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Palanikumar, L.,Choi, Eun Seong,Oh, Jun Yong,Park, Soo Ah,Choi, Huyeon,Kim, Kibeom,Kim, Chaekyu,Ryu, Ja-Hyoung American Chemical Society 2018 Biomacromolecules Vol.19 No.7
<P>Current drug delivery systems are hampered by poor delivery to tumors, in part reflecting poor encapsulation stability of nanocarriers. Although nanocarriers such as polymeric micelles have high colloidal stability and do not aggregate or precipitate in bulk solution, nanocarriers with low encapsulation stability can lose their cargo during circulation in blood due to interactions with blood cells, cellular membranes, serum proteins, and other biomacromolecules. The resulting premature drug release from carriers limits the therapeutic efficacy at target sites. Herein, we report a simple and robust technique to improve encapsulation stability of drug delivery systems. Specifically, we show that installation of disulfide cross-linked noncovalent polymer gatekeepers onto mesoporous silica nanoparticles with a high loading capacity for hydrophobic drugs enhances <I>in vivo</I> therapeutic efficacy by preventing premature release of cargo. Subsequent release of drug cargos was triggered by cleavage of disulfide cross-linking by glutathione, leading to improved antitumor activity of doxoroubicin in mice. These findings provide novel insights into the development of nanocarriers with high encapsulation stability and improved <I>in vivo</I> therapeutic efficacy.</P> [FIG OMISSION]</BR>
Palanikumar, L.,Kim, Ho Young,Oh, Joon Yong,Thomas, Ajesh P.,Choi, Eun Seong,Jeena, M. T.,Joo, Sang Hoon,Ryu, Ja-Hyoung American Chemical Society 2015 Biomacromolecules Vol.16 No.9
<P>Advances in water-insoluble drug delivery systems are limited by selective delivery, loading capacity, and colloidal and encapsulation stability. We have developed a simple and robust hydrophobic-drug delivery platform with different types of hydrophobic chemotherapeutic agents using a noncovalent gatekeeper’s technique with mesoporous silica nanoparticles (MSNs). The unmodified pores offer a large volume of drug loading capacity, and the loaded drug is stably encapsulated until it enters the cancer cells owing to the noncovalently bound polymer gatekeeper. In the presence of polymer gatekeepers, the drug-loaded mesoporous silica nanoparticles showed enhanced colloidal stability. The simplicity of drug encapsulation allows any combination of small chemotherapeutics to be coencapsulated and thus produce synergetic therapeutic effects. The disulfide moiety facilitates decoration of the nanoparticles with cysteine containing ligands through thiol–disulfide chemistry under mild conditions. To show the versatility of drug targeting to cancer cells, we decorated the surface of the shell-cross-linked nanoparticles with two types of peptide ligands, SP94 and RGD. The nanocarriers reported here can release encapsulated drugs inside the reducing microenvironment of cancer cells via degradation of the polymer shell, leading to cell death.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bomaf6/2015/bomaf6.2015.16.issue-9/acs.biomac.5b00589/production/images/medium/bm-2015-00589d_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/bm5b00589'>ACS Electronic Supporting Info</A></P>
Measurement of Diesel Exhaust Fluid Concentration in Urea-SCR after-Treatment System
PalaniKumar Gurusamy,Uma Gandhi,Umapathy Mangalanathan,Karl Marx LR 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.8
In an effort to meet the established emission standards Selective Catalytic Reduction (SCR) is used to reduce NOx emissions with diesel exhaust fluid (DEF) as additive in the exhaust of diesel engines. ISO 22241-1:2006 specifies the quality characteristics of DEF in order to maintain efficiency and hence, it is essential that the concentration of urea in DEF is accurately monitored. In this paper, a measurement system is designed, developed and tested for measuring the concentration of urea in DEF. The design involves piezoelectric ultrasound transmitter and receiver with associated electronics operating at a frequency of 4 MHz. The concentration of urea in DEF is measured (i) by measuring the time of flight of ultrasound waves between transmitter and receiver (ii) by measuring the amplitude of received signal in terms of frequency using voltage-to-frequency converter. The measurement system is modeled using two-port network model for piezoelectric transmitter/receiver and transmission line model for DEF medium. The prototype of measurement system is fabricated with all associated electronics and tested for variation in concentration of urea in DEF. The results from prototype are in close agreement with the results obtained from analytical model. The measurement system is tested for repeatability and sensitivity to temperature.
K. Palanikumar,B. Latha,V. S. Senthilkumar,R. Karthikeyan 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.2
Optimization of cutting parameters is important to achieving high quality in the machining process, especially where more complex multiple performance optimization is required. The present investigation focuses on the multiple performance optimization on machining characteristics of glass fiber reinforced plastic (GFRP) composites. The cutting parameters used for the experiments, which were carried out according to Taguchi’s L27, 3-level orthogonal array, were cutting speed, feed and depth of cut. Statistical models based on secondorder polynomial equations were developed for the different responses. The Non-dominated Sorting Genetic Algorithm (NSGA-II) tool was used to optimize the cutting conditions, yielding a non-dominated solution set that is reported here. Optimization of cutting parameters is important to achieving high quality in the machining process, especially where more complex multiple performance optimization is required. The present investigation focuses on the multiple performance optimization on machining characteristics of glass fiber reinforced plastic (GFRP) composites. The cutting parameters used for the experiments, which were carried out according to Taguchi’s L27, 3-level orthogonal array, were cutting speed, feed and depth of cut. Statistical models based on secondorder polynomial equations were developed for the different responses. The Non-dominated Sorting Genetic Algorithm (NSGA-II) tool was used to optimize the cutting conditions, yielding a non-dominated solution set that is reported here.
Rajasekaran T.,Palanikumar K.,Latha B. 한국탄소학회 2022 Carbon Letters Vol.32 No.2
Carbon fiber and its composites are increasingly used in many fields including defence, military, and allied industries. Also, surface quality is given due importance, as mating parts are used in machineries for their functioning. In this work, the turning process is considered for Carbon Fiber Reinforced Polymer (CFRP) composites by varying three important cutting variables: cutting speed, feed, and depth of cut. Correspondingly, the surface roughness is measured after the completion of turning operation. As well, a prediction model is created using different fuzzy logic membership function and Levenberg–Marquardt algorithm (LMA) in artificial intelligence. Later, the surface roughness values from the developed models are compared against the experimental values for its correlation and effectiveness in using different membership functions of fuzzy logic and ANN. Thus, the experimental results are analyzed using the effect graphs and it is presented in detail.
Intra-mitochondrial biomineralization for inducing apoptosis of cancer cells
Kim, Sangpil,Palanikumar, L.,Choi, Huyeon,Jeena, M. T.,Kim, Chaekyu,Ryu, Ja-Hyoung Royal Society of Chemistry 2018 Chemical Science Vol.9 No.9
<▼1><P>Mitochondria targeting mineralization can form biominerals inside cancerous mitochondria through concentration dependent silicification, resulting in dysfunction of mitochondria leading to apoptosis. These results suggest potential therapeutics for cancer treatment.</P></▼1><▼2><P>The use of biomineralization that regulates cellular functions has emerged as a potential therapeutic tool. However, the lack of selectivity still limits its therapeutic efficacy. Here, we report a subcellular-targeting biomineralization system featuring a triphenylphosphonium cation (TPP) (the mitochondria-targeting moiety) and trialkoxysilane (the biomineralization moiety <I>via</I> silicification). The TPP-containing trialkoxysilane exhibited approximately seven times greater cellular uptake into cancer cells (SCC7) than into normal cells (HEK293T) due to the more negative mitochondrial membrane potentials of the cancer cells. In turn, its accumulation inside mitochondria (pH 8) induces specific silicification, leading to the formation of silica particles in the mitochondrial matrix and further activation of apoptosis. <I>In vivo</I> assessment confirmed that the biomineralization system efficiently inhibits tumor growth in a mouse xenograft cancer model. Exploiting both the subcellular specificity and the targeting strategy provides new insight into the use of intracellular biomineralization for targeted cancer therapy.</P></▼2>