Managing plastic packaging waste in emerging economies: The case of EPR in India.

India's large population, rapidly growing economy, and the consequent rising plastic waste, has necessitated the need for an efficient and effective plastic waste management (PWM) system for ensuring an environmentally cleaner and sustainable future. Consequently, PWM policy in India has recently undergone a substantial shift from being an informally organized, largely uncoordinated set of programs towards becoming a formal and integrated system based on the extended producer responsibility (EPR) approach. This paper explicates the evolution, development, implementation, and implications of the Indian EPR framework for PWM by developing an integrative mixed-method case study. Using a theory-based stakeholder evaluation model, the study critically analyzes the drivers and constraining factors from a multi-stakeholder perspective and provides prescriptive suggestions on EPR policy formulation and implementation. It highlights three themes i.e., (a) robust regulatory architecture; (b) operational mechanism; and (c) ecosystem catalysts, whose nature, dynamics, and practicality shall determine the future of the Indian EPR framework and those of comparable emerging economies.

Cross-linked polyethylenimine-hexametaphosphate nanoparticles to deliver nucleic acids therapeutics.

Branched polyethylenimine (PEI; 25 kDa) as a nonviral vector exhibits high transfection efficiency and is a potential candidate for efficient gene delivery. However, the cytotoxicity of PEI limits its application in vivo. PEI was ionically interacted with hexametaphosphate, a compact molecule with high anionic charge density, to obtain nanoparticles (PEI-HMP). Nanoparticles were assessed for their efficacy in protecting complexed DNA against nucleases. The intracellular trafficking of nanoparticles was monitored by confocal microscopy. The cytotoxicity and transfection efficiency of PEI-HMP nanoparticles were evaluated in vitro. In vitro transfection efficiency of PEI-HMP (7.7%) was approximately 1.3- to 6.4-folds higher than that of the commercial reagents GenePORTER 2, Fugene, and Superfect. Also, PEI-HMP (7.7%) delivered green fluorescent protein (GFP)-specific small interfering ribonucleic acid (siRNA) in culture cells leading to >80% suppression in GFP gene expression. PEI-HMP nanoparticles protected complexed DNA against DNase for at least 2 hours. A time-course uptake of PEI-HMP (7.7%) nanoparticles showed the internalization of nanoparticles inside the cell nucleus in 2 hours. Thus, PEI-HMP nanoparticles efficiently transfect cells with negligible cytotoxicity and show great promise as nonviral vectors for gene delivery. FROM THE CLINICAL EDITOR: Branched polyethylenimine (PEI) as a non-viral vector exhibits high transfection efficiency for gene delivery, but its cytotoxicity limits its applications. PEI hexametaphosphate nanoparticles (PEI-HMP) demonstrated a 1.3-6.4 folds higher transfection rate compared to commercial reagents. Overall, PEI-HMP nanoparticles efficiently transfect cells with negligible cytotoxicity and show great promise as non-viral vectors for gene delivery.

Unusually Large Brown tumor of Mandible in a Case of Secondary Hyperparathyroidism Mimicking Cherubism.

We report here a case of unusually large brown tumor of mandible mimicking cherubism in a patient with secondary hyperparathyroidism (HPT). The patient is a young male with a large head and a protruding jaw with an open mouth appearance. Initial clinical appearance looked like cherubism. However further clinical, biochemical, and radiological evaluation revealed a large brown tumor in a case of prolonged secondary HPT, which was confirmed on histopathology. All of the typical advanced radiological features of HPT were noted, highlighting the severity of progression of the disease. This case emphasizes the need for surveillance of serum calcium levels on routine biochemical investigations as to enable an early diagnosis of HPT. With timely proper management, such cases should be on the decline in the future.

Imidazolyl-PEI modified nanoparticles for enhanced gene delivery.

The derivatives of polyethylenimine (PEI 25 and 750kDa) were synthesized by partially substituting their amino groups with imidazolyl moieties. The series of imidazolyl-PEIs thus obtained were cross-linked with polyethylene glycol (PEG) to get imidazolyl-PEI-PEG nanoparticles (IPP). The component of hydrophobicity was introduced by grafting the lauryl groups in the maximal substituted IPP nanoparticles (IPPL). The nanoparticles were characterized with respect to DNA interaction, hydrodynamic diameter, zeta potential, in vitro cytotoxicity and transfection efficiency on model cell lines. The IPP and IPPL nanoparticles formed a loose complex with DNA compared to the corresponding native PEI, leading to more efficient unpackaging of DNA. The DNA loading capacity of IPP and IPPL nanoparticles was also lower compared to PEI. The imidazolyl substitution improved the gene delivery efficiency of PEI (750kDa) by nine- to ten-fold and PEI (25kDa) by three- to four-fold. At maximum transfection efficiency, the zeta potential of nanoparticles was positive after forming a complex with DNA. The maximum level of reporter gene expression was mediated by IPPL nanoparticles in both the series. The cytotoxicity, another pertinent problem with cationic polymers, was also negligible in case of IPP and IPPL nanoparticles.

PEI-alginate nanocomposites: efficient non-viral vectors for nucleic acids.

Branched polyethylenimine (PEI, 25 kDa) was ionically interacted with varying amount of alginic acid to block different proportion (2.6-5.7%) of amines in PEI to form a series of nanocomposites, PEI-Al. These nanocomposites, upon interaction with DNA, protected it against DNase I. Among various complexes evaluated, PEI-Al(4.8%)/DNA displayed the highest transfection efficiency in HEK293, COS-1 and HeLa cells that was approximately 2-8-folds higher than Superfect, Fugene, PEI (750 kDa)-Al(6.26%) and PEI alone. The projected nanocomposites were nearly non-toxic to cells in vitro. Furthermore, the concentration of PEI-Al(4.8%) needed to deliver GFP-specific siRNA in COS-1 cells was 20 times lower than PEI (750 kDa)-Al(6.26%). Intracellular trafficking of PEI-Al(4.8%) with or without complexed DNA in HeLa cells shows that both appear in the nucleus after 1 h.

Recent trends in non-viral vector-mediated gene delivery.

Nucleic acids-based next generation biopharmaceuticals (i.e., pDNA, oligonucleotides, short interfering RNA) are potential pioneering materials to cope with various incurable diseases. However, several biological barriers present a challenge for efficient gene delivery. On the other hand, developments in nanotechnology now offer numerous non-viral vectors that have been fabricated and found capable of transmitting the biopharmaceuticals into the cell and even into specific subcellular compartments like mitochondria. This overview illustrates cellular barriers and current status of non-viral gene vectors, i.e., lipoplexes, liposomes, polyplexes, and nanoparticles, to relocate therapeutic DNA-based nanomedicine into the target cell. Despite the awesome impact of physical methods (i.e., ultrasound, electroporation), chemical methods have been shown to accomplish high-level and safe transgene expression. Further comprehension of barriers and the mechanism of cellular uptake will facilitate development of nucleic acids-based nanotherapy for alleviation of various disorders.

Gene expression, biodistribution, and pharmacoscintigraphic evaluation of chondroitin sulfate-PEI nanoconstructs mediated tumor gene therapy.

Tumor-specific gene delivery constitutes a primary challenge in nonviral mediated gene therapy. In this investigation, branched polyethylenimine (bPEI, 25 kDa) was modified by forming nanoconstructs with a natural polysaccharide, chondroitin sulfate (CS), to impart site-specific property. A library of CS-PEI (CP) nanoconstructs was fabricated by altering the content of CS and evaluated in terms of size, surface charge, morphology, pDNA loading efficiency, pDNA release assay, pDNA protection study, cytotoxicity, and transfection efficiency. In vitro transfection efficiency of CP nanoconstructs was examined in HEK293, HEK293T, HepG2, and HeLa cell lines, while their cytotoxicity was investigated in HepG2 and HeLa cells. DNase I protection assay showed that the plasmid was protected from degradation over a period of time. The CP nanoconstructs possess significantly lower toxicity and enhanced transfection efficiency compared to PEI (25 kDa) and commercial transfection reagents (i.e., superfect, fugene, and GenePORTER 2). Further, the CP nanoconstructs were also found to transfect cells in serum-containing medium. In vivo studies were carried out with pDNA loaded CP-3 nanoconstruct after intravenous (iv) injection in Ehrlich ascites tumor (EAT)-bearing mice. The outcome revealed higher concentration of CP-3 nanoconstruct in tumor mass. These findings demonstrate that CP nanoconstructs could be exploited as carriers for nanomedicine for efficient management of solid tumor.

Efficient tumor targeting by polysaccharide decked polyethylenimine based nanocomposites.

Hyaluronic acid (HA)-polyethylenimine (PEI, 25 kDa) (HP) nanocomposites were fabricated for efficient targeting to solid tumors. Branched PEI was ionically blended with a natural mucopolysaccharide, HA, to partially block the positive charge and to impart site specificity to HP nanocomposites. A series of nanocomposites were prepared by varying the content of HA. HP nanocomposites were characterized by their size, morphology, zeta potential and evaluated for pDNA protection study, transfection efficiency and cytotoxicity. The competency of HP nanocomposites to relocate a plasmid encoding enhanced green fluorescent protein (pEGFP) gene was assessed in HEK293, HEK293T, and HeLa cells and found to be approximately 1-8 folds efficient compared to Superfect, Fugene, GenePORTER 2. HP nanocomposites also exhibited efficient transfection in serum-containing medium. MTT assay showed significantly improved cell viability in HEK293T, HepG2 and HeLa cells. The specificity of HP nanocomposites to target tumor was investigated in vivo by injecting pDNA-loaded HP-4 nanocomposite or PEI intravenously into mice bearing Ehrlich ascites tumor (EAT). The gamma scintigraphic studies showed a higher accumulation of HP-4 nanocomposite in the solid tumor compared to PEI. The results cumulatively advocate that HP nanocomposites could epitomize a viable alternative for site specific gene therapy.

A unique and highly efficient non-viral DNA/siRNA delivery system based on PEI-bisepoxide nanoparticles.

Delivery of DNA and siRNA into mammalian cells is a powerful technique in treating various diseases caused by single gene defects. Herein, we report a highly efficient delivery system using 1,4-butanediol diglycidyl ether (bisepoxide) crosslinked polyethylenimine (PEI) nanoparticles (PN). The nanoparticle/DNA complexes (nanoplexes) exibited approximately 2.5- to 5.0-fold gene transfer efficacy and decreased cytotoxicity in cultured cell lines, compared to the native PEI (25 kDa) (gold standard) and commercially available transfection agents such as Lipofectamine 2000 and Fugene. The bisepoxide crosslinking results in change in amine ratio in PEI; however, it retains the net charge on PN unaltered. A series of nanoparticles obtained by varying the degree of crosslinking was found to be in the size range of 69-77 nm and the zeta potential varying from +35 to 40 mV. The proposed system was also found to deliver siRNA efficiently into HEK cells, resulting in approximately 70% suppression of the targetted gene (GFP).

Engineered polyallylamine nanoparticles for efficient in vitro transfection.

PURPOSE: Cationic polymers (i.e. polyallylamine, poly-L-lysine) having primary amino groups are poor transfection agents and possess high cytotoxicity index when used without any chemical modification and usually entail specific receptor mediated endocytosis or lysosomotropic agents to execute efficient gene delivery. In this report, primary amino groups of polyallylamine (PAA, 17 kDa) were substituted with imidazolyl functions, which are presumed to enhance endosomal release, and thus enhance its gene delivery efficiency and eliminate the requirement of external lysosomotropic agents. Further, systems were cross-linked with polyethylene glycol (PEG) to prepare PAA-IAA-PEG (PIP) nanoparticles and evaluated them in various model cell lines. MATERIALS AND METHODS: The efficacy of PIP nanoparticles in delivering a plasmid encoding enhanced green fluorescent protein (EGFP) gene was assessed in COS-1, N2a and HEK293 cell lines, while their cytotoxicity was investigated in COS-1 and HEK293 cell lines. The PAA was chemically modified using imidazolyl moieties and ionically cross-linked with PEG to engineer nanoparticles. The extent of substitution was determined by ninhydrin method. The PIP nanoparticles were further characterized by measuring the particle size (dynamic light scattering and transmission electron microscopy), surface charge (zeta potential), DNA accessibility and buffering capacity. The cytotoxicity was examined using the MTT method. RESULTS: In vitro transfection efficiency of synthesized nanoparticles is increased up to several folds compared to native polymer even in the presence of serum, while maintaining the cell viability over 100% in COS-1 cells. Nanoparticles possess positive zeta potential between 5.6-13 mV and size range of 185-230 nm in water. The accessibility experiment demonstrated that nanoparticles with higher degree of imidazolyl substitution formed relatively loose complexes with DNA. An acid-base titration showed enhanced buffering capacity of modified PAA. CONCLUSIONS: The PIP nanoparticles reveal tremendous potential as novel delivery system for achieving improved transfection efficiency, while keeping the cells at ease.