PH -controlled release

RA Siegel, M Falamarzian, BA Firestone, BC Moxley. pH controlled release from hydrophobic poly electrolyte copolymer hydrogels. J Controlled Release 8 179-182, 1988. 

Self-assembly of polymers in the bulk Polymer micelles, polymero-somes, gelled macromole-cules, nano-tubes, protein fibres/tapes produced by aggregation at low pH, controlled release vehicles, smart delivery systems 50-500 nm Forster and Konrad, 2003 Sanguansri and Augustin, 2006 Dickinson 2006a Graveland-Bikker and de Kruif, 2006 van der Linden, 2006... 

Ju, T., Cooper, A., Gauri, V., and Patel, M. pH controlled release oral drug delivery Effects of bulk and iternal pH. Paper no. PDD 7491, AAPS Annual Meeting, San Diego, CA, 1994. 

Ulbrich K, Etrych T, Chytil P, Jelinkova M, Rihova B. HPMA copolymers with pH-controlled release of doxorubicin. In vitro cytotoxicity and in vivo antitumour activity. J Cont Rel 2003 87 33- 7. 

Siegel RA, Falamarzian M, Firestone BA, Moxley BC. pH-controlled release from hydrophobic/polyelectrolyte copolymer hydrogels. J Contr Rel 1988 8 179-182. 

With regard to the preparation of multicompartment polymer capsules based on this SIP method, a successful approach was demonstrated by Kang et al. [17] who used a two-step distillation/precipitation polymerization of methacrylic acid (MAA) and A-isopropylacrylamide (NIPAM), respectively, onto silica nanoparticles as templates. More interestingly, due to the PMAA inner shell and PNIPAM outer shell, the hollow structure can respond independently to changes in pH and temperature. After loading DOX into the capsules, temperature- and pH-controlled release of anticancer drug behavior was demonstrated. 

T. Mrkvan, M. Slrovd, T. Etrych, P. Chytil, J. Strohalm, D. Plocovd, K. Ulbrich and B. Rihovd, Chemotherapy based on HPMA copolymer conjugates with pH-controlled release of doxorubicin triggers anti-tumor immunity, J. Control. Release, 110, 119-129 (2005). 

Michalak, M., Marek, A.A., Zawadiak, J., Kawalec, M., Kurcok, P., 2013. Synthesis of PHB-based carrier for drug delivery systems with pH-controlled release. Eur. Polym. J. 49, 4149-4156. 

Ref 11). The pH of a satd soln in w was measured with a glass electrode and found to be 0.6 (Ref 25, p 2) CA Registry No 517-25-9. The Hercules Powder Co of Wil-mington, Del has been granted a trademark for Nitroform , a synthetic w-insoluble compd for controlled release of N for agricultural use (Ref 40). This should not be confused with TNMe... 

The simulation data of pH 7.0 and uncontrolled pH was compared to the experimental data. (Fig. 1 and 2) The settling was assumed to ideal settling. The pH of pH-uncontrolled SBR was about 8.5. The phosphate profile showed relatively the same result with a general EBPR process. Under pH-uncontrolled condition, phosphate was released to the bulk solution in the anaerobic phase and removed in the subsequent aerobic phase both in simulation and in the experiment. This is the typical result of a good EBPR process. Under pH-controlled condition, phosphate was neither released nor removed both in the simulation and in the experiment. 

A predictable delivery rate independent of environmental factors such as viscosity, pH, water content, and stirring rate (i.e., GI motility) Controllable release rates during the delivery period Delivery characteristics independent of the properties of the drug (e.g., aqueous solubility)... 

L-C Dong, AS Hoffman. A novel approach for preparation of pH-sensitive hydrogels for enteric drug delivery. J Controlled Release 15 141-152, 1991. 

Concerning drug delivery, electrically erodible polymer gels for controlled release of drugs have been prepared, and a measured release rate of insulin has been observed under electrical stimulus [69]. A suspension of zinc insulin in a mixed solution of poly(ethyloxazoline) and PMAA was formed into a gel by decreasing the pH of the suspension. The obtained complex gel with 0.5 wt% of insulin was attached to a woven platinum wire cathode which was 1 cm away from the anode and immersed in 0.9% saline solution. When a stepped function of electrical current of 5 mA was applied to the insulin-loaded gel matrix, insulin was released in a stepwise manner up to a release of 70%. The insulin rate measured was 0.10 mg/h. 

Ubrich, N., Bouillot, Ph., Pellerin, Ch., Hoffman, M. and Maincent Ph. (2004) Preparation of propranolol hydrochloride nanopartides a comparative study. Journal of Controlled Release, 97 291-300. 

Bulmus V, Woodward M, Lin L, Murthy N, Stayton P, Hoffman A (2003) A new pH-responsive and glutathione-reactive, endosomal membrane-disruptive polymeric carrier for intracellular delivery of biomolecular drugs. J Control Release 93 105-120... 

Wang XL, Xu R, Lu ZR (2009) A peptide-targeted delivery system with pH-sensitive amphiphilic cell membrane disruption for efficient receptor-mediated siRNA delivery. J Control Release 134 207-213... 

Boeckle S, Fahrmeir J, Roedl W, Ogris M, Wagner E (2006) Melittin analogs with high lytic activity at endosomal pH enhance transfection with purified targeted PEI polyplexes. J Control Release 112 240-248... 

Murthy N, Campbell J, Fausto N, Hoffman AS, Stayton PS (2003) Design and synthesis of pH-responsive polymeric carriers that target uptake and enhance the intracellular delivery of oligonucleotides. J Control Release 89 365-374... 

Yuba E, Kojima C, Sakaguchi N, Harada A, Koiwai K, Kono K (2008) Gene delivery to dendritic cells mediated by complexes of lipoplexes and pH-sensitive fusogenic polymer-modified liposomes. J Control Release 130 77-83... 

Lee ES, Shin HJ, Na K et al (2003) Poly(L-histidine)-PEG block copolymer micelles and pH-induced destabilization. J Control Release 90 363-374... 

Lin YH, Sonaje K, Lin KM et al (2008) Multi-ion-crosslinked nanoparticles with pH-responsive characteristics for oral delivery of protein drugs. J Control Release 132 141-149... 

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