A recent review highlights the potential of using common waste materials, such as fruit peels and food waste, for the sustainable synthesis of nanoparticles, utilizing their rich natural compounds as reducing and stabilizing agents. This green chemistry approach enhances production efficiency compared to traditional methods, offering significant economic and environmental benefits by using biomass waste streams and reducing raw material costs. Challenges remain regarding consistency, long-term safety, and scaling up production. There is a need for clear regulatory guidelines and standardised toxico­logical evaluations which are improved to enable wider industrial adoption.

Using waste to synthesise nanoparticles

A recent review article showed that common waste materials, such as banana, mango or onion peels, human hair, and tea waste, can be valuable resources for the synthesis of nanoparticles.  These agricultural and food production wastes are rich in natural compounds—such as polyphenols, sugars, and proteins— that can act as reducing and stabilising agents. In addition, these compounds help convert metal ions into solid nanoparticles while preventing the particles from clumping together. This approach not only reduces the need for toxic chemicals but also saves energy. The combination of green chemistry and nanotechnology is a tangible example of the transition towards a circular economy, where waste is minimised and resources are reused.

Enhanced production efficiency

Until recently, microorganisms were often used for the natural production of nanomaterials. Interestingly, waste-derived materials usually can produce nanoparticles more quickly and with greater stability. These biomass sources offer unique advantages for nanoparticle production, making the process more efficient and cost-effective. Advanced characterisation techniques have confirmed that the nanoparticles produced have properties that are desirable for various applications, including medicine, electronics, and environmental remediation.

Versatile applications for diverse nanoparticles

Different starting materials yield different nanoparticles. For example, orange peels are used to produce antibacterial silver nanoparticles, eggshells serve as a source for calcium and iron oxide nanoparticles, and fish or shellfish waste can be transformed into carbon- or chitosan-based nanostructures. This variety opens a wide range of (potential) applications, including medicines, wound healing, environmental and water purification, food packaging, energy and catalysis.

New synthesis techniques

In addition to the classical extraction methods, microwave and ultrasonic techniques are gaining ground. These methods rapidly and uniformly heat or vibrate the biomass, accelerating nanoparticle formation while conserving energy, and ultimately yielding cleaner, more efficient, and better-controlled outcomes. The authors of the review paper emphasise that controlling parameters such as pH, temperature, and biomass composition are crucial, as even minor variations in the natural content of plant or food waste can strongly influence the shape and size of the resulting nanoparticles.

Latest scientific insights

The review not only highlights the more efficient and sustainable production of nanoparticles but also points out an improved understanding of the chemical mechanisms through which natural molecules reduce metal ions. This knowledge can be used to tailor the properties of nanoparticles depending on their intended applications. Another finding is that multifunctional nanoparticles are becoming increasingly realistic—one type can simultaneously act as antibacterial, catalytic, and environment-cleaning material.

Challenges and outlook

Despite the promising advancements, several obstacles remain. The natural variability of biomass often makes it challenging to produce nanoparticles with consistent properties. Moreover, there is still limited knowledge about their long-term toxicity and safety, since the waste-specific coating may affect the toxicity profile of the nanoparticles. The authors call for standardised production methods and test guidelines. Additionally, scaling up production to an industrial level also remains a significant hurdle, necessitating energy-efficient processes and well-defined regulations.

Reflections by RIVM

The green production of metallic nanoparticles from waste biomass is developing rapidly and offers a promising, sustainable approach to synthesising advanced materials like nanoparticles. This process transforms waste into a valuable resource for medicine, environmental technologies, and smart packaging—a prime example of how science and sustainability can mutually reinforce each other.
Although the green synthesis of nanoparticles is more sustainable and environmentally friendly than traditional chemical methods, important knowledge gaps remain. The nanoparticles produced through these sustainable approaches may not differ fundamentally from those synthesised through more conventional methods. Consequently, the existing issues surrounding their risk assessment remain, including knowledge gaps on long-term toxicity and the availability of safety testing methods. Addressing these issues is essential to valorise the potential of green nanoparticle synthesis fully.