Step-up synthesis of amidoxime-functionalised periodic mesoporous organosilicas with an amphoteric ligand in the framework for drug delivery

Santha Moorthy, Madhappan,Park, Sung-Soo,Fuping, Dong,Hong, Sang-Hyun,Selvaraj, M.,Ha, Chang-Sik The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.18

<P>The step-up synthesis of amidoxime-functionalised periodic mesoporous organosilicas (PMOs) with an ordered hexagonal structure was achieved in two steps: (i) direct co-condensation of diaminomaleonitrile and 3-isocyanatopropyltriethoxysilane (IPTES) and (ii) chemical modification of bridged nitrile into amidoxime using a hydroxylamine hydrochloride (NH<SUB>2</SUB>OH·HCl) reagent. The synthesis approach allowed a high loading of amidoxime functional groups in the pore wall framework of the mesoporous materials with controlled regular morphologies. The resulting materials with various diureylenemaleonitrile contents (up to 40 mol%) contained ordered hexagonal mesopores. The highly ordered hexagonal arrangement of the pores with a high degree of uniformity of amidoxime-functionalised PMOs was confirmed by low-angle X-ray diffraction (XRD), N<SUB>2</SUB> adsorption isotherms, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composition of the mesoporous organosilica was further characterised by Fourier transform infrared (FT-IR) spectroscopy, <SUP>29</SUP>Si magic angle spinning (MAS) and <SUP>13</SUP>C cross-polarization (CP) MAS nuclear magnetic resonance (NMR) spectroscopy. The synthesised materials with an amphoteric ligand in the framework were found to be suitable carrier materials for controlled drug delivery systems in a phosphate buffer solution at pH 6.0, 7.4 and 9.0 for both hydrophobic (ibuprofen) and hydrophilic drugs (5-fluorouracil).</P> <P>Graphic Abstract</P><P>This paper reports new periodic mesoporous organosilicas (PMOs) with double active functional groups, <I>i.e.</I> ureylene and amidoxime groups, <I>via</I> a step-up synthesis using diaminomaleonitrile and 3-isocyanatopropyltriethoxysilane, which are suitable for controlled drug delivery systems in both hydrophobic (ibuprofen) and hydrophilic drugs (5-fluorouracil). <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm16341a'> </P>

Prussian blue decorated mesoporous silica hybrid nanocarriers for photoacoustic imaging-guided synergistic chemo-photothermal combination therapy

Santha Moorthy, Madhappan,Hoang, Giang,Subramanian, Bharathiraja,Bui, Nhat Quang,Panchanathan, Manivasagan,Mondal, Sudip,Thi Tuong, Vy Phan,Kim, Hyehyun,Oh, Junghwan The Royal Society of Chemistry 2018 Journal of materials chemistry. B, Materials for b Vol.6 No.32

<P>The fabrication of nanotherapeutic systems capable of stimuli-responsive drug delivery and photoacoustic imaging (PAI)-guided photothermal therapy (PTT) is considered significant for chemo-photothermal therapy applications in cancer therapy. In the present study, the Prussian blue nanoflake (PBNF) decorated mesoporous silica hybrid nanoparticle (PB@MSH-EDA NPs) is reported for PAI-guided chemo-photothermal therapy applications. The amine group enriched mesoporous silica channels can be used to encapsulate an anticancer drug for chemotherapy, and the surface decorated PBNFs can convert a near-infrared (NIR) laser (808 nm) into heat for photothermal therapy and can also be used for PAI applications. The PB@MSH-EDA NPs show pH-responsive drug release efficiency under acidic pH (pH 5.0 and 4.0) conditions. Furthermore, the PB@MSH-EDA NPs system shows strong NIR laser absorption and photothermal conversion efficiency under 808 nm laser irradiation. The <I>in vitro</I> experimental result shows that the PB@MSH-EDA NPs are biocompatible and could be efficiently taken up by MDA-MB-231 cells. In addition, the <I>in vivo</I> results demonstrate that the tumor-bearing mice fully recovered after injecting the drug (Dox)-loaded PB@MSH-EDA/Dox NPs and being further irradiated with the 808 nm laser. We believe that the PB@MSH-EDA NPs system could be utilized as an efficient PAI-guided chemo-photothermal therapy agent for the detection and treatment of tumors in an emerging cancer therapy application.</P>

A modified mesoporous silica optical nanosensor for selective monitoring of multiple analytes in water

Moorthy, Madhappan Santha,Cho, Hun-Jeong,Yu, Eun-Jeong,Jung, Young-Sik,Ha, Chang-Sik The Royal Society of Chemistry 2013 Chemical communications Vol.49 No.78

<P>A new modified mesoporous silica nanosensor was synthesized by the co-condensation method. Under basic conditions, the obtained mesoporous silica nanosensor responds selectively to Fe<SUP>2+</SUP> (pH = 8) and Cu<SUP>2+</SUP> (pH = 12) with a distinguishable colour change perceivable by the naked eye and a detection limit of approximately 50 ppb.</P> <P>Graphic Abstract</P><P>A modified mesoporous silica nanosensor has been synthesized for colorimetric selective detection of both Fe<SUP>2+</SUP> and Cu<SUP>2+</SUP> simultaneously using a single entity with an obvious color change under basic conditions (pH = 8 or 12, respectively). <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cc42513d'> </P>

Mesoporous organosilica hybrids with a tunable amphoteric framework for controlled drug delivery

Moorthy, Madhappan Santha,Park, Ji-Hye,Bae, Jae-Ho,Kim, Sun-Hee,Ha, Chang-Sik The Royal Society of Chemistry 2014 Journal of Materials Chemistry B Vol.2 No.38

<P>The chemical conversion of nitrile groups integrated in the pore wall frameworks of mesoporous organosilica hybrids (MSHs) into either carboxylic acid groups or amine groups by an acid or base hydrolysis method without altering the mesostructural order is suggested. By this approach, bifunctional derivatives could be produced in the silica pore walls. The nitrile groups integrated covalently into the pore walls of the mesoporous organosilica hybrids were converted to reactive functionalities, such as carboxylic acid (-COOH) or amine (-NH2) groups, by treatment with H2SO4or LiAlH4as the catalytic reagents. This facile approach allows the production of high amounts of either -COOH groups (3.26 mmol g<SUP>−1</SUP>) or amine (-NH2) groups (4.13 mmol g<SUP>−1</SUP>) into the pore walls of the mesoporous organosilica hybrids. The synthesised materials were characterised by X-ray diffraction, N2sorption isotherms, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and solid state<SUP>13</SUP>C cross-polarization magic angle spinning nuclear magnetic resonance spectroscopy (CP MAS NMR). Owing to the presence of hydrophilic basic diurea functional groups and -COOH or -NH2derivatives in the pore walls, the obtained samples could behave like bifunctional materials. The mesoporous organosilica hybrids with chemically derivatised carboxylic acid groups or amine functionalities in the pore wall frameworks were found to be suitable drug carriers for the controlled delivery of both hydrophilic (for example, 5-FU) and hydrophobic (<I>e.g.</I>IBU) drugs under an intracellular environment. The biocompatibility of the synthesised materials was also evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The cellular uptake was monitored by confocal laser scanning microscopy (CLSM). These results show that the synthesised materials have potential use as efficient carriers for drug delivery applications.</P>

Multifunctional Periodic Mesoporous Organosilicas for Biomolecule Recognition, Biomedical Applications in Cancer Therapy, and Metal Adsorption

Moorthy, Madhappan Santha,Kim, Mi‐,Ju,Bae, Jae‐,Ho,Park, Sung Soo,Saravanan, Nagappan,Kim, Sun‐,Hee,Ha, Chang‐,Sik WILEY‐VCH Verlag 2013 European journal of inorganic chemistry Vol.2013 No.17

<P><B>Abstract</B></P><P>This paper reports a new approach towards the construction of a multifunctional periodic mesoporous organosilica (PMO), which integrates a range of advantages, such as mesoporous structural order, selective nucleobase‐recognition properties, stimuli‐responsive site‐specific delivery of anticancer agents to cancer tissues, and Cu<SUP>2+</SUP> adsorption, into a single entity. First, the appropriate organic‐functional‐receptor precursor was synthesized by a chemical process and used to fabricate a multifunctional pyridine‐containing PMO material (DMPy‐PMO) by a hydrolysis and condensation route. The designed organic–inorganic hybrid mesoporous silica chemosensor showed an intrinsic selective recognition of nucleobase, specifically thymidine, through multipoint hydrogen‐bonding interactions with suitably arrayed receptor sites loaded into the rigid silica framework. An in vitro cytotoxicity test showed that the designed chemosensor materials have good biocompatibility and, therefore, could be promising candidates for the delivery of a range of therapeutic agents. Confocal laser scanning microscopy (CLSM) confirmed that the material can be internalized effectively by cancer cells (MCF‐7 cells). In addition, the DMPy‐PMOs showed efficient Cu<SUP>2+</SUP> ion removal capacity at pH 5.0 with significantly high levels of adsorption (0.95 mmol g<SUP>–1</SUP>). These results suggest that the prepared multifunctional PMO hybrid has potential use as a smart material for a range of applications, such as biomolecule recognition, biomedical applications, and as an efficient adsorbent for the removal of metal ions.</P>

Climate variability, livelihoods and social inequities: The vulnerability of migrant workers in Indian cities

Sunil D Santha,Surinder Jaswal,Devisha Sasidevan,Ajmal Khan,Kaushik Datta,Annu Kuruvilla 한국외국어대학교 국제지역연구센터 2016 International Area Studies Review Vol.19 No.1

This paper examines the vulnerability context of migrant workers in the informal sector in three Indian cities (Kochi, Surat and Mumbai), specifically in terms of how their livelihoods interface with climate variability, related hazard events and social inequities. It examines the progression of population vulnerability from a political economy perspective. The underlying assumption is that migrant workers’ vulnerability to climate variability in cities is closely embedded within the wider political economy of their day-to-day livelihood struggles. A mixed methodology design was adopted to carry out the study. Data from 50 migrants in each of the three cities were collected using a semi-structured interview schedule. The research demonstrates that urban vulnerability is a condition that shapes and reshapes itself continuously and fiercely, accompanied by the processes and structures of unplanned rapid urbanisation, environmental change and social exclusion. A significant feature of migrant workers’ vulnerability is its multi-dimensionality. This paper suggests that urban planners involved in environmental governance and risk reduction have to critically reflect on certain terminologies and practices in the field of climate change, while addressing these multi-dimensionalities.

Chitosan oligosaccharide coated mesoporous silica nanoparticles for pH-stimuli responsive drug delivery applications

Moorthy, Madhappan Santha,Hoang, Giang,Manivasagan, Panchanathan,Mondal, Sudip,Vy Phan, Thi Tuong,Kim, Hyehyun,Oh, Junghwan Springer-Verlag 2019 Journal of porous materials Vol.26 No.1

Dynamic smile reanimation in facial nerve palsy

Krishnakumar Krishnan Santha,Subin Joseph,Sameer Latheef,Saju Narayanan,Santhy Mohanachandran Nair,Bibilash Babu,Anand Sivadasan,Srivatsa Manjunath Shet,Rajesh Vardhan Pydi,Ajit Pati,Srikant Aruna Sam 대한구강악안면외과학회 2020 대한구강악안면외과학회지 Vol.46 No.2

Objectives: Long-term facial paralysis results in degeneration of the distal nerve segment and atrophy of the supplied muscles. Options for these patients include free muscle transfer, temporalis myoplasty, and botulinum toxin injections for smile reanimation. In this study we aimed to evaluate the subjective and objective outcomes of these procedures. Materials and Methods: In our study, we retrospectively analyzed smile symmetry in patients with facial palsy (n=8) who underwent facial reanimation procedures. Results: Subjective analysis showed high satisfaction in seven out of eight patients. Objective analysis showed statistically significant improvement postoperatively in both vertical and horizontal smile symmetry at rest and during maximum smile (P<0.001). Conclusion: Choosing the ideal procedure for the patients is the most critical aspect for facial reanimation. Though free muscle transfer is considered gold standard procedure, temporalis myoplasty also gives satisfactory results. Residual synkinesis which can lead to disturbing aesthetic deformity can be effectively treated with botulinum toxin.

Analysis of dual‑input three‑port isolated DC–DC converter with bidirectional capability

Arulmozhi Subramanian,Santha Karuppiah 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.4

Multiport converters gain prominent importance in electric vehicle (EV) and DC micro-grid applications for their capability to integrate multiple renewable power sources and energy storage systems. The stored energy in the battery balances the load demand during intermittent power generation from the photovoltaic (PV) source. However, charging the drained battery in the complete absence of PV power interrupts the overall operation of the system. Hence, a modified dual-input three-port isolated bidirectional converter is proposed to handle bidirectional power transfer in the output port and to utilize available power for battery charging. Implementation of a mode selection logic controller with optimal maximum power point tracking and pulse width modulated controllers improves the reliability of the converter. The equivalent circuit of the proposed topology and its mathematical model help evaluate the loss of components at different conduction intervals. The computed device losses, inductor and capacitor equivalent series resistance losses, and other losses clearly depict the effect on the performance of the proposed converter. Thus, the predicted efficiency is validated by the experimental data of the laboratory prototype, substantiating the performance of the converter.

Modified high-efficiency bidirectional DC-DC converter topology

Somalinga, Sethuraman S.,Santha, Karuppiah The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

A modified topology to obtain a high efficiency bidirectional type DC-DC converter without magnetic coupling is proposed in this paper. The modified circuit contains four switches with their body diodes, two inductors and a capacitor, and the topology arrangement uses two boost converters to develop the gain. The input current of the modified topology is divided between two different values of inductors, which results in high efficiency. In the buck mode, an obvious reduction in the voltage gain and an improved efficiency can be seen using synchronous rectification. The modified topology improves performance, allows for easy control structures and can be used in low output voltage high current battery charging applications. Simulations of the proposed system have been carried out through MATLAB/SIMULINK software. In addition, it has been validated through a 12 V/120 V, 40 W prototype circuit.