Considerable efforts have been spent on environmentally friendly particles for the encapsulation of essential oils. Polymeric particles were developed to encapsulate the essential oil from Piper nigrum based on gelatin and poly–ε–caprolactone (PCL) carriers. Gas Chromatography ((Flame Ionization Detection (GC/FID) and Mass Spectrometry (GC/MS)), Atomic Force Microscopy (AFM), Nanoparticle Tracking Analysis (NTA), Confocal Laser Scanning Microscopy (CLSM), Attenuated Total Reflectance–Fourier-transform Infrared Spectroscopy (ATR–FTIR), and Ultraviolet–Visible (UV–VIS) spectroscopy were used for the full colloidal system characterization. The essential oil was mainly composed of β-caryophyllene (~35%). The stability of the encapsulated systems was evaluated by Encapsulation Efficiency (EE%), electrical conductivity, turbidity, pH, and organoleptic properties (color and odor) after adding different preservatives. The mixture of phenoxyethanol/isotialzoni-3-one (PNE system) resulted in enhanced stability of approximately 120 and 210 days under constant handling and shelf-life tests, respectively. The developed polymeric system presented a similar controlled release in acidic, neutral, or basic pH, and the release curves suggested a pulsatile release mechanism due to a complexation of essential oil in the PCL matrix. Our results showed that the developed system has potential as an alternative stable product and as a controlling agent, due to the pronounced bioactivity of the encapsulated essential oil.

Biodegradable particles were developed using poly-ε-caprolactone and gelatin carriers containing different concentrations of Allium sativum essential oil (EO) (360 µg/mL, 420 µg/mL, and 460 µg/mL). Atomic force microscopy was useful to evaluate the particles’ surface based on morphological parameters. The particles’ size varied from 150 nm to 300 nm. The diameter was related to the increase of the particles’ height as a function of the EO concentration, influencing the roughness of the surface core values (from 20 to 30 nm) and surface irregularity. The spatial parameters Str (texture aspect ratio) and Std (texture direction) revealed low spatial frequency components. The hybrid parameters Sdq (root mean square gradient) and Sdr (interfacial area ratio) also increased as a function of the EO concentration, revealing fewer flat particles. On the other hand, the functional parameters (inverse areal material ratio and peak extreme height) suggested differences in surface irregularities. Higher concentrations of EO resulted in greater microtexture asperity on the particles’ surface, as well as sharper peaks. The nanoscale morphological surface analysis allowed the determination of the most appropriate concentration of encapsulated EO, influencing statistical surface parameters.

Microfibers are important to several areas of human lifestyle, and the knowledge about their physicochemical characteristics allows for proposing new technological applications. The in natura microfiber of Ochroma pyramidale fruit (IN sample) and its extracted pulp (PU sample) were evaluated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry and Differential Scanning Calorimetry (TG/dTG and DSC). Microfibers were composed mainly of (68 ± 1)% holocellulose, (35.8 ± 0.1)% cellulose, (32 ± 3)% lignin and (3.7 ± 0.3)% extractives. The XRD pattern of the PU sample revealed that the mercerization process resulted in the change of the cellulose crystal structure from Iα type (triclinic) to type II (monoclinic). The SEM technique showed that the IN sample presented regular cylindrical/hollow-shaped wire-like microfibers with diameters ranging from 5 µm to 25 µm. However, the mercerization process changed their natural morphology. A significant change in the FTIR spectra after the removal of hemicellulose and lignin components was observed: weak bands at 1739 cm⁻¹ (C=O stretching of lignin and hemicellulose fractions), 1463 cm⁻¹ (CH₃ of lignin) and 1246 cm⁻¹ (C-O of lignin) were still observed in the PU sample, indicating that the lignin was not completely removed due to the natural difficulty of isolating pure cellulose. The TG/dTG and DSC evaluation revealed a temperature increase of the second thermal event (starting at 235 °C) in the PU sample, which was assigned to the cellulose and residual hemicellulose degradation. Then, this work aimed to disseminate and characterize a microfiber with unusual characteristics still little explored by the scientific community, as well as its cellulosic pulp, providing information that may be useful in its application in different industries, enabling the positive development of new biocompatible, renewable and sustainable materials.

A new systematic structural study was performed using the Atomic Force Microscopy (AFM) reporting statistical parameters of polymeric particles based on gelatin and poly-ε-caprolactone (PCL) containing essential oil from Lippia origanoides. The developed biocides are efficient alternative controlling agents of Conotrachelus humeropictus and Moniliophtora perniciosa, the main pests of Theobroma grandiflorum. Our results showed that the particles morphology can be successfully controlled by advanced stereometric parameters, pointing to an appropriate concentration of encapsulated essential oil according to the particle surface characteristics. For this reason, the absolute concentration of 1000 µg·mL⁻¹ (P₁₀₀₀ system) was encapsulated, resulting in the most suitable surface microtexture, allowing a faster and more efficient essential oil release. Loaded particles presented zeta potential around (–54.3 ± 2.3) mV at pH = 8, and particle size distribution ranging from 113 to 442 nm. The hydrodynamic diameter of 90% of the particle population was found to be up to (405 ± 31) nm in the P₁₀₀₀ system. The essential oil release was evaluated up to 80 h, with maximum release concentrations of 63% and 95% for P₅₀₀ and P₁₀₀₀, respectively. The best fit for the release profiles was obtained using the Korsmeyer–Peppas mathematical model. Loaded particles resulted in 100% mortality of C. humeropictus up to 48 h. The antifungal tests against M. perniciosa resulted in a minimum inhibitory concentration of 250 µg·mL⁻¹, and the P₁₀₀₀ system produced growth inhibition up to 7 days. The developed system has potential as alternative controlling agent, due to its physical stability, particle surface microtexture, as well as pronounced bioactivity of the encapsulated essential oil.

Anais do XXIX Congresso de Iniciação Científica da UFAM (978-65-5941-092-7) - Estudo Das Propriedades Termomecânicas Do Phb/Lignina Desenvolvidos Através Mistura Mecânica