Iii Stability And Toxicity Of Polyalkylcyanoacrylate Nanoparticles
Degradation and toxicity of poly alkylcyanoacrylates is often discussed in the literature especially for the in vivo applications of nanoparticles as drug delivery systems. Concerning the stability of the nanoparticles, different pathways for their degradation have been described. The predominent mechanism greatly depends on the experimental conditions. Among the known degradation pathways, the most likely to occur in vivo are of two kinds. One mechanism consists of hydrolysis of the ester bond...
E Influence of the Surface Charge Density
The effect of the latex surface density on dT35 grafting was studied using various latexes. As expected, the greater the cationic charge on the latex surface, the higher the dT35 adsorption through electrostatic interactions, as illustrated in Figure 23. The extrapolation to zero charge provides 0.35 mg m2 immobilized FIG. 23 Influence of the overall charge density of the latexes on the adsorbed and grafted dT35 amounts. O immobilized dT35 covalently grafted dT35. From Ref. 26. dT35, slightly...
C Mechanism and Kinetics of Protein Adsorption onto Particles
There were some inconsistencies in the results on protein adsorption reported by different researchers. This is attributed to the different conditions for adsorption, i.e., different surface properties, different concentration of particles, different dispersion media, etc. However, some general facts have been observed as presented below. The factors controlling protein adsorption were comprehensively studied by Haynes, Norde, et al. 1 . They concluded that protein adsorption is controlled by...
B Synthesis and Characterization of Functionalized Polystyrene Beads
Polystyrene microspheres SX3 35-75 pm in diameter, Biorad were modified in three steps Fig. 6 . First, 10 mol of monochlorosulfonic acid HSO3CI excess was added to polystyrene in dichloromethane CH2Cl2 . The mixture was stirred at room temperature for 1 h, then the suspension was filtered and washed with CH2C12. This nucleophile substitution led to poly parachlorosulfonyl styr-ene a reactive intermediate immediately used in the second step of the func-tionalization process. Poly...
A Bound Antibody Latex
In order to increase the efficiency of antigen binding onto modified polymer and the sensitivity of virus detection, oriented binding of antibodies onto polymer surface appeared to be of great interest. To reach this aim, virus-specific antibodies were covalently bound onto latex particles by using carbodiimide reagent techniques 16,17 . Flow cytometry was used to detect and to quantify virus-bound latex particles by fluorescence. This technique requires the micro-spheres to be coated with a...
REFERENCES Jwj
1. Kawaguchi, H. Asai, A. Ohtsuka, Y. Watanabe, H. Wada, T. Handa, H. Nucleic Acids Res. 1989, 17 5 , 6229. 2. Ganachaud, F. Mouterde, G. Delair, T. Elaissari, A. Pichot, C. Polym. Adv. Tech. 1995, 6, 480. 3. Ganachaud, F. Sauzedde, F. Elaissari, A. Pichot, C. J. Appl. Polym. Sci. 1997, 65, 2315. 4. Sauzedde, F. Ganachaud, F. Elai'ssari, A. Pichot, C. J. Appl. Polym. Sci. 1997, 65, 2331. 5. Ganachaud, F. Bouali, B. Veron, L. Lanteri, P. Elaissari, A. Pichot, C. Colloid Surf. A Physicochem. Eng....
A Taste Masking
Taste masking of active drugs appears to be a key issue of the development of new oral or liquid dosage forms, such as orodispersible tablets or pediatric suspensions. A large number of drugs exhibit a bad taste, which can result in the low observance of the treatment by the patient. This is especially true for antibiotics, which are very bitter compounds, but anti-infectious drugs or drugs for the treatment of the central nervous system disorders may also require a taste-masking formulation...
A Adsorption Isotherms
When protein adsorption occurs it takes a certain time before the adsorbed amount and the protein concentration in solution reach their equilibrium values. When the equilibrium adsorption values are determined as a function of the equilibrium protein concentration in solution, an adsorption isotherm is obtained. Measurement of an adsorption isotherm is the starting point of most protein adsorption studies. By measuring adsorption isotherms under several experimental conditions one tries to...
REFERENCES Pba
1. Haynes, C.A. Norde, W. Colloids Surf. B Biointerfaces 1994, 2, 517. 2. Bagchi, P. Birnbaum, S.M. J. Colloid Interface Sci. 1981, 83, 460. 3. Basinska, T. J. Biomater. Sci. Polym. Ed. 2001,12, 1359. 4. Lacasse, F.X. Filion, M.C. Phillips, N.C. Escher, E. McMullen, J.N. Hilgen, P. Pharm. Res. 1998, 15, 312. 5. Tanaka, M. Colloids Surf. A 2001, 193, 145. 6. Vroman, L. Adams, A. L. Fischer, G. C. Muhoz, P. C. Blood, 1980, 55, 156. 7. Yoon, J.-Y. Kim, J.-H. Kim, W.-S. Colloids Surf. A Phys. Eng....
Iinonspecific Protein Adsorption Behavior Of Latex Particles
The nonspecific protein adsorption behaviors of monodispersed latex particles prepared with different surface chemistries were extensively investigated 1-4 . In the most of these studies, the polystyrene-based latex particles in submicro- meter size range were prepared by the conventional emulsion polymerization of styrene or the emulsion copolymerization of styrene with the functional acrylic monomers e.g., 2-hydroxyethyl methacrylate HEMA , acrylic acid, and acryl-amide 1-3 . These latexes...
B Functionalized Particles
Many kinds of functionalized latexes with reactive surface groups suitable for covalent protein immobilization have been described. Some of the more common choices include the following The most commonly used surfaces for attachment of ligands are carboxyl and amino groups, for the following reasons 1. These groups have proven to be very stable over time. 2. The chemistries involved in attaching ligands to either of these groups have been widely explored, and several options exist for each. 3....
A Colloidal Stability
One of the basic requirements for a protein-latex complex to be applicable to clinical diagnostics is colloidal stability under immunological conditions. However, as indicated in the introduction, the most serious problem in latex immunoagglutination assays is that the system can lose its colloidal stability after antibody adsorption step. This low colloidal stability of latex-antibody complexes in the reaction medium may provoke the nonspecific agglutination of particles. The isoelectric point...
peptide
FIG. 11 Use of nonpeptidic spacers for peptide immobilization. Nonpeptidic spacers have advantages over peptidic ones, especially in terms of undesired reactivity with the antibody. Furthermore, the bound spacer may bear a functional group at the free end and thus allow changing of the reactive properties of a given surface. ethylene glycol 58,59 , can improve peptide exposure to aqueous phase, where otherwise the peptide would tend to interact with the surface Fig. 12 . In addition, any spacer...
References
1. Furusawa, K. Nagashima, K. Anzai, C. Synthetic process to control the total size and component distribution of multilayer magnetic composite particles. Colloid Polym. Sci. 1994, 272 9 , 1104-1110. 2. Chen, T. Somasundaran, P. Preparation of core-shell nanocomposite particles by controlled polymer bridging. J. Am. Ceram. Soc. 1998, 81 1 , 140-144. 3. Bamnolker, H. Nitzar, B. Gura, S. Margel, S. New solid and hollow, magnetic and non-magnetic, organic-inorganic monodispersed hybrid...
E Effect of pH
The investigation of the effect of pH on the adsorption of charged macromole-cules onto charged solid support is of paramount importance. In fact, the pH FIG. 9 a Adsorption isotherms of oligonucleotide onto bare latex particles. Samples were mixed and incubated for 2 h at 20 C, 10-2 M ionic strength at a given pH. b Adsorption isotherms of oligonucleotide onto precoated latex particles by adsorbing small amount of Triton-X405 . Samples were mixed and incubated for 2 h at 20 C, 10-M ionic...
V POLYELECTROLYTEPARTICLE COMPLEXES A Influence of the Polymer Length
To investigate adsorption processes in the polyelectrolyte-particle system, a spherical charged particle Q 100, op 35.7 A is added to the equilibrated polyelectrolyte chain N 100, lt 5m 3.57 A, f 1, lB 7.14 A so that they are close with each other. Then the polyelectrolyte-particle complex is enclosed in a spherical cell and allowed to relax. Equilibrated conformations of the complex as a function of C and N are presented in Table 3. It should be noted that the TABLE 3 Equilibrated...
Ii Basic Concepts
Lactides and e-caprolactone can be polymerized according to cationic, anionic, and pseudoanionic mechanisms. The mechanisms and kinetics of these processes have been investigated in detail 9-30 . All of these processes have to be carried out in organic media at anhydrous conditions because in ionic and pseudoionic polymerizations compounds with labile protons e.g., water and alcohols act as termination and or chain transfer agents. Thus, all procedures developed for more than a century for...
C Immunomagnetic Separation of Bacteria
Immunomagnetic separation is based on the specific antigen-antibody reaction common to all of the immunoassays presented above. The immobilization of antibodies on a solid phase spurred the development of sandwich tests or ELISA 38 . Selective separation is a function of the specific epitope of the biomolecule under consideration the efficacy in term of reactivity of the immobilized antibodies on the surface of the magnetic particles depends primarily on their orientation on the surface of the...
B Light Scattering Techniques
Latex looks like milky white because the submicrometer particles scatter visible light. Developments in instrumentation have permitted the automatically full quantification of the immunological agglutination by light scattering, thus avoiding the subjectiveness of manual detection. These instrumental methods are far more sensitive than visual detection of the aggregates. Light scattering can be measured with rather inexpensive and simple instruments that are commercially available. The...
Monodispersemacroporous Particles
As mentioned before, the monodisperse-macroporous particles are suitable as chromatographic packing materials, particularly in the HPLC applications. Ugel- FIG. 12 Binding of several PCMS particles onto one DNA molecule via the interaction between primary amine groups of PEI and phosphate groups of DNA. Reprinted with permission from Ref. 24, Copyright 2001, VSP International Science Publishers. stad et al. were the first to propose the use of monodisperse-macroporous...
CEffect of Ionic Strength on the Protein Desorption
The effect of ionic strength on the desorption of preadsorbed proteins above the transition temperature i.e., 40 C was also discussed and found to be of great interest as reported by Duracher 32 . In fact, the desorption investigated in the case of an oppositely charged system at a given pH as a function of salt concentration was found to dramatically increase from 50 to 95 of the desorbed amount. This was attributed to the screening effect of electrolytes which reduces FIG. 10 Protein desorbed...
A Influence of Adsorption Incubation Time on the Desorption of Proteins
The first experiments on the desorption of proteins revealed the complexity of the adsorption-desorption process. In fact, adsorption is principally amplified when performed above the rWT 11 . Desorption was found to be effective by lowering of the incubation temperature. In addition, the desorbed protein was directly related to the incubation time during the adsorption process above the rVPT as reported below in the case of cationic thermally sensitive latexes Fig. 9 . As evidenced in Fig. 6,...
B Effect of Nonionic Surfactant on the Desorption of Oligonucleotide
Since the adsorption of oligonucleotides onto coated cationic latex particles is reduced irrespective of pH and ionic strength, ODN desorption was first investigated by washing the latex particles bearing adsorbed ODN at pH 5, 10 mM ionic strength with a borate buffer 10 mM, pH 9.2 containing 1 wt Triton X-405 surfactant. In this case, the washing step was performed by removing and replacing 25 v v of the supernatant. The desorption yield was clearly affected compared to surfactant-free buffer...