Nature engineered diatom biosilica as drug delivery systems

Uthappa, U.T.,Brahmkhatri, Varsha,Sriram, G.,Jung, Ho-Young,Yu, Jingxian,Kurkuri, Nikita,Aminabhavi, Tejraj M.,Altalhi, Tariq,Neelgund, Gururaj M.,Kurkuri, Mahaveer D. Elsevier 2018 Journal of controlled release Vol.281 No.-

<P><B>Abstract</B></P> <P>Diatoms, unicellular photosynthetic algae covered with siliceous cell wall, are also called frustule. These are the most potential naturally available materials for the development of cost-effective drug delivery systems because of their excellent biocompatibility, high surface area, low cost and ease of surface modification. Mesoporous silica materials such as MCM–41 and SBA–15 have been extensively used in drug delivery area. Their synthesis is challenging, time consuming, requires toxic chemicals and are energy intensive, making the entire process expensive and non-viable. Therefore, it is necessary to explore alternative materials. Surprisingly, nature has provided some exciting materials called diatoms; biosilica is one such a material that can be potentially used as a drug delivery vehicle. The present review focuses on different types of diatom species used in drug delivery with respect to their structural properties, morphology, purification process and surface functionalization. In this review, recent advances along with their limitations as well as the future scope to develop them as potential drug delivery vehicles are discussed.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A comprehensive review on microbial fuel cell technologies: Processes, utilization, and advanced developments in electrodes and membranes

Palanisamy, Gowthami,Jung, Ho-Young,Sadhasivam, T.,Kurkuri, Mahaveer D.,Kim, Sang Chai,Roh, Sung-Hee Elsevier 2019 Journal of cleaner production Vol.221 No.-

<P><B>Abstract</B></P> <P>Microbial fuel cells have gained great interest as an alternative energy conversion system for generating bioenergy. As a bioelectrochemical hybrid system, microbial fuel cells involved in electricity generation and wastewater treatment including nutrients recovery with tremendous benefits such as energy saving, reduced sludge generation and energy conversion. In this review, we mainly emphasize the developments and advancements of electrode and membrane materials for increasing the microbial fuel cell performances in recent years. We reviewed and discussed the different categories of electrode (anode and cathode) materials with various structural, dimensional, compositions and integrations. Moreover, it encloses the cost-effective, biocompatible and highly stable electrode materials with improved microbial fuel cell performance. Using hetero-atom doped 3-Dimensional porous carbon with ultra-fine metal nanoparticles, a large surface area of the electrode material with different dimensional, and new core@shell structure can considerably enhance the oxygen reduction reaction performance during the microbial fuel cell operation. Following this overview, development in membrane materials such as perfluorinated polymer, hydrocarbon polymer, organic-organic hybrid polymer, organic-inorganic hybrid composite, ceramics, and biopolymer membranes are explained in detail. Based on the physical, chemical, mechanical and biocompatible properties, the hybrid composite biopolymer membrane with organic and inorganic additives are recommended as a suitable membrane candidate for increasing the ion conductivity and rectifying the biofouling issues during the long term operation. Finally, the future viewpoints in the microbial fuel cell for effective wastewater treatment process with electricity generation are suggested through various aspects and strategies to afford clean energy and environment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Detail information about the advantages, applications and challenges of MFC system. </LI> <LI> A comprehensive review of microorganism, electrodes and membranes in MFC. </LI> <LI> Prospective suggestions for the advanced developments of MFC performance. </LI> <LI> Novel structured, composite and low-cost electrode materials are suggested. </LI> <LI> Biofouling issues and oxygen cross-over can be controlled by hybrid membranes. </LI> </UL> </P>

Electro-analytical performance of bifunctional electrocatalyst materials in unitized regenerative fuel cell system

Sadhasivam, T.,Palanisamy, Gowthami,Roh, Sung-Hee,Kurkuri, Mahaveer D.,Kim, Sang Chai,Jung, Ho-Young Elsevier 2018 International journal of hydrogen energy Vol.43 No.39

<P><B>Abstract</B></P> <P>The unitized regenerative fuel cell (URFC) is a round-trip energy conversion device for efficient energy storage systems that offers promising electrochemical energy conversion and environmentally friendly features. The electrocatalyst is a key component for operating URFC unit cell devices. Optimal electrocatalyst materials should be bi-functional with catalytic activity for the oxygen reduction and oxygen evolution reactions (ORR and OER). Over the past few decades, platinum has been recognized as a promising bi-functional electrocatalyst material for the URFC system. However, the ORR and OER activity of Pt is inadequate during the round-trip energy conversion process due to the formation of an oxide layer (PtO<SUB>x</SUB>) and the high onset potential for H<SUB>2</SUB> evolution. To address these issues, extensive effort has been made to enhance the OER performance without affecting the ORR performance. The most efficient alternative electrocatalyst materials comprise combinations of platinum group metals (PGMs) and their oxides, especially PtIr, PtIrRu, PtIrO<SUB>2</SUB>, PtIrIrO<SUB>2</SUB>, and PtIrO<SUB>2</SUB> RuO<SUB>2</SUB>. This comprehensive review emphasizes the potential of various bifunctional electrocatalyst materials for renewable energy generation in the URFC system. Herein, we discuss the limitations of Pt electrocatalysts in the URFC-OER process based on the reaction mechanism. The classification of different bifunctional electrocatalysts is extensively reviewed and highlighted based on the structural, microstructural, fuel cell-ORR, and water electrolysis-OER characteristics, round-trip energy conversion efficiency, inadequacies, and advantages. Taking these features into account, we discuss the possibilities and performance of cost-effective bifunctional electrocatalyst materials for the ORR/OER electro-catalytic process in advanced URFC systems. This review presents an exclusive vision for the development of bifunctional electrocatalyst materials and should stimulate research on bifunctional electrode-based URFC systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> URFC is an efficient round-trip energy conversion device with high specific energy. </LI> <LI> Bifunctional electrocatalyst is a key component for operating URFC unit cell. </LI> <LI> Pt suffered by formation of PtO<SUB>x</SUB> layer and high onset potential for H<SUB>2</SUB> evolution. </LI> <LI> Pt/IrO<SUB>2</SUB> is superior electrocatalyst material for efficient ORR/OER performances. </LI> <LI> Cost-effective and novel structured electrocatalysts are an alternative to PGM. </LI> </UL> </P>

Xerogel modified diatomaceous earth microparticles for controlled drug release studies

Uthappa, U. T.,Sriram, G.,Brahmkhatri, Varsha,Kigga, Madhuprasad,Jung, Ho-Young,Altalhi, Tariq,Neelgund, Gururaj M.,Kurkuri, Mahaveer D. The Royal Society of Chemistry 2018 New Journal of Chemistry Vol.42 No.14

<P>Naturally available diatomaceous earth (DE) microparticles are ideal candidates for drug delivery due to their excellent features like biocompatibility, non-toxicity, porosity, high surface area and ease of surface modification. On the other hand, they have some limitations, especially in drug delivery applications, such as poor drug loading capacity and a very high initial burst release. In order to address these drawbacks, we have surface modified the diatoms with silica xerogel, which forms a novel hybrid material. The modification process was carried out by a facile sol-gel method, the silica xerogel decorated DE microparticles were extensively characterized by SEM, BET, ATR-IR spectroscopy and XRD in order to confirm the covalent linkage of the new material on the surface of the DE microparticles. The prepared hybrid material DE-XER (xerogel) acts as a pH-sensitive micro drug carrier for diclofenac sodium (DS) drug. The results indicate that surface modification plays a critical role, enhancing the drug loading capacity in comparison with neat DE microparticles, achieving effective controlled release. Furthermore, the obtained drug release data were fitted to the zero order model to understand the drug release mechanism.</P>

A comprehensive review on unitized regenerative fuel cells: Crucial challenges and developments

Sadhasivam, T.,Dhanabalan, K.,Roh, Sung-Hee,Kim, Tae-Ho,Park, Kyung-Won,Jung, Seunghun,Kurkuri, Mahaveer D.,Jung, Ho-Young Pergamon Press 2017 International journal of hydrogen energy Vol.42 No.7

<P><B>Abstract</B></P> <P>From extensive reported analyses, we reviewed the limitations, challenges, and advanced developments of the materials and components mainly used in the unitized regenerative fuel cell (URFC) system. URFC is a viable energy storage system owing to its high specific packaged and theoretical energy densities of 400–1000 Wh/kg and 3660 Wh/kg, respectively. Nevertheless, during the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), the stability and durability of the URFC unit cell was severely affected by various degradation factors in the stacked cell. The certain issues are related to the (i) electrocatalysts (high cost, aggregation, migration, and supportive material corrosion), (ii) dissolution and cracks in the Nafion binder, (iii) physical degradation and higher cost of polymer membrane, and severe carbon corrosion in (iv) gas diffusion packing and (v) bipolar plates. Among these factors, the critical challenges are the severe carbon corrosion and durability of the membrane in the unit cell regions. The degradation occurs in the supporting material of the electrocatalyst, gas diffusion packing, and bipolar plate owing to carbon corrosion because of the high applied potential in the water electrolyzer mode. Recent developments are significantly enhancing the durability and overcoming the limitations in the URFC system. In this comprehensive review, we have pointed out the limitations, challenges, and critical developments in URFC systems. Furthermore, built on our experimental and intellectual awareness in the context of URFC system developments, new strategies have been suggested to prepare novel structured materials and composites for advanced URFC applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> URFC is an optimum fuel cell system owing to its specific high energy density. </LI> <LI> Critical problem is severe carbon corrosion in electrocatalyst support and GDB, BP. </LI> <LI> Major challenges are cost and durability of the membrane and electrode assembly. </LI> <LI> Highly crystalline of Gr-carbon can be considered as a corrosion-resistant material. </LI> <LI> Novel structured and low cost materials are most promising to advanced URFC system. </LI> </UL> </P>

Chemodosimeter functionalized diatomaceous earth particles for visual detection and removal of trace mercury ions from water

Patil, Pravin,Madhuprasad, Pravin,Bhat, Mahesh P.,Gatti, Manasa G.,Kabiri, Shervin,Altalhi, Tariq,Jung, Ho-Young,Losic, Dusan,Kurkuri, Mahaveer Elsevier 2017 Chemical engineering journal Vol.327 No.-

<P><B>Abstract</B></P> <P>The rhodamine based receptor, P2 has been developed for the detection of environmentally hazardous Hg<SUP>2+</SUP> ions with a limit of detection, 1.5×10<SUP>−6</SUP> M. The P2 showed a significant colour change from colourless to pink upon binding with Hg<SUP>2+</SUP> ions. As a result, a new peak at 533nm was observed in UV–vis spectroscopy which was attributed to spirolactum ring opening followed by through bond energy transfer (TBET). In addition, the presence of other competing cations did not interfere the detection of Hg<SUP>2+</SUP> ions. Further, P2 has been successfully immobilized onto the naturally available and highly porous diatomaceous earth particles (P2D) for removal of Hg<SUP>2+</SUP> ions from water. The covalently attached organic molecule in P2D forms complex with Hg<SUP>2+</SUP> ion present in the water and thus traps the Hg<SUP>2+</SUP> ions. Based on this, a proof-of-concept cartridge has been developed for water purification. The cartridge having 450mg of P2D was able to purify 30mL of water containing 1ppm Hg<SUP>2+</SUP> ions. The efficiency of cartridge could be visualized with a colour change from colourless to pink.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Detection and removal of Hg<SUP>2+</SUP> from water using chemodosimeter P2 were realized. </LI> <LI> P2 has been successfully immobilized onto naturally available diatoms (P2D). </LI> <LI> Organic receptor and hazardous Hg<SUP>2+</SUP> ions were physically contained in diatoms. </LI> <LI> Eco-friendly cartridge containing P2D was developed for the removal of Hg<SUP>2+</SUP> ions. </LI> <LI> Device efficiency (time to replace) could be realized through visual colour change. </LI> </UL> </P>

High charge acceptance through interface reaction on carbon coated negative electrode for advanced lead-carbon battery system

Sadhasivam, T.,Park, Mi-Jung,Shim, Jin-Yong,Jin, Jae-Eun,Kim, Sang-Chai,Kurkuri, Mahaveer D.,Roh, Sung-Hee,Jung, Ho-Young Elsevier 2019 ELECTROCHIMICA ACTA Vol.295 No.-

<P><B>Abstract</B></P> <P>In this research, the interfacial effect between the carbon layer and the negative electrode surface is evaluated as a hybrid electrode with higher charge acceptance for the advanced lead-carbon battery (ALC-battery) system. The P-60 (activated carbon) material, with high specific surface area (1787 m<SUP>2</SUP> g<SUP>−1</SUP>) and higher electrical conductivity (98.85 S cm<SUP>−1</SUP>), is considered an efficient activated carbon in the present investigations and deposited on the negative electrode. Compared to the conventional lead-acid battery system, the carbon coated negative electrode of ALC-battery system exhibited higher capacity at the applied higher charge/discharge current. The efficient performance of the ALC-battery is mainly influenced by the thin layer of carbon on the active electrode surface, which induces higher charge acceptance. Furthermore, the ALC-battery showed an outstanding lifespan performance compared to the conventional lead-acid battery system in long-term operations. The resulting cycle life stability of lead-acid battery and ALC-battery is 2230 and 6780 cycles, respectively. The significant performance of the ALC-battery is mainly attributed by synergistic mechanism in hybrid electrode, which is resulted from interfacial effect. The likely synergetic reactions arises by carbon layer is (i) higher charge acceptance, (ii) controlled the formation of PbSO<SUB>4</SUB> crystallite in the electrode surfaces, (iii) improved electrochemical performances and Pb redox reaction due to higher electrical conductivity properties. Thus, it can be concluded that the carbon layer deposited on the negative electrode in the ALC-battery is an efficient approach for energy storage, with increased power, capacity, and enhanced cycle life stability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ALC-battery can be effectively considered for Idle Stop and Go vehicles. </LI> <LI> Synergistic effect in negative electrode enhances the ALC-battery performances. </LI> <LI> Charge acceptance of the battery is increased by carbon layer on negative electrode. </LI> <LI> Carbon layer can control the formation of larger PbSO<SUB>4</SUB> on surface of the electrode. </LI> <LI> Lifespan of ALC-battery is 3 times higher than conventional lead-acid battery. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Amine activated diatom xerogel hybrid material for efficient removal of hazardous dye

Sriram, Ganesan,Bhat, Mahesh P.,Kigga, Madhuprasad,Uthappa, U.T.,Jung, Ho-Young,Kumeria, Tushar,Kurkuri, Mahaveer D. Elsevier 2019 Materials chemistry and physics Vol.235 No.-

<P><B>Abstract</B></P> <P>The effective removal of organic pollutants from aqueous media is still an eminent challenge. In the present work, naturally available diatomaceous earth (DE) particles was surface modified with mesoporous silica xerogel denotes as diatom xerogel material. Subsequently amine functionality has been successfully introduced on diatom xerogel (DXEA) for the efficient removal of hazardous dye, Eriochrome Black T (EBT). The adsorbents before and after EBT adsorption were characterized using various techniques such as XRD, FE-SEM, FTIR and BET. The adsorption process was conducted by varying many parameters such as pH, dosage, initial concentration of dye and time. The designed adsorbent, DXEA showed increased removal efficiency (∼99 %) in comparison with neat DE (∼58 %) due to the presence of amine functional group, which favours the rapid adsorption of EBT. This study showed that adsorbent DXEA was adequate to remove 50 mg/L and 100 mg/L of aqueous EBT in 5 and 60 min of contact time respectively. The maximum dye adsorption capacity of DXEA was found to be ∼62 mg/g whereas, for DE it was ∼56 mg/g. The dye adsorption kinetics of EBT onto both the DXEA and the DE follow the pseudo-second-order model. Also, DXEA was used for selective removal of EBT in the presence of other dyes and recycle studies were discussed. These studies showed that DXEA is a promising material for EBT removal by adsorption in real sample.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Amine activated diatom xerogel adsorbent was synthesized for efficient removal of EBT. </LI> <LI> Adsorbent was analyzed using XRD, FESEM, FTIR and BET before and after dye adsorption. </LI> <LI> The designed adsorbent showed 99.9% EBT removal efficiency within 5 min. </LI> <LI> Selective removal of EBT was observed over other cationic and anionic dyes. </LI> <LI> The amine activated diatom xerogel showed good reusability even after five cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>