IIT Bombay Develops Single-Step Method To Make High-Performance Nanoparticle-Coated Microfibres
Microfibre-based water filters are a good option for household water filtering as they can filter out germs and pollutants, are durable, and offer a high retention capacity. Adding an appropriate nanoparticle coating can make the microfibres useful for diverse purposes, such as absorbing toxic heavy metals and dyes. Choose a suitable nanoparticle coating, and they can make ideal wound dressings as well.
In the conventional method to coat microfibres, previously spun threads are dipped into the nanoparticle dispersion. The method needs bulky equipment, is tedious, and produces low-performing microfibres. Since the flow of nanoparticles cannot be controlled, nanoparticles form clumps on the microfibre, leaving the rest bare. The uneven nanoparticle coating allows sediment and particulates to pass through the filters easily, making them inefficient.
Read also: JEE Main 2026 Registrations Likely To Start Next Month
Researchers from the Department of Chemical Engineering at the Indian Institute of Technology Bombay (IIT Bombay), jointly led by Prof. Venkat Gundabala and Prof. Rajdip Bandyopadhyaya, have devised a microfluidic technique to produce high-performance nanoparticle-coated microfibres in a single step. In their recent study, the researchers demonstrated that the single-step method can create microfibres uniformly coated with nanoparticles, such as Magnesium Oxide (MgO) nanoparticles synthesised by them, and used in this work. The researchers then also tested these MgO-coated microfibres for their performance in filtering heavy metals, such as lead, cadmium and arsenic, from water.
Their setup uses two glass tubes: the inner 0.7 mm diameter capillary tube, in which the polymer, polyvinylidene fluoride (PVDF), dissolved in Dimethylacetamide (DMAc) solvent, is pushed using a syringe pump. Simultaneously, in the outer tube with a cross-section of 1 mm square, another syringe pump adds the nanoparticle dispersion. The researchers regulated the concentration and flow of polymer and nanoparticle dispersion within the glass tubes, ensuring fibre formation and uniform coating at once.
The glass tubes act as a microfluidic device, allowing precise control over the liquids. As the polymer exits the capillary tube as a jet, it comes in contact with the water in the aqueous nanoparticle dispersion co-flowing with the jet. The DMAc solvent disperses into water, converting the liquid polymer jet into a solid fibre. This single-step method allows the formation of microfibres and coats them with the desired nanoparticles at once.
“Magnesium oxide (MgO) nanoparticles stick to the fibre surface through favourable interactions – with positively charged MgO having a strong attraction to the negatively charged PVDF polymer. Further, the water carrying the nanoparticles flows around the polymer jet throughout, with the nanoparticles continuously and uniformly surrounding it; this is key to achieving uniform nanoparticle coating on the fibre,” explains Prof. Gundabala.
Read also: A First, AI Generates Bacteria-Killing Genome, Paving Way For Medical Breakthroughs: Report
The researchers tested the MgO-coated PVDF fibres for removing heavy metals from water samples with known concentrations of lead, cadmium and arsenic. When water passes through the filter, nanoparticles trap metals through electrostatic attraction or ion exchange, allowing clean water to pass through. The results show the potential for scaling up this method for treating household water and groundwater.
“Nanomaterial-coated fibres can be packed into filter cartridges or columns that can be used in under-sink, whole-house filtration units, or in portable water purification units and modular filters,” highlights Prof. Bandyopadhyaya.
The microfibres’ applications extend beyond water purification. Different types of fibres, such as quantum dot-coated (small semiconductor particle) fibres, can be used as sensors to detect pollutants. Titanium oxide, copper, or silver nanoparticles have excellent antibacterial properties and can be used in healing bandages and food packaging. Fibres coated with drugs can be used to deliver medicine to specific areas inside the body, promoting tissue growth. Nanoparticles can also be used to remove microplastics and other organic pollutants.
“When fibres are coated with nanomaterials, such as magnetic iron oxide nanoparticles, or graphene oxide rods, they are efficient in entrapping microplastics. Similarly, fibres coated with imine-functionalised silica nanoparticles, nickel oxide or zinc oxide nanoparticles are excellent for entrapping organic pollutants,” signs off Prof. Gundabala.
