Muthupandian Ashokkumar's research while affiliated with Victoria University Melbourne and other places

Publications (501)

Article
Power ultrasonics (> 100 kHz), through acoustic cavitation, efficiently splits water to generate reactive oxygen species (ROS: ·OH, O, HO2·, O3 and H2O2). As a result, water sonolysis is considered as an alternative advanced oxidation process for water treatment. In this process, the type of dissolved gases plays a crucial role in controlling the r...
Article
Metal-free polymeric graphitic carbon nitride (CN) materials are robust and stable visible-light-driven photocatalysts that have recently piqued interest in photocatalytic applications. Its photocatalytic performance is restricted remarkably due to moderate oxidation ability and fast charge carrier recombination rate. To address these issues, we en...
Article
In this study, quantitative monitoring of low-frequency (20 kHz) and high-frequency (355 kHz) ultrasound-induced inactivation of Kunitz (KTI) and Bowman-Birk inhibitor (BBI) was achieved, and its consistency with a traditional TI activity assay was verified. Four key factors including TI concentration, ultrasonic frequency, power density and pH val...
Article
Nisin, a peptide used as a natural food preservative, is employed in this work for the development of a novel nanocarrier system. Stable and uniform nisin-shelled nanoemulsions (NSNE) with a diameter of 100±20nm were successfully prepared using 20 kHz flow-through ultrasonication technique. The NSNE showed limited toxicity, high bactericidal activi...
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The global energy crisis is increasing the demand for innovative materials with high purity and functionality for the development of clean energy production and storage. The development of novel photo- and electrocatalysts significantly depends on synthetic techniques that facilitate the production of tailored advanced nanomaterials. The emerging u...
Article
An alternative semi-empirical technique is developed to determine the number density of active cavitation bubbles (N) formed in sonicated solutions. This was achieved by relating the acoustic power supplied to the solution (i.e. determined experimentally) to the released heat by a single bubble. The energy dissipation via heat exchange is obtained...
Article
In the last decades, great interest has been focused on developing innovative, efficient and eco-friendly methods for the reduction of carbon dioxide (CO2). The use of ultrasound (sonochemistry) has appeared as one of these techniques, thanks to its operational simplicity (working at ambient conditions), safety and being environ- mentally benign...
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Ultrasonic processing has a great potential to transform waste from the food and agriculture industry into value-added products. In this review article, we discuss the use of ultrasound for the valorisation of food and agricultural waste. Ultrasonic processing is considered a green technology as compared to the conventional chemical extraction/proc...
Article
A comprehensive numerical investigation was conducted to analyze the effect of ultrasound frequency (213-1000 kHz), ultrasonic intensity (0.7-1.5 W/cm 2) and medium temperature (293.15-333.15 K) on the production of hydrogen from methanol decomposition inside acoustic bubbles (methanol sono-conversion). The adopted model was firstly compared with s...
Article
Confined sono-polymerization is developed to prepare poly(ethylene glycol) nanoparticles within water-in-oil microemulsion, followed by post-functionalization with a bispecific antibody (anti HER2 and anti PEG) for targeted delivery of photosensitizers (i.e., indocyanine green). The nanoparticles could specifically target to breast cancer cells (i....
Article
Critical bone defects with a sluggish rate of auto-osteoconduction and imperfect reconstruction are motivators for the development of an alternate innovative approach for the regeneration of bone. Tissue engineering for bone regeneration signifies an advanced way to overcome this problem by creating an additional bone tissue substitute. Among diffe...
Article
The present study combines, for the first time, experimental degradation findings and numerical simulation results of CCl4 sonochemistry for (i) understanding the right mechanism by which CCl4 improves Safranin O (SO) sono-bleaching (1.7 MHz, 15 W) and (ii) stating the impact of operational conditions on reactive species dis- tribution toward the...
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This article reports on the ultrasound-assisted acid hydrolysis for the synthesis and evaluation of starch nanoparticles (SNP) as nanofillers to improve the physical, mechanical, thermal, and barrier properties of polyurethane (PU) films. During the ultrasonic irradiation, dropwise addition of 0.25 mol L⁻¹ H2SO4 was carried out to the starch disper...
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Amyloid crystals, a form of ordered protein aggregates documented relatively recently, have not been studied as extensively as amyloid fibres. This study investigates the formation of amyloid crystals with low frequency ultrasound (20 kHz) using β-lactoglobulin, as a model protein for amyloid synthesis. Acoustic cavitation generates localised zones...
Article
The current study reports on the preparation of perovskite-type CeNiO3 nanostructures as a sonophotocatalyst via a facile hydrothermal approach followed by annealing at 800 °C. The CeNiO3 catalyst was characterized by various physicochemical techniques to comprehend the crystallinity, microstructure, and morphological features of perovskite nanostr...
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Transforming small-molecule antibiotics into carrier-free nanoantibiotics represents an opportunity for developing new multifunctional therapeutic agents. In this study, we demonstrate that acoustic cavitation produced by high-frequency ultrasound transforms the antibiotic doxycycline into carrier-free nanobiotics. Upon sonication for 1 h at 10-15...
Article
Gel-like emulsions formed with colloidal particles have attracted great attention in various research fields, with studies on food applications surging in an effort to discover new food-grade particle stabilisers that can replace chemical emulsifiers and stabilisers. Turbulence-induced emulsion gels (TIEG) have recently been reported as a novel mea...
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We report on the fabrication of lysozyme microspheres (LyMs) incorporated with gold nanorods (NRs) as a distinctive approach for the encapsulation and release of an anticancer drug, 5-Fluorouracil (5-FU). LyMs with an average size of 4.0±1.0 µm were prepared by a sonochemical method and characterized using scanning electron microscopy (SEM), transm...
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Reconfiguring the structure and selectivity of existing chemotherapeutics represents an opportunity for developing novel tumor‐selective drugs. Here; we demonstrate; as a proof‐of‐concept; the use of high‐frequency sound waves to transform the non‐selective anthracycline doxorubicin into a tumor selective drug molecule. The transformed drug self‐ag...
Article
Graphitic carbon nitride (CN) is recognized as a promising photocatalyst for energy and environmental remediation. However, challenges persist due to limited CN surface-active sites and poor electronic properties. To overcome such challenges, we have synthesized Carbon Quantum Dots decorated Boron-doped Exfoliated CN ([email protected]) via ultraso...
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Ultrasound induced cavitation (acoustic cavitation) process is found useful in various applications. Scientists from various disciplines have been exploring the fundamental aspects of acoustic cavitation processes over several decades. It is well documented that extreme localised temperature and pressure conditions are generated when a cavitation b...
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To acquire substantial electrochemical signals of guanine-GUA and adenine-ADE present in deoxyribonucleic acid-DNA, it is critical to investigate innovative electrode materials and their interfaces. In this study, gold-loaded boron-doped graphene quantum dots ([email protected]) interface was prepared via ultrasound-aided reduction method for monit...
Article
For the past few decades, industrialization has made a huge environmental hazard to the world with its waste. The approach of waste to wealth in the recent era has made many Eco-economical suggestions for the industries. The valuable products in biorefinery aspects of the eco-economical suggestions include; energy products, high-value drugs and nov...
Chapter
Photocatalytic hydrogen production is a process that deals with the utilization of solar energy into green chemical fuel via photocatalysis phenomena using a novel photocatalyst. Over the past few decades, significant amount of research work has been carried out to enhance the production of hydrogen using various semiconductor materials. Graphitic...
Chapter
This Chapter provides on an overview of recent studies on the improvement of heat transfer (HT) properties on heat exchangers utilizing nanofluids in binary sections. The first section is concerned with the numerical investigations on the Nusselt number, friction factor and pressure drop measurement reported in different studies on different heat e...
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The present paper introduces a novel semi-empirical technique for the determination of active bubbles’ number in sonicated solutions. This method links the chemistry of a single bubble to that taking place over the whole sonochemical reactor (solution). The probe compound is CCl4, where its eliminated amount within a single bubble (though pyrolysis...
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In this work, oil-in-water emulsions stabilised by milk protein concentrate (MPC70) were investigated. The MPC70 concentration was kept constant at 5% (close to the protein content found in skim milk) and the oil volume fraction was varied from 20 to 65%. Sonication was performed at 20 kHz and at a constant power of 14.4 W for a total emulsion volu...
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Yarrowia lipolytica is used as a model in this study to screen the potential candidates for inflating the innate lipid content of the cell. This study focuses on reducing the lipid degradation that occurs by the β-oxidation process and discursively increasing the innate lipid content. Acyl-CoA oxidase-1, the primary and initial enzyme involved in t...
Article
Acoustic cavitation (or the formation of bubbles using acoustic or ultrasound-based devices) has been extensively exploited for biological applications in the form of bioprocessing and drug delivery/uptake. However, the governing parameters behind the several physical effects induced by cavitation are generally lacking in quantity in terms of suita...
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Emulsion gels have a wide range of applications. We report on a facile and versatile method to produce stable emulsion gels with tunable rheological properties. Gel formation is triggered by subjecting a mixture containing aqueous colloidal particle (CP) suspensions and water-immiscible liquids to an intense turbulence, generated by low frequency (...
Article
Graphitic carbon nitride (g-C3N4) is an emerging metal-free photocatalyst, however, engineering the photocatalytic efficiency for the effective degradation of hazardous molecules is still challenging. An unstable and low bandgap CuWO4 was composited with g-C3N4 to achieve synergistic benefits of tuning the visible light responsiveness and stability...
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Ultrasonically synthesized core-shell microcapsules can be made of synthetic polymers or natural biopolymers, such as proteins and polysaccharides, and have found applications in food, drug delivery and cosmetics. This study reports on the ultrasonic synthesis of microcapsules using unmodified (natural) and biodegradable glycogen nanoparticles deri...
Article
Polyphenol‐based supramolecular assembly has attracted interest for engineering a range of functional surface coatings. Herein, we report a sono‐Fenton strategy to mediate the supramolecular assembly of metal–phenolic networks (MPNs) as substrate‐independent coatings using phenol and phenyl derivatives as building blocks. The assembly process is in...
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Polyphenol‐based supramolecular assembly has attracted interest for engineering a range of functional surface coatings. Herein, we report a sono‐Fenton strategy to mediate the supramolecular assembly of metal–phenolic networks (MPNs) as substrate‐independent coatings using phenol and phenyl derivatives as building blocks. The assembly process is in...
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The development of simple, green, reproducible, and scalable approaches for synthesizing nanoparticles from biomolecules is important to advance nanomaterials towards therapeutic applications. Microreactors generated by high frequency ultrasound provide a one pot-platform to alter the physiochemical properties and stability of various types of biom...
Presentation
Wet lipid extraction is favoured over lipid extraction from dried microalgae due to the high energy costs associated with drying. Further, biphasic lipid extraction from wet paste using non-polar solvents is preferable to using water-miscible that require energy-intensive distillation to separate from water. However, it has been found that cell rup...
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Multi-walled carbon nanotubes (MWCNTs) were decorated with palladium nanoparticles (Pd NPs) by laser-ablation of a physical mixture of MWCNTs and Pd NPs without using any reducing agent. The morphology and composition of MWCNT/Pd were analysed by complementary techniques involving Fourier transform infrared spectrometry, transmission electron micro...
Article
Photocatalytic treatment of organic pollutants present in wastewater using semiconductor nanomaterials under light irradiation is one of the efficient advanced oxidation processes. Stable metal oxide (e.g.x, TiO2) based semiconductor photocatalytic systems have been mainly investigated for this purpose. Nevertheless, their large band gap (∼3.2 eV)...
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This study was aimed at providing new insights on the response of bacterial cell membranes to ultrasound exposure. Escherichia coli (E. coli) O157:H7 cells were exposed to different ultrasound treatments (power intensities of 64, 191, 372, and 573 W/cm², frequency of 20 kHz, pulsed mode of 2 sec: 2 sec) and the dynamic changes in cell viability wit...
Article
Three different proteinaceous biopolymers, namely, egg white protein (EWP), soy protein isolate (SPI) and corn protein isolate (CPI) were used as protective shell materials to encapsulate micronutrients via an ultrasonic encapsulation technique. It was found that the physicochemical properties of the three protein-based matrices, including surface/...
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MgTi2O5 (magnesium dititanate) nanoparticles were prepared by a simple hydrothermal assisted post-annealing method and characterized with various analytical techniques. The catalytic properties (sonocatalytic, photocatalytic and sonophotocatalytic activity) were evaluated using the degradation of triphenylmethane dyes (crystal violet, basic fuchsin...
Article
In this study, the effect of ultrasonic frequency and power on the inactivation of soy trypsin inhibitors was investigated to explore the ultrasound-induced inactivation mechanism. It was observed that 20 kHz and 355 kHz ultrasound have better inactivation efficiency than 1056 kHz. First-order rate constants for the inactivation process were obtain...
Article
In this study, the impact of ozonation abetted with the citric acid pretreatment (OZCAP) method on fruit waste was investigated for ameliorating hydrogen production. Initially, the ozonation pretreatment (OZP) method was performed by varying ozone (O 3 ) dosage and disintegration time. At optimized conditions (O 3 dosage (0.04 g/g suspended solid;...
Article
Double emulsion (W1/O/W2) microcapsules containing probiotic lactic acid bacteria (LAB) and bioactive γ-aminobutyric acid (GABA) were prepared by two-step ultrasonication using dextran and whey protein as encapsulating materials. The formulation and ultrasound parameters were refined to optimise the size of the W1/O droplets and outer microcapsules...
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Polydopamine (PDA) coating of surfaces is a versatile strategy to fabricate functional films on various substrates, which typically requires oxygen and alkaline pH. Overcoming such limitations may enhance the versatility of this technique. Herein, we develop a simple and green sonochemical process for PDA coatings, which overcomes the limitations o...
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We report the microencapsulation of oil soluble vitamins (A, D and E) using a one pot ultrasonic process using raw egg white proteins as a shell material. Green tea catechin/iron complex coating method was further developed to impart UV filtering property to the microcapsules in order to protect the encapsulated nutrients from photodegradation. The...
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A powerful experimental approach to measure the size distribution of bubbles active in sonoluminescence and/or sonochemistry is a technique based on pulsed ultrasound and sonoluminescence emission. While it is an accepted technique, it is still lacking an understanding of the effect of various experimental parameters, including the duration of the...
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Knowledge on cavitation bubble size distribution, ambient radius of bubbles is of interest for many applications that include therapeutic and diagnostic medicine. It however becomes a hard quest when increasing the ultrasonic frequency, when direct observation of bubble dynamics is no longer possible. An indirect method based on the estimation of t...
Article
Recently, different nanomaterial-based adsorbents have received greater attention for the removal of environmental pollutants, specifically heavy metals from aqueous media. In this work, we synthesized few-layered MoS2 nanosheets via a surfactant-assisted hydrothermal method and utilized them as an efficient adsorbent for the removal of mercury fro...
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The generation of cavitation-free radicals through evanescent electric field and bulk-streaming was reported when micro-volume of a liquid was subjected to 10 MHz surface acoustic waves (SAW) on a piezoelectric substrate [Rezk et al., J. Phys. Chem. Lett. 2020, 11, 4655−4661; Rezk et al., Adv. Sci. 2021, 8.1, 2001983]. In the current study, we have...
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The by-products generated from the processing of fruits and vegetables (F&V) largely are underutilized and discarded as organic waste. These organic wastes that include seeds, pulp, skin, rinds, etc., are potential sources of bioactive compounds that have health imparting benefits. The recovery of bioactive compounds from agro-waste by recycling th...
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Significant advances in various industrial processes have resulted in the discharge of toxic pollutants into the environment. Consequently, it is essential to develop efficient wastewater treatment processes to reduce water contamination and increase recycling/reuse. Photocatalytic degradation is considered as an efficient method for the degradatio...
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Alternative methods for improving traditional food processing have increased in the last decades. Additionally, the development of novel dairy products is gaining importance due to an increased consumer demand for palatable, healthy, and minimally processed products. Ultrasonic processing or sonication is a promising alternative technology in the f...
Article
The development of highly surface-active nano-sized and submicron particles with well-defined features is a promising approach in regulating various physicochemical properties of materials for different applications. A new hybrid technique involving pulsed laser irradiation and sonochemical processes for the production of Pd nanoparticles, NiPd all...
Article
Many materials have been explored as a counter electrode material to replace platinum electrode in dye-sensitized solar cells (DSSCs). In this work, CoxSy/NixSy/MoxSy composites at two different compositions, namely, CNM10, CNM25 were synthesized via hydrothermal method. The XRD, FE-SEM, and EDX analysis of the samples confirmed the formation of CN...
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Nanomaterials have found many applications due to their unique properties such as high surface-to-volume ratio, density, strength, and many more. This review focuses on the recent developments on the synthesis of nanomaterials using process intensification. The review covers the designing of microreactors, design principles, and fundamental mechani...
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Spherical shaped nano-size aluminium oxide and its hybrids with indole and indole derivatives have been synthesized using sol-gel and post grafting methods coupled with sonication (Branson Digital SonifierS-250D; 20 kHz; 40%) for the remediation of toxic metals (lead and mercury). Different spectroscopic techniques (FTIR, SEM, BET, XRD, and XPS) ha...