Chitin and chitosan: Properties and applications

Spurred by recent progress in materials chemistry and drug delivery, stimuli-responsive devices that deliver a drug in spatial-, temporal- and dosage-controlled fashions have become possible. Implementation of such devices requires the use of biocompatible materials that are susceptible to a specific physical incitement or that, in response to a specific stimulus, undergo a protonation, a hydrolytic cleavage or a (supra)molecular conformational change. In this Review, we discuss recent advances in the design of nanoscale stimuli-responsive systems that are able to control drug biodistribution in response to specific stimuli, either exogenous (variations in temperature, magnetic field, ultrasound intensity, light or electric pulses) or endogenous (changes in pH, enzyme concentration or redox gradients).

Stimuli-responsive nanocarriers for drug delivery

Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

12.2.2. Four-Wave Mixing (FWM) 4849 12.2.3. Dye Aggregation 4850 12.2.4. Optoelectronic Nanodevices 4850 12.3. Sensor 4851 12.3.1. Chemical Sensor 4851 12.3.2. Biological Sensor 4851 12.4. Catalysis 4852 13. Conclusion and Perspectives 4852 14. Abbreviations 4853 15. Acknowledgements 4854 16. References 4854 * Corresponding author E-mail: tpal@chem.iitkgp.ernet.in. † Raidighi College. § Indian Institute of Technology. 4797 Chem. Rev. 2007, 107, 4797−4862

Interparticle Coupling Effect on the Surface Plasmon Resonance of Gold Nanoparticles: From Theory to Applications

Functional Nanomaterials for Phototherapies of Cancer

The coil-to-globule transition of a single chain of narrowly distributed (Mz/Mw lo7 glmol) poly(N-isopropylacrylamide) in extremely dilute solutions (-5 pgl mL) was studied by both static and dynamic laser light scattering. The thermodynamically stable collapsed globule (R&?h = 0.97) was observed for the first time. However, when R.&, < 0.97, the single-chain globules were "metastable"; Le., the globules in the solution were stable only for a finite time. Two-stage chain collapsing kinetics in the thermodynamically stable region was observed. The time scales (-lo2 s) observed in both the chain collapsing and dissolving processes are too short to support the previously suggested high chain-knotting density inside the globule. The R&, can be as low as -0.62, lower than 0.774 predicted for a uniform density sphere. This paradox suggests that the chain density is higher at the center of the globule than that near the surface. The highly collapsed globule still contains -80% water in its hydrodynamic volume.

Laser Light Scattering Study of the Phase Transition of Poly(N-isopropylacrylamide) in Water. 1. Single Chain

The low solubility of fullerenes in aqueous solution limits their applications in biology. By appropriate substitution, the fullerenes can be transformed into stabilized anions that are water soluble and can form large aggregated structures. A laser light scattering study of the association behavior of the potassium salt of pentaphenyl fullerene (Ph5C60K) in water revealed that the hydrocarbon anions Ph5C60- associate into bilayers, forming stable spherical vesicles with an average hydrodynamic radius and a radius of gyration of about 17 nanometers at a very low critical aggregation concentration of less than 10(-7) moles per liter. The average aggregation number of associated particles in these large spherical vesicles is about 1.2 x 10(4).

https://science.sciencemag.org/content/sci/291/5510/1944.full.pdf

Spherical bilayer vesicles of fullerene-based surfactants in water: a laser light scattering study

Optical detection of glucose, high drug loading capacity, and self-regulated drug delivery are simultaneously possible using a multifunctional hybrid nanogel particle under a rational design in a colloid chemistry method. Such hybrid nanogels are made of Ag nanoparticle (NP) cores covered by a copolymer gel shell of poly(4-vinylphenylboronic acid-co-2-(dimethylamino)ethyl acrylate) [p(VPBA−DMAEA)]. The introduction of the glucose sensitive p(VPBA−DMAEA) gel shell onto Ag NPs makes the polymer-bound Ag NPs responsive to glucose. While the small sized Ag cores (10 ± 3 nm) provide fluorescence as an optical code, the responsive polymer gel shell can adapt to a surrounding medium of different glucose concentrations over a clinically relevant range (0−30 mM), convert the disruptions in homeostasis of glucose level into optical signals, and regulate release of preloaded insulin. This shows a new proof-of-concept for diabetes treatment that exploits the properties from each building block of a multifunctional na...

Multifunctional hybrid nanogel for integration of optical glucose sensing and self-regulated insulin release at physiological pH.

A series of lightly cross-linked, nearly monodisperse, and random copolymerized microgel particles, based on methacrylic acid (MAA) and N-isopropylacrylamide (NIPAM) of various content, were synthesized in aqueous solution with sodium dodecyl sulfate at pH = 3.1 ± 0.2 and 70 °C. The polymerization kinetics, the colloidal stability, and the size of the microgel particles varied with the comonomer composition. The volume phase transitions of the MAA/NIPAM copolymer microgel particles with different PMAA contents in very dilute aqueous solution (C< 1 × 10-5 g/mL) were investigated by laser light scattering (LLS), as a function of both pH at 25 °C, and temperature at two different pH values of 3.4 and 7.5. To our knowledge, the volume phase transition of such submicron-sized hydrogels sensitive to multiple environmental changes was studied for the first time by LLS. The equilibrium swelling ratio, the critical transition pH, and the critical transition temperature (Tc) were strongly dependent on the comonomer...

Shuiqin Zhou

Papers

Laser Light Scattering Study of the Phase Transition of Poly(N-isopropylacrylamide) in Water. 1. Single Chain

Spherical bilayer vesicles of fullerene-based surfactants in water: a laser light scattering study

Multifunctional hybrid nanogel for integration of optical glucose sensing and self-regulated insulin release at physiological pH.

Synthesis and Volume Phase Transition of Poly(methacrylic acid-co-N-isopropylacrylamide) Microgel Particles in Water

Synthesis and volume phase transitions of glucose-sensitive microgels.