H Rumpel

Publications (2)7.36 Total impact

• Source

  Available from: ntu.edu.sg

  Article: Thermoresponsive core-shell magnetic nanoparticles for combined modalities of cancer therapy.

  S Purushotham, P E J Chang, H Rumpel, I H C Kee, R T H Ng, P K H Chow, C K Tan, R V Ramanujan
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  ABSTRACT: Thermoresponsive polymer-coated magnetic nanoparticles loaded with anti-cancer drugs are of considerable interest for novel multi-modal cancer therapies. Such nanoparticles can be used for magnetic drug targeting followed by simultaneous hyperthermia and drug release. Gamma-Fe(2)O(3) iron oxide magnetic nanoparticles (MNP) with average sizes of 14, 19 and 43 nm were synthesized by high temperature decomposition. Composite magnetic nanoparticles (CNP) of 43 nm MNP coated with the thermoresponsive polymer poly-n-isopropylacrylamide (PNIPAM) were prepared by dispersion polymerization of n-isopropylacrylamide monomer in the presence of the MNP. In vitro drug release of doxorubicin-(dox) loaded dehydrated CNP at temperatures below and above the lower critical solution temperature of PNIPAM (34 degrees C) revealed a weak dependence of drug release on swelling behavior. The particles displayed Fickian diffusion release kinetics; the maximum dox release at 42 degrees C after 101 h was 41%. In vitro simultaneous hyperthermia and drug release of therapeutically relevant quantities of dox was achieved, 14.7% of loaded dox was released in 47 min at hyperthermia temperatures. In vivo magnetic targeting of dox-loaded CNP to hepatocellular carcinoma (HCC) in a buffalo rat model was studied by magnetic resonance imaging (MRI) and histology. In summary, the good in vitro and in vivo performance of the doxorubicin-loaded thermoresponsive polymer-coated magnetic nanoparticles suggests considerable promise for applications in multi-modal treatment of cancer.
  Nanotechnology 08/2009; 20(30):305101. · 3.98 Impact Factor
• Article: Spermine reduces infarction and neurological deficit following a rat model of middle cerebral artery occlusion: a magnetic resonance imaging study.

  M D Shirhan, S M Moochhala, P-Y Ng, J Lu, K C Ng, A L Teo, E Yap, I Ng, P Hwang, T Lim, Y Y Sitoh, H Rumpel, R Jose, E Ling
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  ABSTRACT: The role of nitric oxide (NO) in post-ischemic cerebral infarction has been extensively examined, but few studies have investigated its role on the neurological deficit. In the present study, we investigated the effect of spermine on the temporal evolution of infarct volume, NO production and neurological deficit using magnetic resonance imaging in a model of permanent focal cerebral ischemia in rats. Spermine given at 10 mg/kg 2 h after ischemia reduced the infarct volume by 40% and abolished brain NO production and improved the neurological score 24 h, 48 h and 72 h after ischemia. Spermine also reduced the neurological deficit as evaluated by rotamex, grip strength and neurological severity score tests.
  Neuroscience 02/2004; 124(2):299-304. · 3.38 Impact Factor