h at pH=7.4. Hence, the results of this investigation demonstrate that the PST synthetized with Co and functionalized with TEOA could be used for the control of undesired weed and phytopathogens in cultivated plants by prolonging their delivery time of biocidal molecules.

Perimeter and carvacrol-loading regulate angiogenesis and biofilm growth in 3D printed PLA scaffolds.

Carvacrol is a natural low-cost compound derived from oregano which presents anti-bacterial properties against both Gram-positive and Gram-negative bacteria. In this work, carvacrol-loaded PLA scaffolds were fabricated by 3D printing as platforms to support bone tissue regeneration while preventing biofilm development. Scaffolds were printed with or without a perimeter (lateral wall) mimicking the cortical structure of bone tissue to further evaluate if the lateral interconnectivity could affect the biological or antimicrobial properties of the scaffolds. Carvacrol incorporation was performed by loading either the PLA filament prior to 3D printing or the already printed PLA scaffold. The loading method determined carvacrol localization in the scaffolds and its release profile. Biphasic profiles were recorded in all cases, but scaffolds loaded post-printed released carvacrol much faster, with 50-80% released in the first day, compared to those containing carvacrol in PLA filament before printing which sustained the release for several weeks. The presence or absence of the perimeter did not affect the release rate, but total amount released. Tissue integration and vascularization of carvacrol-loaded scaffolds were evaluated in a chorioallantoic membrane model (CAM) using a novel quantitative micro-computed tomography (micro-CT) analysis approach. The obtained results confirmed the CAM tissue ingrowth and new vessel formation within the porous structure of the scaffolds after 7days of incubation, without leading to hemorrhagic or cytotoxic effects. The absence of lateral wall facilitated lateral integration of the scaffolds in the host tissue, although increased the anisotropy of the mechanical properties. Scaffolds loaded with carvacrol post-printing showed antibiofilm activity against Staphylococcus aureus and Pseudomonas aeruginosa as observed in a decrease in CFU counting after biofilm detachment, changes in metabolic heat measured by calorimetry, and increased contact killing efficiency. In summary, this work demonstrated the feasibility of tuning carvacrol release rate and the amount released from PLA scaffolds to achieve antibiofilm protection without altering angiogenesis, which was mostly dependent on the perimeter density of the scaffolds.