Removing antibiotics from wastewater with nano-bioadsorbents

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​​​​​​​A recent article published in the journal Scientific reports discussed the removal of the antibiotic azithromycin (Azr) from contaminated wastewater using hematite nanoparticles (α-HNP), which were bioengineered from a perennial medicinal plantEchinacea purpurée.

Study: Azithromycin-Based Pharmaceutical Wastewater Management and Charged Synergistic Biocompatible Approaches [email protected] nanoparticles. Image Credit: Bukhta Yurii/Shutterstock.com

Adsorption studies revealed the ability to remove Azr from α-HNPs in contaminated pharmaceutical wastewater. Moreover, parameters such as adsorption kinetics, isotherm and thermodynamics were studied to understand the process of Azr adsorption on the surface of α-HNPs.

Anticancer, antibacterial and antiviral properties of [email protected]α-HNPs were evaluated and the results revealed a better synergistic effect of Azr@α-HNP nanosystems against Gram-positive vs. Gram-negative bacteria. Additionally, the half-maximal inhibitory concentration (IC50) of Azr@α-HNPs were measured to assess their cytotoxic effect against HepG2, MCF7 and HCT116 cell lines, and the results revealed IC50 concentrations of 81.7 (HepG2), 78.1 (MCF7) and 93.4 (HCT116) micrograms per milliliter, respectively.

Thermodynamic studies confirmed that the adsorption of Azr on α-HNPs occurs via a spontaneous endothermic chemisorption process. In addition, the antiviral activity of [email protected]The α-HNP nanosystem against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) showed a therapeutic safety index of 25.4, suggesting its promising antiviral activity.

Nanomaterials for wastewater treatment

Macrolide (Azr) and Cephalosporin (Cephalosporin) Antibioticsceftriaxone and cefixime) are used in the treatment of cancerous and viral diseases. The unique physicochemical properties of nanomaterials provide advantages in the design of nanocarriers to efficiently transport various drugs inside a biological system. Thus, loading antibiotics into biocompatible nanomaterials could lead to efficient drug delivery systems.

The increasing demand for macrolide and cephalosporin antibiotics has led to their production in large quantities. Consequently, wastewater from pharmaceutical factories and hospitals contaminated with antibiotics pollutes the aquatic environment by entering water bodies. In addition, the excessive presence of antibiotics in the human body can cause renal tubular necrosis and induce antibiotic resistance.

Azr is a semi-synthetic macrolide antibiotic derived from erythromycin. It is lipophilic with limited water solubility and has an oral bioavailability of 37% after ingestion. Azr used as an antibacterial agent has a broad spectrum of antibacterial activity against Gram-positive and Gram-negative microorganisms. Additionally, the nitrogen-based ring systems in the chemical structure of Azr contribute significantly to its microbiological, pharmacokinetic, and chemical properties.

Removal of Azr is possible via physico-chemical methods such as advanced oxidation using ozone and photodegradation process. Adsorption is a cost effective and easy process with high performance efficiency and does not present the risk of producing highly toxic by-products. It is one of the most effective and safest strategies for removing antibiotics from aqueous environments.

Earlier reports mentioned the use of iron oxide nanoparticles in water treatment techniques. Iron oxide offers desirable characteristics such as high adsorption capacity of organic pollutants, large surface area and magnetization capacity, favorable for water treatment techniques.

In the present study, researchers used α-HNP-based nano-adsorbents to assess remediation and removal of the antibiotic Azr via adsorption technology. This study discussed the quadruple use of α-HNPs: first, as a bioadsorbent to remove the antibiotic Azr present in wastewater from pharmaceutical factories; second, using Azr@α-HNPs as an antibacterial agent against Gram-positive and Gram-negative bacteria; third, compare the efficiencies of Azr@α-HNPs and α-HNPs alone as anticancer agents; and finally, looking at the effectiveness of Azr@α-HNPs as nanomedicines against the coronavirus.

Transmission electron microscope (TEM) images revealed that the average particle size of α-HNPs and [email protected] were 27.8 ± 7.7 and 38.1 ± 9.3 nanometers, respectively, and their median sizes were 25.9 and 39.2 nanometers, respectively. The smallest and largest particle sizes of α-HNPs and [email protected] were 17.7 and 16.4 nanometers and 49 and 50.5 nanometers respectively.

The experimental results of the adsorption study revealed that a pH of 10, a dose of 150 milligrams of α-HNP and a concentration of 400 milligrams per liter of Azr, and a temperature of 293 kelvin were the conditions optimal for efficient adsorption of Azr on α-PNH. Moreover, the thermodynamic study revealed that the adsorption of Azr on α-HNPs occurs via a spontaneous endothermic chemisorption process and follows second-order kinetics.

Conclusion

In conclusion, the researchers of the present study aimed to use biosynthesized α-HNPs as a bioadsorbent of Azr found in contaminated pharmaceutical wastewater. Adsorption studies found Langmuir to be the appropriate isothermal model with a correlation coefficient R2 of 0.9992 and the maximum adsorption capacity was 114.05 milligrams of adsorbate per gram of contaminant (mg/g).

The results revealed that α-HNP based nanobioadsorbent was a promising agent for removing Azr from contaminated wastewater. Azr@α-HNPs have served as versatile nanosystems with biomedical applications such as anticancer, antiviral, and antibacterial agents. Antibacterial studies have shown a high synergistic impact of Azr@α-HNP, especially against Gram-positive bacteria.

Additionally, Azr@α-HNPs showed anticancer effects on HepG2, MCF7, and HCT116 cell lines, and its IC50 was comparatively lower than α-HNP alone against the same cell lines. The present work is the first study that revealed the use of Azr@α-HNP as an antiviral agent against SARS-CoV-2.

Reference​​​​​​​

Al-Hakkani, MF, Gouda, GA, Hassan, SHA, Mohamed, MMA., Nagiub, AM. (2022) Environmental Management of Azithromycin Pharmaceutical Wastewater and Biocompatible Synergistic Approaches to [email protected] nanoparticles. Scientific representativeorts. https://doi.org/10.1038/s41598-022-14997-y

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