Natural and synthetic polymers are a versatile platform for developing biomaterials in the biomedical and environmental fields. Natural polymers are organic compounds that are found in nature. The most common natural polymers include polysaccharides, such as alginate, hyaluronic acid, and starch, proteins, e.g., collagen, silk, and fibrin, and bacterial polyesters. Natural polymers have already been applied in numerous sectors, such as carriers for drug delivery, tissue engineering, stem cell morphogenesis, wound healing, regenerative medicine, food packaging, etc. Various synthetic polymers, including poly(lactic acid), poly(acrylic acid), poly(vinyl alcohol), polyethylene glycol, etc., are biocompatible and biodegradable; therefore, they are studied and applied in controlled drug release systems, nano-carriers, tissue engineering, dispersion of bacterial biofilms, gene delivery systems, bio-ink in 3D-printing, textiles in medicine, agriculture, heavy metals removal, and food packaging. In the following review, recent advancements in polymer chemistry, which enable the imparting of specific biomedical functions of polymers, will be discussed in detail, including antiviral, anticancer, and antimicrobial activities. This work contains the authors’ experimental contributions to biomedical and environmental polymer applications. This review is a vast overview of natural and synthetic polymers used in biomedical and environmental fields, polymer synthesis, and isolation methods, critically assessessing their advantages, limitations, and prospects.

This review describes the enhanced classification of polyphenols into flavonoids, lignans, phenolic acids, stilbenes, and tannins. Its focus is the natural sources of polyphenols and an in-depth discussion of their antibacterial, antifungal, and antiviral activity. Besides a broad literature overview, this paper contains authors’ experimental data according to some daily consumed vegetables such as tomatoes, different varieties of onion, garlic, parsley, and cayenne pepper and the probable relation of these activities to polyphenols. The isolation of polyphenols via conventional and ultrasonic, pressurized liquids and pulse-field extractions, as well as their methods for detection and determination, are interpreted as well. The main mechanisms by which polyphenols inhibit the growth of bacteria, fungi, and viruses, such as protein synthesis, cell membrane destabilization, and ROS production induction, are in focus. Data on polyphenol concentrations and their respective MIC or the inhibition zone diameters of different bacterial and fungal species and suppressing viral replication are depicted. The toxicity of polyphenols in vitro, ex vivo, and in vivo towards microorganisms and human/animal cells, and the safety of the polyphenols applied in clinical and industrial applications are expanded. This review also characterizes the antimicrobial effects of some chemically synthesized polyphenol derivatives. Biotechnological advances are also reported, especially the entrapment of polyphenols in biocompatible nanoparticles to enhance their bioavailability and efficacy. Polyphenols are promising for exploring molecules’ novel antimicrobial substances and paving the path for effective novel antimicrobial agents’ discovery, taking into consideration their positives and negatives.

Lead (Pb) is a non-essential, toxic heavy metal with no known biological function that has caused widespread environmental contamination throughout human history. Pb toxicity represents one of the most persistent environmental health challenges, with no safe exposure threshold identified. The metal demonstrates remarkable persistence in biological systems, with approximately 90% of it stored in bone tissue for decades, mimicking calcium due to its similar ionic properties. Contemporary contamination primarily stems from mining activities, battery manufacturing, electronic waste recycling, and deteriorating infrastructure. Pb enters organisms through multiple pathways and causes severe health impacts across all biological systems, with particularly devastating neurodevelopmental and bone effects in children and cardiovascular and reproductive consequences in adults. On a molecular level, Pb disrupts cellular processes through ion mimicry, replacing essential metals in enzymes and proteins and leading to mitochondrial dysfunction, oxidative stress, DNA damage, and epigenetic modifications. This review examines the sources of Pb pollution and its toxicological impacts on bacteria, fungi, plants, animals, and humans. It explores the molecular mechanisms underlying these effects, including neuroinflammation, genotoxicity, and cell death pathways. The paper considers current approaches for Pb removal from contaminated environments and therapeutic interventions for Pb poisoning.

Cadmium (Cd) is a toxic metal primarily found as a by-product of zinc production. Cd was a proven carcinogen, and exposure to this metal has been linked to various adverse health effects, which were first reported in the mid-19th century and thoroughly investigated by the 20th century. The toxicokinetics and dynamics of Cd reveal its propensity for long biological retention and predominant storage in soft tissues. Until the 1950s, Cd pollution was caused by industrial activities, whereas nowadays, the main source is phosphate fertilizers, which strongly contaminate soil and water and affect human health and ecosystems. Cd enters the human body mainly through ingestion and inhalation, with food and tobacco smoke being the primary sources. It accumulates in various organs, particularly the kidney and liver, and is known to cause severe health problems, including renal dysfunction, bone diseases, cardiovascular problems, and many others. On a cellular level, Cd disrupts numerous biological processes, inducing oxidative stress generation and DNA damage. This comprehensive review explores Cd pollution, accumulation, distribution, and biological impacts on bacteria, fungi, edible mushrooms, plants, animals, and humans on a molecular level. Molecular aspects of carcinogenesis, apoptosis, autophagy, specific gene expression, stress protein synthesis, and ROS formation caused by Cd were discussed as well. This paper also summarizes how Cd is removed from contaminated environments and the human body.

Antimicrobial peptides (AMPs) are short, usually cationic peptides with an amphiphilic structure, which allows them to easily bind and interact with the cellular membranes of viruses, bacteria, fungi, and other pathogens. Bacterial AMPs, or bacteriocins, can be produced from Gram-negative and Gram-positive bacteria via ribosomal synthesis to eliminate competing organisms. Bacterial AMPs are vital in addressing the increasing antibiotic resistance of various pathogens, potentially serving as an alternative to ineffective antibiotics. Bacteriocins have a narrow spectrum of action, making them highly specific antibacterial compounds that target particular bacterial pathogens. This review covers the two main groups of bacteriocins produced by Gram-negative and Gram-positive bacteria, their modes of action, classification, sources of positive effects they can play on the human body, and their limitations and future perspectives as an alternative to antibiotics.

Antimicrobial peptides (AMPs) are usually made up of fewer than 100 amino acid residues. They are found in many living organisms and are an important factor in those organisms’ innate immune systems. AMPs can be extracted from various living sources, including bacteria, plants, animals, and even humans. They are usually cationic peptides with an amphiphilic structure, which allows them to easily bind and interact with the cellular membranes of viruses, bacteria, fungi, and other pathogens. They can act against both Gram-negative and Gram-positive pathogens and have various modes of action against them. Some attack the pathogens’ membranes, while others target their intracellular organelles, as well as their nucleic acids, proteins, and metabolic pathways. A crucial area of AMP use is related to their ability to help with emerging antibiotic resistance: some AMPs are active against resistant strains and are susceptible to peptide engineering. This review considers AMPs from three key sources—plants, animals, and humans—as well as their modes of action and some AMP sequences.