Carrier polymeric

The main purpose of pesticide formulation is to manufacture a product that has optimum biological efficiency, is convenient to use, and minimizes environmental impacts. The active ingredients are mixed with solvents, adjuvants (boosters), and fillers as necessary to achieve the desired formulation. The types of formulations include wettable powders, soluble concentrates, emulsion concentrates, oil-in-water emulsions, suspension concentrates, suspoemulsions, water-dispersible granules, dry granules, and controlled release, in which the active ingredient is released into the environment from a polymeric carrier, binder, absorbent, or encapsulant at a slow and effective rate. The formulation steps may generate air emissions, liquid effluents, and solid wastes. 

Off-resin analysis is analysis of a compound cleaved off a polymeric carrier material, usually in solution. 

Fu J, Fiegel J, Krauland E, and Hanes J. New polymeric carriers for controlled drug delivery following inhalation or injection [J]. Biomaterials, 2002, 23, 4425 1433. 

Release of a Protein from Its Polymeric Carrier during Transcytosis... 

Intracellular pathways after escape from the endolysosomal system into the cytosol are less clear. Obvious bottlenecks include, in the case of gene transfer (pDNA delivery), cytosolic transport to the perinuclear area, nuclear uptake, and nuclear presentation of the pDNA to the transcriptional machinery in bioactive form. In the case of siRNA (or mRNA and some other nucleic acids such as oligonucleotides), cytosolic accessibility for the required function is essential. Besides cytosolic transport [176, 177] and the nuclear import of large nucleic acid molecules [178-180], incorporation of functional nuclear import peptide domains has been evaluated [181-186]. Another bottleneck, nucleic acid unpackaging [187], i.e., partial or complete dissociation from the polymeric carrier, which is required for biological accessibility of the delivered nucleic acid, will be discussed in Sect. 3.3. 

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... 

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... 

Attempts to increase delivery of oligos into the cell mainly centre on the use of suitable carrier systems. Liposomes, as well as polymeric carriers (e.g. polylysine-based carriers), are gaining most attention in this regard. Details of such carriers have already been discussed earlier in this chapter. 

Espuelas MS, et al. Polymeric carriers for amphotericin B in vitro activity, toxicity and therapeutic efficacy against systemic candidiasis in neutropenic mice. J Antimicrob Chemother 2003 52 419. 

Furthermore, the polymeric carrier must be robust enough to withstand the reaction conditions used in solution-phase synthesis. Consequently, most soluble... 

Soluble polymers that have been used in hquid-phase methodologies are listed in Fig. 5.1 [3, 7, 8, 34, 35]. Polyethylene glycol and non-cross-linked polystyrene are some of the most often used polymeric carriers for organic synthesis and have found frequent use in the preparation of soluble polymer-supported catalysts and reagents consequently, a brief discussion of these polymers is warranted. 

Following this cleavage in principle, amines (bound as urethanes), alcohols (bound as carbonates), and carboxylic acids (bound as esters) can be detached from the polymeric carrier. The substrate specificity of the enzyme guarantees that only the intended ester is cleaved. 

Biological principles are also used in enzyme electrodes, where the sensor (usually an ion-selective electrode) is covered by a polymeric carrier containing an enzyme [32]. The determinand reacts in the enzyme layer yielding a product that causes a signal in the sensor. The bacterium electrode is based on a similar principle [84], as are electrodes using tissue in place of the enzyme layer [2]. 

Figure 1.3. Structure of PKl (HPMA copolymer doxorubicin), a 28-kDa polymeric carrier-drug conjugate investigated for its anti-tumour activity in a phase I clinical study. Adapted from reference [15].

Microspheres and nanoparticles often consist of biocompatible polymers and belong either to the soluble or the particle type carriers. Besides the aforementioned HPMA polymeric backbone, carriers have also been prepared using dextrans, ficoll, sepharose or poly-L-lysine as the main carrier body. More recently alginate nanoparticles have been described for the targeting of antisense oligonucleotides [28]. As with other polymeric carrier systems, the backbone can be modified with e.g. sugar molecules or antibody fragments to introduce cellular specificity. 

There is a current tendency to develop carriers on the basis of polypeptides and other polymeric carriers with rather simple structures. For instance, polylysines, polyhydrox-ymethyl-acrylamide and polylactic add material with variations in charge and molecular weight can be tailor-made and equipped with clustered recognition sites. The biocompatibility of such carrier systems with chronic dosing should, however, be more clearly established. 

Fig. 2. A schematic design of a targetable polymeric conjugate. Drug and targeting moiety are bound to the soluble polymeric carrier via a spacer...

Polymeric Carrier Drug Type of Bond Targeting Moiety Type of Bond Activity in vitro Activity in vivo Ref. 

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