Nanoparticles are intensely studied because of their importance in diverse fields of biotechnology, especially in medicine. This paper highlights that waste bark can be a cheap source of biocompounds, with high recovery and functionalization potential in nanoparticle synthesis. Due to their biocompatibility and activity as antioxidant, antimicrobial, and anticancer agents, the green synthesis of metallic nanoparticles is of great importance. This review aims to bring together the diversity of synthesized metallic nanoparticles mediated by bark extracts obtained from different woody vascular plants, the phytoconstituents responsible for the reduction of metal salts, and the activity of metallic nanoparticles as diverse agents in combating the microbial, oxidant, and cancer activity. The literature data highlight the fact that metallic nanoparticles obtained from natural compounds are proven reducing agents with multiple activities. Thus, the activity of natural components in environmental protection and human health is confirmed.

Biosynthesized silver nanoparticles (AgNPs) are widely used in Pharmacy and Medicine. In particular, AgNPs synthesized and mediated by plant extracts have shown topossess several biological activities. In the present study, AgNPs were synthesized using Picea abies L. stem bark extract as reducing agent. Factors, such as metal ion solution, pH, and time, which play a role in the AgNPs synthesis, were assessed. The synthesized AgNPs were characterized by Ultraviolet-Visible Spectrometry, Fourier transform infrared spectroscopy, and Transmission Electron Microscopy (TEM). Further, the study has been extended to evaluate the antimicrobial and antioxidant activity of AgNPs. The broad peak obtained at 411–475 nm (UV-Vis spectroscopy), and the color change pattern, confirmed the synthesis of AgNPs. TEM results showed spherical or rarely polygonal AgNPs with an average size of 44 nm at pH = 9. The AgNPs showed antioxidant activity and antibacterial effect against human pathogenic Gram-positive and Gram-negative bacteria. The results show that spruce bark extract is suitable for obtaining AgNPs, with antibacterial and antioxidant activity.

Green synthesis is one of the rapid and best ways for silver nanoparticles (AgNP) synthesis. In the present study, synthesis and bioactivity of AgNPs has been demonstrated using water beech (Fagus sylvatica L.) bark extract. The physical and chemical factors such as time, metal ion solution, and pH, which play a vital role in the AgNPs synthesis, were assessed. The AgNPs were characterized by ultraviolet-visible (UV-Vis) spectrometry, Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). Antioxidant and antimicrobial activity of the obtained AgNPs was evaluated. AgNPs were characterized by color change pattern, and the broad peak obtained at 420–475 nm with UV-Vis confirmed the synthesis of AgNPs. FT-IR results confirmed that phenols and proteins of beech bark extract are mainly responsible for capping and stabilization of synthesized AgNPs. TEM micrographs showed spherical or rarely polygonal and triangular particles with an average size of 32 nm at pH = 9, and 62 nm at pH = 4. Furthermore, synthesized AgNPs were found to exhibit antioxidant activity and have antibacterial effect against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. These results indicate that bark extract of F. sylvatica L. is suitable for synthesizing stable AgNPs, which act as an excellent antimicrobial agent.

The main disadvantage of the implants is the associated infections. Therefore, in the long term, the possibility of improving the antibacterial capacity of different types of implants (dental, orthopedic) is being researched. The severity of the problem lies in the increasing bacterial resistance and finding appropriate alternative treatments for infectious diseases, which is an important research field nowadays. The purpose of this review is to draw a parallel between different studies analyzing the antibacterial activity and mechanism of silver nanoparticles (NP Ag) deposited on the titanium nanotubes (NTT), as well as the analysis of the NP Ag toxicity. This review also provides an overview of the synthesis and characterization of TiO₂-derived nanotubes (NT). Thus, the analysis aims to present the existing knowledge to better understand the NP Ag implants benefits and their antibacterial activity.

Processing wood leads to the accumulation of considerable amounts of forest waste, such as branches, leaves and especially bark. These byproducts can be exploited for their high content of biomolecules. Our aim was to histo-anatomically and phytochemically characterize the older oak bark and evaluate the potential biological activities. After the histo-anatomical characterization and processing the plant material, the aqueous and hydroalcoholic extracts were obtained using microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE). After the quantification of the total polyphenol content (TPC) and the total tannins content (TTC), the bark extracts were evaluated for antioxidant, antimicrobial and enzyme inhibitory activity. In the transverse section, the rhytidome (the succession of periderms) and the dead secondary phloem can be observed. The results of the polyphenol content of the oak bark extracts show that the hydroethanolic oak bark obtained using MAE has the highest absolute value of the TPC (347.74 mg/g). In comparison with the extracts obtained using UAE, the bark extracts obtained using MAE showed a significantly higher TPC. The greatest antioxidant and antibacterial activity were also recorded for the tested extracts. For gram-positive bacteria, the MBC values ranged from 0.3 (S. aureus) to 5 mg/mL and the oak bark extract obtained using MAE showed good activity against C. krusei (MIC—2.5 mg/mL). Among the assayed enzyme inhibitory activities, the extracts showed a significant antidiabetic effect in vitro with the highest activity corresponding to an IC₅₀ of 3.88 µg/mL. The older oak bark represents a potential source of compounds with antibacterial, antioxidant or antidiabetic activity, which can be exploited through the biorefining processes.