Ecological synthesis of functional ZnO NPs from papaya

A new technique to synthesize and characterize zinc oxide-based nanoparticles using papaya leaf extract is presented in the study submitted to the journal Materials Today: Reviews.


​​​​​​​Study: Green synthesis and characterization of ZnO nanoparticles – A new approach using Carica papaya leaf extract. Image Credit; Always AB/

Opening up new horizons with nanotechnology

Nanotechnology has seen dramatic growth in recent years due to its applications in healthcare, chemistry, and biotechnology. Developments in this field have created new vistas in nanoscience, including drug delivery, genetics, medicine, and biological sensing, with the help of the fundamental building blocks of nanotechnology, nanoparticles (NPs).

One of the many remarkable aspects of NPs is their exceptional surface/volume ratio. This property of NPs allows them to become more sensitive than ordinary bulk materials because the atoms on the outside are more energetic than the atoms in the center.

NPs can be created using various physical, biological or chemical methods. These methods include hydrothermal treatment, laser ablation, sol-gel synthesis, lithography and other physicochemical methods; however, these techniques require specialized equipment and experienced workers.

Nanotechnology – is it green?

Recent research demonstrates the relevance of metal oxide synthesis of NPs using green technology, where various metal oxides such as zinc oxide, silver oxide, nickel oxide and d others gain in importance.

Green nanotechnology is an innovative and environmentally friendly approach for the development of nanotechnology with applications in multiple fields, such as the pharmaceutical industry, biomedicine, the development of solar electric components, cosmetics and several other sectors. . The green synthesis process produces NPs that are inexpensive, non-hazardous and biodegradable.

This technique of ecological synthesis uses organic materials such as flower, leaf and root extracts, as well as microorganisms such as bacteria, fungi and algae. This use of organic substances ultimately minimizes the requirement of any toxic compounds for NP synthesis.

The power of zinc oxide

Synthesis of natural product NPs based on zinc oxide using ecologically green benign approaches has been prioritized by current researchers to avoid the use of harmful chemicals. This resulted in an environmentally friendly and non-toxic procedure that produces zinc oxide nanoparticles. These nanoparticles have remarkable antioxidant, antibacterial and anticancer properties and are therefore widely used in healthcare institutions.

At about 25 degrees Celsius, zinc oxide natural product NPs exhibit a band gap of 3.3 ev and a binding energy excitation of about 60 mev, as well as a high surface-to-volume ratio combined with excellent transparency.

Additionally, according to the United States Food and Drug Administration (USFDA), zinc oxide and other zinc compounds are generally recognized as safe materials. Due to their excellent biological stability and relatively low toxicity, zinc oxide NPs are well-studied with several potential uses in laser diodes, ultraviolet light detectors, and gas sensors, among others.

How Papaya Leaves Can Help Synthesize Zinc Oxide

In this study, the team demonstrated for the first time ever the production of zinc oxide natural product NPs in a green synthetic way using Carica papaya leaf extract and zinc acetate. .

Carica papaya is considered a therapeutic plant belonging to the Caricaceae family. This plant is also known as papaya/pawpaw. The bark, fruits, and leaves of papaya are used to treat various diseases including eczema, constipation, amenorrhea, cancer, malaria, diabetes, dengue, and syphilis, among others.

According to research, Carica papaya leaves and its fruit extracts are used as a remedy for dengue fever. The extracts work by increasing the number of platelets and red blood cells, which makes Carica papaya effective against red blood cell sickle as well.

The stem extract of the plant has been shown to have leishmanicidal and schistosomicidal properties. The extracts are rich in vitamins, flavonoids, phenols, antioxidants and proteolytic enzymes, which function as potent anticancer, antibacterial and antioxidant agents.

Study results

The team effectively accomplished the task of producing zinc oxide natural product NPs using Carica papaya plant using green synthesis. The team noted that the generated NPs were 50 nm in size with a wurtzite architecture.

It was pointed out by the team that the green synthesis process has a lower cost, is environmentally friendly and has superior qualities regarding efficiency compared to other traditional methods.

The team concluded that the leaf extract of the Carica papaya plant is a highly effective reducer in the manufacture of NPs of natural zinc oxide products with use in many areas.


Nizamuddin, S., Hymavathi, A., Yaku, G. and Kumar, U. (2022). Green synthesis and characterization of ZnO nanoparticles – A new approach using Carica papaya leaf extract. Materials Today: ReviewsAvailable at:

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