In the modern world, many products are disposable or have a very short lifespan, while at the same time, those products are made from materials that will remain in the environment in the form of waste for hundreds or even thousands of years. It is a serious problem; non-biodegradable polymer wastes are part of environmental pollution and generate microplastics, which accumulate in the organisms of living beings. One of the proposed solutions is biodegradable polymers and their composites. In our work, three types of polylactide-based composites with plant-derived fillers: microcellulose powder, short flax fibers, and wood flour at 2 wt.% were prepared. Poly(lactic acid) (PLA)-based biocomposite properties were characterized in terms of mechanical and surface properties together with microscopic analysis and Fourier-transform infrared spectroscopy (FTIR), before and after a UV (ultraviolet)-light-aging process to determine the effects of each cellulose-based additive on the UV-induced degradation process. This research shows that the addition of a cellulose additive can improve the properties of the material in terms of the UV-aging process, but the form of the chosen cellulose form plays a crucial role in this case. The testing of physicochemical properties demonstrated that not only can mechanical properties be improved, but also the time of degradation under UV light exposure can be controlled by the proper selection of the reinforcing phase and the parameters of the extrusion and injection molding process. The obtained results turned out to be very interesting, not only in terms of the cost reduction of the biocomposites themselves, as mainly the waste from the wood industry was used as a low-cost filler, but also that the additive delays the aging process occurring during UV light exposure. Even a small, 2 wt.% addition of some of the tested forms of cellulose delayed surface degradation, which is one of the most important factors affecting the biodegradation process.

This study delves into the physicochemical properties of inorganic hydroxyapatite (HAp) and hybrid hydroxyapatite–chitosan (HAp-CTS) granules, also gold-enriched, which can be used as aggregates in biomicroconcrete-type materials. The impact of granules’ surface modifications with citric acid (CA) or polyethylene glycol (PEG) was assessed. Citric acid modification induced increased specific surface area and porosity in inorganic granules, contrasting with reduced parameters in hybrid granules. PEG modification resulted in a slight increase in specific surface area for inorganic granules and a substantial rise for hybrid granules with gold nanoparticles. Varied effects on open porosity were observed based on granule type. Microstructural analysis revealed increased roughness for inorganic granules post CA modification, while hybrid granules exhibited smoother surfaces. Novel biomicroconcretes, based on α-tricalcium phosphate (α-TCP) calcium phosphate cement and developed granules as aggregates within, were evaluated for compressive strength. Compressive strength assessments showcased significant enhancement with PEG modification, emphasizing its positive impact. Citric acid modification demonstrated variable effects, depending on granule composition. The incorporation of gold nanoparticles further enriched the multifaceted approach to enhancing calcium phosphate-based biomaterials for potential biomedical applications. This study demonstrates the pivotal role of surface modifications in tailoring the physicochemical properties of granules, paving the way for advanced biomicroconcretes with improved compressive strength for diverse biomedical applications.

Optical photothermal infrared (O-PTIR) microspectroscopy is an emerging label-free technique that achieves infrared super-resolution and has found widespread applications, primarily in soft materials. While the photothermal effect underlying O-PTIR has been extensively studied at room temperature, there was an open question whether the signal itself would benefit from a lower temperature, as the photoinduced heating could be more localized, thus increasing the signal. In this work, we integrated a temperature-controlled stage into an O-PTIR microscope, enabling the first spectroscopic measurements and imaging of samples at subzero temperatures down to -100 °C. Using tristearin, biological tissue, and polymer samples, we demonstrated that cooling significantly enhances the O-PTIR signal up to three times, with a maximum observed in the -20 to -40 °C range. This enhancement leads to an improved analytical sensitivity, reducing the limit of detection for a thin protein film from ca. 400 nm to ca. 300 nm. We further discuss the underlying physical mechanism with theoretical modeling, including thermal conductivity and heat dissipation effects, that contribute to the observed temperature-dependent signal amplification. Overall, this study establishes temperature-controlled O-PTIR as a powerful new approach for high-sensitivity, high-resolution infrared analysis, thereby expanding its applicability to a broader range of materials and experimental conditions.

Infrared imaging (IR), in addition to chemical specificity, has recently gained the capability to retrieve 3D molecular orientation information. When combined with IR super-resolution optical photothermal infrared (O-PTIR) spectroscopy, it enables unprecedented tracking of the three-dimensional macromolecular organization of complex layer systems in PLLA spherulites. The use of linearly polarized IR excitation, combined with a rapid computational algorithm applied to two nonparallel absorption bands, allowed tracing different paths of spherulite formation in PLLA/PEG films depending on the crystallization conditions. The plasticizer facilitated polymer crystallization but also caused disruption of molecular organization and a second crystallization, leading to lamellae branching. High-resolution O-PTIR microscopy, independent of the IR diffraction limit, does not require time-consuming sample preparation and, in combination with 3D orientation determination, is an excellent tool in studies on structural changes and morphology-property relationships in biology and materials science.