A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO) based sensors for the selective and sensitive detection of various environmental pollutants is presented.

Pesticides and organic waste constitute a group of environmental pollutants that are widely distributed in our environment due to various human activities. Adsorptive removal and photocatalytic degradation of these pollutants from water have emerged as energy and cost-effective technologies. However, advanced oxidation technologies are gaining attention as an effective method for wastewater treatment capable of degrading a diverse spectrum of organic contaminants. Photocatalysis is a promising advanced oxidation technology to alleviate water pollution problems. Titanium dioxide (TiO₂) is the most popular photocatalyst due to its low cost, nontoxicity, high oxidizing abilities, and easy immobilization on various surfaces. The current review aims to highlight recent advancements in photocatalytic degradation of pesticides and major organic pollutants using TiO₂-based photocatalysts. Indeed, most of the methods, which employed potent catalysts, showed and exhibited successful degradation of the pesticides under various conditions. We believe this topic of research is extremely vital and will continue to grow in recent years, reaching ultimate desirable results and find more applications in different fields of study.

In the last decade, gold and silver nanomaterials have received considerable attention due to their attractive electronic and chemical properties and their potential applications in the development of new technologies. Recent advances in the study of various gold and silver nanomaterials have led to their utilization in a number of very important applications including biosensing, diagnostic imaging, and cancer diagnosis and therapy. This review surveys the various synthetic methods of gold and silver nanomaterials. Recent experimental studies focusing on the use of gold and silver nanomaterials in catalysis, food industry, and environmental conservation are also reviewed. This review also highlights the advantages of gold and silver nanomaterials in the development of fluorescence biosensors, glucose biosensors, nucleic acids-based biosensors, and protein-based biosensors. Moreover, the potent in vitro and in vivo anti-microbial and cyto-genotoxic effects of various gold and silver nanomaterials are underlined. Finally, recent advances in the employment of gold and silver nanomaterials as effective drug delivery vehicles and promising cancer therapeutic agents are summarized. Despite their use in remediating numerous medical and health-related conditions, the efficacy and safety of many gold and silver nanomaterials is still under some scrutiny. Needless to say, researchers are facing many challenges and obstacles in their ample attempts to synthesize nanomaterials that are relatively easy to design, inexpensive to fabricate, and effective in treating various diseases, but at the same time display a very low, if any, toxicity to the body. Future investigations should aim at overcoming such challenges in an attempt to design nanomaterials that will prove to be useful in diagnosing and treating life-threatening diseases while ensuring a high degree of efficacy and safety.