Poly (glutamic acid)--an emerging biopolymer of commercial interest.
TL;DR: In this paper, the authors provide updated information on fermentative production of poly (γ-glutamic acid) by various bacterial strains and effect of fermentation conditions and media component on production of PGA in submerged as well as solid state fermentation.
About: This article is published in Bioresource Technology.The article was published on 2011-05-01. It has received 308 citations till now.
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TL;DR: This review mainly focuses on pH-sensitive nano-systems, including advances in drug delivery, mechanisms of drug release, and possible improvements in drug absorption, with the emphasis on recent research in this field.
837 citations
Cites background from "Poly (glutamic acid)--an emerging b..."
...In acidic conditions, these polymers are protonated and their backbones become relatively hydrophobic; in contrast, they are deprotonated at neutral or high pH and become hydrophilic (Bajaj and Singhal, 2011; Yue et al., 2009; Zignani et al., 2000)....
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TL;DR: The design, structure, emergent properties, and applications for these multicomponent assemblies are presented in order to illustrate the potential of these formulations as sophisticated next-generation bio-inspired materials.
Abstract: Self-assembled peptide nanostructures have been increasingly exploited as functional materials for applications in biomedicine and energy. The emergent properties of these nanomaterials determine the applications for which they can be exploited. It has recently been appreciated that nanomaterials composed of multicomponent coassembled peptides often display unique emergent properties that have the potential to dramatically expand the functional utility of peptide-based materials. This review presents recent efforts in the development of multicomponent peptide assemblies. The discussion includes multicomponent assemblies derived from short low molecular weight peptides, peptide amphiphiles, coiled coil peptides, collagen, and β-sheet peptides. The design, structure, emergent properties, and applications for these multicomponent assemblies are presented in order to illustrate the potential of these formulations as sophisticated next-generation bio-inspired materials.
224 citations
TL;DR: Various responsive modes triggered by the tumor microenvironment stimuli are expatiated on, recent advances in multistage nanoparticle systems, especially the multi-stimuli responsive delivery systems are introduced, and their functions, effects, and prospects are discussed.
Abstract: The development of traditional tumor-targeted drug delivery systems based on EPR effect and receptor-mediated endocytosis is very challenging probably because of the biological complexity of tumors as well as the limitations in the design of the functional nano-sized delivery systems. Recently, multistage drug delivery systems (Ms-DDS) triggered by various specific tumor microenvironment stimuli have emerged for tumor therapy and imaging. In response to the differences in the physiological blood circulation, tumor microenvironment, and intracellular environment, Ms-DDS can change their physicochemical properties (such as size, hydrophobicity, or zeta potential) to achieve deeper tumor penetration, enhanced cellular uptake, timely drug release, as well as effective endosomal escape. Based on these mechanisms, Ms-DDS could deliver maximum quantity of drugs to the therapeutic targets including tumor tissues, cells, and subcellular organelles and eventually exhibit the highest therapeutic efficacy. In this review, we expatiate on various responsive modes triggered by the tumor microenvironment stimuli, introduce recent advances in multistage nanoparticle systems, especially the multi-stimuli responsive delivery systems, and discuss their functions, effects, and prospects.
219 citations
TL;DR: This review discusses the state of the art in the rational design and construction of robust bacterial chassis for metabolic engineering, presenting key examples of bacterial species that have secured a place in industrial bioproduction.
Abstract: The last few years have witnessed an unprecedented increase in the number of novel bacterial species that hold potential to be used for metabolic engineering. Historically, however, only a handful of bacteria have attained the acceptance and widespread use that are needed to fulfil the needs of industrial bioproduction - and only for the synthesis of very few, structurally simple compounds. One of the reasons for this unfortunate circumstance has been the dearth of tools for targeted genome engineering of bacterial chassis, and, nowadays, synthetic biology is significantly helping to bridge such knowledge gap. Against this background, in this review, we discuss the state of the art in the rational design and construction of robust bacterial chassis for metabolic engineering, presenting key examples of bacterial species that have secured a place in industrial bioproduction. The emergence of novel bacterial chassis is also considered at the light of the unique properties of their physiology and metabolism, and the practical applications in which they are expected to outperform other microbial platforms. Emerging opportunities, essential strategies to enable successful development of industrial phenotypes, and major challenges in the field of bacterial chassis development are also discussed, outlining the solutions that contemporary synthetic biology-guided metabolic engineering offers to tackle these issues.
193 citations
TL;DR: This review will focus on the potential of pH-sensitive micells in tumor therapy, analyze four types of drug-loaded micelles and mechanisms of drug release and give an exhaustive collection of recent investigations.
178 citations
Cites background from "Poly (glutamic acid)--an emerging b..."
...…with carboxylic acid groups are commonly used as pH-sensitive polymers, such as poly (acrylic acid), poly (methacrylic acid) (PMAA), poly (2-ethyl acrylic acid) and poly (glutamic acid) (Bajaj and Singhal, 2011; Bersani et al., 2014; Ding et al., 2012; Kang et al., 2012; Yan and Gemeinhart, 2005)....
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...Anionic polymers with carboxylic acid groups are commonly used as pH-sensitive polymers, such as poly (acrylic acid), poly (methacrylic acid) (PMAA), poly (2-ethyl acrylic acid) and poly (glutamic acid) (Bajaj and Singhal, 2011; Bersani et al., 2014; Ding et al., 2012; Kang et al., 2012; Yan and Gemeinhart, 2005)....
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References
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TL;DR: In this article, the chemistry and biosynthesis of poly-(gamma-glutamic acid) (Gamma-PGA) produced by various strains of Bacillus are discussed.
554 citations
Journal Article•
TL;DR: Data suggest that in addition to its role as a carrier for selective delivery of paclitaxel to the tumor, PG-TXL exerts distinct pharmacological actions of its own that may contribute to its remarkable antitumor efficacy.
Abstract: Despite an intensive search, few water-soluble paclitaxel derivatives have been shown to have a therapeutic index superior to paclitaxel itself. We now report a water-soluble poly(l-glutamic acid)-paclitaxel conjugate (PG-TXL) that produces striking antitumor effects with diminished toxicity. A single i.v. injection of PG-TXL at its maximum tolerated dose (defined as that dose that produces a maximum 12–15% body weight loss within 2 weeks after a single i.v. injection) equivalent to 60 mg of paclitaxel/kg and at even a lower dose equivalent to 40 mg of paclitaxel/kg resulted in the disappearance of an established implanted 13762F mammary adenocarcinoma (mean size, 2000 mm 3 ) in rats. (An equivalent dose of PG-TXL is the amount of conjugate that contains the stated amount of paclitaxel.) Similarly, mice bearing syngeneic OCA-1 ovarian carcinoma (mean size, 500 mm 3 ) were tumor-free within 2 weeks after a single i.v. injection of the conjugate at a dose equivalent to 160 mg of paclitaxel/kg. The conjugate has little if any intrinsic tubulin polymerization activity in vitro and is > 20 times less potent in supporting the growth of a paclitaxel-dependent CHO mutant cell line. PG-TXL has a prolonged half-life in plasma and greater uptake in tumor as compared with paclitaxel. Furthermore, only a small amount of total radioactivity from PG-[ 3 H]TXL was recovered as free [ 3 H]paclitaxel in either the plasma or the tumor tissue within 144 h after drug injection. Histological studies of tumor tissues obtained from mice treated with PG-TXL show fewer apoptotic cells but more extensive tumor necrosis as compared with paclitaxel treatment. These data suggest that in addition to its role as a carrier for selective delivery of paclitaxel to the tumor, PG-TXL exerts distinct pharmacological actions of its own that may contribute to its remarkable antitumor efficacy.
400 citations
TL;DR: The anchoring of PGA to the bacterial surface is important for virulence and all cap genes are therefore potential targets for inhibitors specifically blocking PGA synthesis or anchorage.
Abstract: Poly-gamma-glutamate (PGA), a natural polymer, is synthesized by several bacteria (all Gram-positive), one archaea and one eukaryote. PGA has diverse biochemical properties, enabling it to play different roles, depending on the organism and its environment. Indeed, PGA allows bacteria to survive at high salt concentrations and may also be involved in virulence. The minimal gene sets required for PGA synthesis were recently defined. There are currently two nomenclatures depending on the PGA final status: cap, for 'capsule', when PGA is surface associated or pgs, for 'polyglutamate synthase', when PGA is released. The minimal gene sets contain four genes termed cap or pgs B, C, A and E. The PGA synthesis complex is membrane-anchored and uses glutamate and ATP as substrates. Schematically, the reaction may be divided into two steps, PGA synthesis and PGA transport through the membrane. PGA synthesis depends primarily on CapB-CapC (or PgsB-PgsC), whereas PGA transport requires the presence, or the addition, of CapA-CapE (or PgsAA-PgsE). The synthesis complex is probably responsible for the stereochemical specificity of PGA composition. Finally, PGA may be anchored to the bacterial surface or released. An additional enzyme is involved in this reaction: either CapD, a gamma-glutamyl-transpeptidase that catalyses anchorage of the PGA, or PgsS, a hydrolase that facilitates release. The anchoring of PGA to the bacterial surface is important for virulence. All cap genes are therefore potential targets for inhibitors specifically blocking PGA synthesis or anchorage.
318 citations
TL;DR: The comparison of the flocculating activity between the present biopolymers and a commercial lower molecular weight product showed that the biopolymer of the present study had much higher activity.
292 citations
TL;DR: In this article, gamma-poly(glutamic acid) (gamma-PGA), a hydrophilic and biodegradable polymer, was chosen to modify chitosan matrices to produce a gamma-PGAs/chitosans composite biomaterial.
229 citations