Highly Efficient Photoswitchable Smart Polymeric Nanovehicle for Gene and Anticancer Drug Delivery in Triple-Negative Breast Cancer.

Over the past few decades, there has been significant interest in smart drug delivery systems capable of carrying multiple drugs efficiently, particularly for treating genetic diseases such as cancer. Despite the development of various drug delivery systems, a safe and effective method for delivering both anticancer drugs and therapeutic genes for cancer therapy remains elusive. In this study, we describe the synthesis of a photoswitchable smart polymeric vehicle comprising a photoswitchable spiropyran moiety and an amino-acid-based cationic monomer-based block copolymer using reversible addition-fragmentation chain transfer (RAFT) polymerization. This system aims at diagnosing triple-negative breast cancer and subsequently delivering genes and anticancer agents. Triple-negative breast cancer patients have elevated concentrations of Cu2+ ions, making them excellent targets for diagnosis. The polymer can detect Cu2+ ions with a low limit of detection value of 9.06 nM. In vitro studies on doxorubicin drug release demonstrated sustained delivery at acidic pH level similar to the tumor environment. Furthermore, the polymer exhibited excellent blood compatibility even at the concentration as high as 500 µg/mL. Additionally, it displayed a high transfection efficiency of approximately 82 ± 5% in MDA-MB-231 triple-negative breast cancer cells at an N/P ratio of 50:1. It is observed that mitochondrial membrane depolarization and intracellular reactive oxygen species generation are responsible for apoptosis and the higher number of apoptotic cells, which occurred through the arrest of the G2/M phase of the cell cycle were observed. Therefore, the synthesized light-responsive cationic polymer may be an effective system for diagnosis, with an efficient anticancer drug and gene carrier for the treatment of triple-negative breast cancer in the future.

Superior gene transfection efficiency in triple negative breast cancer by RAFT-mediated amino acid-based cationic diblock copolymers.

To date, the synthesis of efficient and safe gene carriers with low toxicity and appreciable gene transfection efficiency has been the major hurdle associated with non-viral gene carriers. Herein, we synthesized three amino acid-based diblock copolymers comprising glycine-leucine, leucine-phenyl alanine and glycine-phenyl alanine group containing blocks. The synthesis of all the diblock copolymers was confirmed by FTIR, 1H NMR, DLS and GPC techniques. All the polymers showed a high positive zeta potential value that varies from 45 ± 1 mV to 56 ± 1 mV, and the hydrodynamic size of the polymers varies from 250 ± 8 to 303 ± 14 nm. The three polymers showed negligible cytotoxicity compared with PEI (25 kDa) for MDA-MB-231 and NKE cells. Among all other polymers, P(HGN)n-b-P(HPN)m exhibited the highest biocompatibility with ∼70% cell viability at a concentration of 200 µg mL-1. Hemolysis data revealed that among all three polymers, P(HGN)n-b-P(HPN)m exhibited the highest blood compatibility, while up to a high concentration of 200 µg mL-1, it showed a very negligible amount (∼18%) of hemolysis. Most importantly, excellent gene complexation capability and good protection of pDNA against enzymatic degradation were observed with all three diblock copolymers. Interestingly, P(HGN)n-b-P(HPN)m/pDNA complex showed the smallest particle size (∼15 nm) and highest positive zeta potential as observed from TEM micrographs and DLS analysis, which probably results significantly higher level of cellular uptake and hence the highest transfection efficiency (∼85%) against MDA-MB-231 cells. Therefore, the diblock copolymer P(HGN)n-b-P(HPN)m with superior gene transfection efficiency in triple negative breast cancer may be an efficient non-viral vector for successful TNBC therapy in the future.

In vivo biocompatible shape memory polyester derived from recycled polycarbonate e-waste for biomedical application.

From the last few decades, the usage of polycarbonate (PC) has tremendously increased due to its engineering properties such as outstanding mechanical strength, superior toughness, and good optical transparency. Owning to these properties, PC has widespread applications in the field of electronics, construction, data storage, automotive industry and subsequently resulted in an ever-increasing volume of post-consumer PC e-waste, which also increases the environmental pollution with time due to its nonbiodegradability nature. Therefore, recycling of PC has become a significant challenge throughout the globe. Herein, we first time reported synthesis of a family of low-cost biodegradable and biocompatible biopolymers using solvent and catalyst free melt polycondensation reaction of recycled PC e-waste derived monomer bis(hydroxyethyl ether) of bisphenol A (BHEEB) along with other renewable resources such as sebacic acid, citric acid and mannitol. The synthesis of the polyester was confirmed by FTIR spectroscopy, NMR spectroscopy, XRD and DSC. The mechanical properties and biodegradation behaviour of the polyester can be fine-tuned by simply varying the monomer feed ratio. In addition to that, the polyester demonstrated excellent shape memory property in ambient temperature along with outstanding recovery properties. In addition to this, the synthesized polyester showed exceptional in vitro and in vivo cytocompatibility as well as cell proliferation rate against mouse fibroblast cells (NIH-3 T3) and biocompatibility, respectively. Therefore, the novel polyesters derived from recycled PC e-waste may be potential resorbable biomaterial for tissue engineering applications in future.

Knoevenagel condensation triggered synthesis of dual-channel oxene based chemosensor: Discriminative spectrophotometric recognition of F-, CN- and HSO4- with breast cancer cell imaging, real sample analysis and molecular keypad lock applications.

A novel oxene based unusual sensory receptor (HyMa) has been synthesized via.Knoevenagel condensation triggered carbon-heteroatom (oxygen) intramolecular bond formation reaction at room temperature for discriminative detection of multi-analytes like HSO4-, CN- & F- by spectro-photometric alterations with profound selectivity with the detection limit of 38 ppb, 18 ppb & 94 ppb respectively. Examination of the sensing mechanism was exhaustively investigated through several spectroscopic means like 1H NMR, FT-IR, absorption and fluorescence spectra etc. In addition, quantum mechanical calculations like DFT and Loewdin spin population analyses also validated the rationality of the host-guest interaction. Apart from these, the reversible spectroscopic responses of HyMa towards F- and Al3+ can imitate several complex logic functions that in turn help in preparing molecular keypad lock. This molecular keypad lock has the potential to protect the confidential information at the molecular scale. Additionally, the MTT assay of HyMa showed low cytotoxicity and membrane permeability indicating its attractive capability for bio-imaging towards triple negative breast cancer. HyMa-coated test strips could also be employed towards on-site detection of these deadly contaminants via "Dip Stick" approach without help of any instrumentation. In addition, HyMa has also been exploited for quantitative determination of HSO4- from various real water samples. In a nutshell, detection of lethal contaminants like CN-, F- & HSO4- at ppb level with in vitro live cell imaging has been explored with proper photophysical characterisation and theoretical calculations with real field applications.

RAFT polymerization mediated core-shell supramolecular assembly of PEGMA-co-stearic acid block co-polymer for efficient anticancer drug delivery.

In this work, core-shell supramolecular assembly polymeric nano-architectures containing hydrophilic and hydrophobic segments were synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Herein, polyethylene glycol methyl ether methacrylate (PEGMA), and stearic acid were used to synthesize the poly(PEGMA) homopolymer and stearyl ethyl methacrylate (SEMA), respectively. Then, PEGMA and SEMA were polymerized through controlled RAFT polymerization to obtain the final diblock copolymer, poly(PEGMA-co-SEMA) (BCP). Model anticancer drug, doxorubicin (DOX) was loaded on BCPs. Interestingly, efficient DOX release was observed at acidic pH, similar to the cancerous environment pH level. Significant cellular uptake of DOX loaded BCP50 (BCP50-DOX) was observed in MDA-MB-231 triple negative breast cancer cells and resulted in a 35 fold increase in anticancer activity against MDA MB-231 cells compared to free DOX. Scanning electron microscopy (SEM) imaging confirmed the apoptosis mediated cellular death. These core-shell supramolecular assembly polymeric nano-architectures may be an efficient anti-cancer drug delivery system in the future.

Folic acid based carbon dot functionalized stearic acid-g-polyethyleneimine amphiphilic nanomicelle: Targeted drug delivery and imaging for triple negative breast cancer.

Development of advanced therapeutic modalities for the treatment of cancer are become a thirst area in the field of biomedical science now a day. Current therapeutic approaches to treat this fatal disease always refer to partial curability with unavoidable obstacles. Here, we have developed stearic-g-polyethyleneimine acid amphiphilic nanomicelle functionalized with folic acid-based carbon dots (CDs) for targeted anticancer drug (doxorubicin, DOX) delivery and concurrent bio-imaging for triple negative breast cancer (TNBC). Developed nanomicelle was characterized by FTIR, XRD, 1H NMR, fluorescence spectroscopy, TEM etc. Highest DOX release from the nanomicelle was observed at slightly acidic pH. It was also found that the nanomicelle can be successfully internalized by the MDA-MB-231 cells and able to inhibit cell proliferation. The IC50 value by free DOX against TNBC was around 10 µg/mL, whereas, DOX loaded CD functionalized stearic-g-polyethyleneimine (25 kDa) (DOX-CDSP-25) showed similar cytotoxicity on TNBC at the concentration of only 1.0 µg/mL, indicating the efficiency of the delivery system compared to that of free DOX. Scanning electron microscopy (SEM) analysis revealed the effect of DOX-CDSP-25 on MDA-MB-231 cellular morphology in 24 h. Along with, the fluorescence property offered by folic acid derived CD allowed CDSP-25 to be acted as a promising bio-imaging tool for TNBC.

Natural polysaccharide derived carbon dot based in situ facile green synthesis of silver nanoparticles: Synergistic effect on breast cancer.

Over the decades, several nanoparticles have been developed for biomedical applications, still facile green synthesis derived nanoparticles showed tremendous attraction due to avoid of toxic solvent, ease of synthesis and low cost. Here, facile one pot in situ green synthesis is reported to develop silver nanoparticles with the aid of natural polysaccharide presented in sweet lemon peel waste derived carbon dot (CD) acted as a reducing and stabilizing agent at room temperature. The synthesis of CD and CD based silver nanoparticles (CD@AgNPs) was characterized by FTIR, UV-vis spectroscopy, fluorescence spectrophotometer, XRD and TEM. CD@AgNPs exhibited excellent antimicrobial activity against E. coli at very low concentration of 5.0 µg/ml. Interestingly, CD showed selective cytotoxicity against MCF7 breast cancer cells with the IC50 of 10 µg/ml while CD@AgNPs demonstrated synergistic effect on cytotoxicity. It is found that the cells death of MCF7 cells mainly occurred through the up-regulation of intracellular reactive oxygen species (ROS). Therefore, the synthesized CD@AgNPs may show an efficient anticancer agent for targeted breast cancer therapy in future.

Low molecular weight polyethyleneimine conjugated guar gum for targeted gene delivery to triple negative breast cancer.

The study emphasized on the development of an efficient, receptor-targeted non-viral gene delivery vehicle for gene therapy of triple negative breast cancer (TNBC). Here, naturally abundant guar gum based non-viral carrier was developed through conjugating by low molecular weight polyethylenimine (LPEI) (GNP) using napthalic anhydride coupling agent and characterized them by FT-IR, 1H NMR, XRD and UV spectrophotometer. The carrier was found to be cytocompatible as revealed by MTT assay against MDA-MB-231 and HeLa cell lines and excellent blood compatibility till the concentration of 200 µg/ml. In addition to these, the carrier exhibited excellent gene binding capability and formed spherical shaped complexes. The carrier showed very high in vitro transfection efficiency in TNBC cell (MDA-MB-231) compared to lipofectamine 2000 (LF2k) which could be justified by its high buffering capacity. Therefore, GNP may be an attractive non-viral gene carrier for gene therapy of TNBC in future.

Supramolecular Assembly of Amino Acid Based Cationic Polymer for Efficient Gene Transfection Efficiency in Triple Negative Breast Cancer.

The success of gene therapy is enormously dependent on an efficient gene carrier, and in this context, cationic polymers still continue to play a major role particularly with respect to the safety issue compared to viral vectors. Developing an efficient gene carrier system having promising gene transfection efficiency with low toxicity is the foremost impediment associated with a nonviral carrier. Here, we explored amino acid based biocompatible polymers synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization where glycine (Gly), leucine (Leu), and phenyl alanine (Phe) amino acids were used as the pendent groups of the polymeric brushes. The presence of both a hydrophobic group (long chain aliphatic group associated with the RAFT agent) and hydrophilic amino groups was associated with the supramolecular assembly of the polymeric chain having hydrodynamic sizes within the range of 150-300 nm with a positive zeta potential of 30 ± 5 mV. All polymers showed very low toxicity and possessed >80% cell viability even at a very high concentration of 1000 µg/mL against both normal and cancerous cells. In addition to this, the polymers also showed excellent blood compatibility, and negligible hemolysis was observed at the concentration of 500 µg/mL. All polymers showed efficient DNA complexation capability as well as excellent protection of DNA against highly negatively charged surfactant and enzymatic digestion, although the efficiency was dependent on the N/P ratio of polymer/DNA complexes. Interestingly, the phenyl alanine moiety containing polymer brush P(HEMA-Phe-NH2) showed a hexagonal shaped nanoparticle after complexation with pDNA and consequently showed higher cellular uptake, resulting in a higher transfection efficiency in a triple negative breast cancer cell, the MDA-MB-231 cell. Therefore, the synthesized polymer containing an amino acid pendent group, especially the phenyl alanine moiety, may be a promising nonviral gene carrier system in gene therapy application in the future.

Biomedical Applications of Graphene Nanomaterials and Beyond.

Graphene nanomaterials have been considered as a novel class of nanomaterials that show exceptional structural, optical, thermal, electrical, and mechanical properties. As a consequence, it has been extensively studied in various fields including electronics, energy, catalysis, sensing, and biomedical fields. In the previous couple of years, a significant number of studies have been done on graphene-based nanomaterials, where it is utilized in a wide range of bioapplications that includes delivery of small molecule drugs/genes, biosensing, tissue engineering, bioimaging, and photothermal and photodynamic therapies because of its excellent aqueous processability, surface functionalizability, outstanding electrical and mechanical properties, tunable fluorescence properties, and surface-enhanced Raman scattering (SERS).Therefore, it is necessary to get detailed knowledge about it. In this review, we will highlight the various synthesis procedures of graphene family nanomaterials including graphene oxide (GO), reduced graphene oxide (rGO), and graphene quantum dots (GQDs) as well as their biomedical applications. We will also highlight the biocompatibity of graphene nanomaterials as well as its possible risk factors for bioapplications. In conclusion, we will outline the future perspective and current challenges of graphene nanomaterials for clinical applications.

Engineering a multi-biofunctional composite using poly(ethylenimine) decorated graphene oxide for bone tissue regeneration.

Toward preparing strong multi-biofunctional materials, poly(ethylenimine) (PEI) conjugated graphene oxide (GO_PEI) was synthesized using poly(acrylic acid) (PAA) as a spacer and incorporated in poly(ε-caprolactone) (PCL) at different fractions. GO_PEI significantly promoted the proliferation and formation of focal adhesions in human mesenchymal stem cells (hMSCs) on PCL. GO_PEI was highly potent in inducing stem cell osteogenesis leading to near doubling of alkaline phosphatase expression and mineralization over neat PCL with 5% filler content and was ≈50% better than GO. Remarkably, 5% GO_PEI was as potent as soluble osteoinductive factors. Increased adsorption of osteogenic factors due to the amine and oxygen containing functional groups on GO_PEI augment stem cell differentiation. GO_PEI was also highly efficient in imparting bactericidal activity with 85% reduction in counts of E. coli colonies compared to neat PCL at 5% filler content and was more than twice as efficient as GO. This may be attributed to the synergistic effect of the sharp edges of the particles along with the presence of the different chemical moieties. Thus, GO_PEI based polymer composites can be utilized to prepare bioactive resorbable biomaterials as an alternative to using labile biomolecules for fabricating orthopedic devices for fracture fixation and tissue engineering.

Modified chitosan encapsulated core-shell Ag Nps for superior antimicrobial and anticancer activity.

This investigation reports a one pot synthesis of silver nanoparticles (Ag Nps) using aqueous solution of chitosan-graft-poly(acrylamide) (Cts-g-PAAm) as a reducing agent and polyethylene glycol (PEG) as a stabilizing agent. The as synthesized Ag Nps was characterized by ultra violet-visible (UV-vis), Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. Field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that Ag Nps, which were stable upto more than 60 days, were spherical in shape and the particle size was in the range of 5-50 nm. Atomic force microscopy (AFM) image also supported the above obtained result. The prepared Ag Nps exhibited strong antimicrobial activity against different gram positive bacteria (Alkaliphilus, Bascillus substillis, Lysinibascillus) and gram negative bacteria (Enterobacter aerogenus, Vivbrio vulnificus and Escherichia coli) and haemolytic assay revealed its blood compatible nature. The synthesized Ag Nps showed significant cytotoxicity over human cervical HeLa cancer cells and it was found that the inhibitory concentration for 50% cell death (IC50) was 8 µg/ml.

Poly(ester amide)s from Soybean Oil for Modulated Release and Bone Regeneration.

Designing biomaterials for bone tissue regeneration that are also capable of eluting drugs is challenging. Poly(ester amide)s are known for their commendable mechanical properties, degradation, and cellular response. In this regard, development of new poly(ester amide)s becomes imperative to improve the quality of lives of people affected by bone disorders. In this framework, a family of novel soybean oil based biodegradable poly(ester amide)s was synthesized based on facile catalyst-free melt-condensation reaction. The structure of the polymers was confirmed by FTIR and (1)H -NMR, which indicated the formation of the ester and amide bonds along the polymer backbone. Thermal analysis revealed the amorphous nature of the polymers. Contact angle and swelling studies proved that the hydrophobic nature increased with increase in chain length of the diacids and decreased with increase in molar ratio of sebacic acid. Mechanical studies proved that Young's modulus decreased with decrease in chain lengths of the diacids and increase in molar ratio of sebacic acid. The in vitro hydrolytic degradation and dye release demonstrated that the degradation and release decreased with increase in chain lengths of the diacids and increased with increase in molar ratio of sebacic acid. The degradation followed first order kinetics and dye release followed Higuchi kinetics. In vitro cell studies showed no toxic effects of the polymers. Osteogenesis studies revealed that the polymers can be remarkably efficient because more than twice the amount of minerals were deposited on the polymer surfaces than on the tissue culture polystyrene surfaces. Thus, a family of novel poly(ester amide)s has been synthesized, characterized for controlled release and tissue engineering applications wherein the physical, degradation, and release kinetics can be tuned by varying the monomers and their molar ratios.

Biofunctionalized surface-modified silver nanoparticles for gene delivery.

Silver nanoparticles (AgNPs) find use in different biomedical applications including wound healing and cancer. We propose that the efficacy of the nanoparticles can be further augmented by using these particles for gene delivery applications. The objective of this work was to engineer biofunctionalized stable AgNPs with good DNA binding ability for efficient transfection and minimal toxicity. Herein, we report on the one-pot facile green synthesis of polyethylene glycol (PEG) stabilized chitosan-g-polyacrylamide modified AgNPs. The size of the PEG stabilized AgNPs was 38 ± 4 nm with a tighter size distribution compared to the unstabilized nanoparticles which showed bimodal distribution of particle sizes of 68 ± 5 nm and 7 ± 4 nm. To enhance the efficiency of gene transfection, the Arg-Gly-Asp-Ser (RGDS) peptide was immobilized on the silver nanoparticles. The transfection efficiency of AgNPs increased significantly after immobilization of the RGDS peptide reaching up to 42 ± 4% and 30 ± 3% in HeLa and A549 cells, respectively, and significantly higher than 34 ± 3% and 23 ± 2%, respectively, with the use of polyethyleneimine (25 kDa). These nanoparticles were found to induce minimal cellular toxicity. Differences in cellular uptake mechanisms with RGDS immobilization resulting in improved efficiency are elucidated. This study presents biofunctionalized AgNPs for potential use as efficient nonviral carriers for gene delivery with minimal cytotoxicity toward augmenting the therapeutic efficacy of AgNPs used in different biomedical products.

pH sensitive N-succinyl chitosan grafted polyacrylamide hydrogel for oral insulin delivery.

pH sensitive PAA/S-chitosan hydrogel was prepared using ammonium persulfate (APS) as an initiator and methylenebisacrylamide (MBA) as a crosslinker for oral insulin delivery. The synthesized copolymer was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) study; morphology was observed under scanning electron microscope (SEM). The PAA/S-chitosan with ∼ 38% of insulin loading efficiency (LE) and ∼ 76% of insulin encapsulation efficiency (EE), showed excellent pH sensitivity, retaining ∼ 26% of encapsulated insulin in acidic stomach pH 1.2 and releasing of ∼ 98% of insulin in the intestine (pH 7.4), providing a prolonged attachment with the intestinal tissue. The oral administration of insulin loaded PAA/S-chitosan hydrogel was successful in lowering the blood glucose level of diabetic mice. The bioavailability of insulin was ∼ 4.43%. Furthermore, no lethality or toxicity was documented after its peroral administration. Thus, PAA/S-chitosan hydrogel could serve as a promising oral insulin carrier in future.

PAMAM conjugated chitosan through naphthalimide moiety for enhanced gene transfection efficiency.

Development of efficient and safe gene carrier is the main hurdle for successful gene therapy till date. Poor water solubility and low transfection efficiency of chitosan are the main drawbacks to be efficient gene carrier for successful gene therapy. In this work, PAMAM conjugated chitosan was prepared through naphthalimide moiety by simple substitution reaction. The synthesis of the chitosan conjugates was confirmed by FTIR, (1)H NMR and XRD analyses. The conjugates showed enhanced DNA binding capability compared to that of unmodified chitosan. Moreover, the conjugates showed minimal cytotoxicity compared to that of polyethyleneimine (PEI, 25 kDa) and also showed good blood compatibility with negligible haemolysis. The transfection efficiency of the conjugate was significantly increased compared to that of unmodified chitosan and it also surpassed the transfection efficiency by PEI. Therefore, PAMAM conjugated chitosan can be used safely as alternate efficient gene delivery vector in gene therapy.

Preparation of low toxic fluorescent chitosan-graft-polyethyleneimine copolymer for gene carrier.

Fluorescent chitosan-graft-polyethyleneimine (PEI) copolymer was prepared by incorporating PEI molecule onto chitosan backbone through naphthalimide moiety by simple substitution reaction. 4-Bromo-1,8-naphthalic anhydride was used as fluorescent probe due to its strong fluorescence and good photo-stability property and the presence of a fine tunable bromide functional group in the naphthalimide ring, in this work. The copolymer was characterized by FTIR, elemental analysis and XRD. The fluorescence property of the copolymer was determined by UV-vis spectrometer and spectrofluorometer. The effects of pH and temperature on fluorescence property of the copolymer were also studied. The graft copolymer with degree of substitution 37.6 of PEI onto chitosan showed better complexation ability with DNA at comparatively low N/P (nitrogen to phosphate ratio) ratio 1.0 compared to that of chitosan (N/P ratio 2.0). The cytotoxicity of PEI largely decreased after grafting with chitosan and all the copolymers showed above 50% cell viability even at high polymer concentration (300 µg/mL). Therefore, the prepared fluorescent chitosan-graft-PEI copolymer may be used as a biological marker as well as drug or gene carrier with low toxicity.

Blood compatible N-maleyl chitosan-graft-PAMAM copolymer for enhanced gene transfection.

To improve transfection efficiency, we prepared N-maleyl chitosan-graft-polyamidoamine (NMCTS-graft-PAMAM) copolymer. Self-assembled NMCTS-graft-PAMAM/pDNA complexes were prepared by complex coacervation method at different N/P (nitrogen to phosphate ratio) ratios. The copolymer effectively formed complexes with pDNA at lower N/P ratio (N/P ratio 1.0) than that of unmodified chitosan (N/P ratio 2.0) and the complexes were spherical with particle size of 100-150 nm. The copolymer showed significant protection of DNA from nuclease attack with lower toxicity against HeLa cell. The copolymer also showed no noticeable hemolytic effects up to 10mg/mL indicating no detectable disturbance of the red blood cell membranes. The transfection efficiency of the copolymer was increased significantly compared to that of chitosan and reached up to 36±2% at N/P ratio 7.0 which was higher than that of PEI (30±3% at N/P ratio 10). Therefore, the copolymer may be a strong alternative candidate as effective nonviral vector.

Oral insulin delivery by self-assembled chitosan nanoparticles: in vitro and in vivo studies in diabetic animal model.

We have developed self-assembled chitosan/insulin nanoparticles for successful oral insulin delivery. The main purpose of our study is to prepare chitosan/insulin nanoparticles by self-assembly method, to characterize them and to evaluate their efficiency in vivo diabetic model. The size and morphology of the nanoparticles were analyzed by dynamic light scattering (DLS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The average particle size ranged from 200 to 550 nm, with almost spherical or sub spherical shape. An average insulin encapsulation within the nanoparticles was ~85%. In vitro release study showed that the nanoparticles were also efficient in retaining good amount of insulin in simulated gastric condition, while significant amount of insulin release was noticed in simulated intestinal condition. The oral administrations of chitosan/insulin nanoparticles were effective in lowering the blood glucose level of alloxan-induced diabetic mice. Thus, self-assembled chitosan/insulin nanoparticles show promising effects as potential insulin carrier system in animal models.

Preparation of low molecular weight N-maleated chitosan-graft-PAMAM copolymer for enhanced DNA complexation.

Low molecular weight N-maleated chitosan-graft-PAMAM (polyamidoamine) copolymer was prepared through N-maleated chitosan (NMC) by Michael type addition reaction to enhance its solubility in water as well as its cationic character for enhancement of DNA complexation. FTIR, (1)H NMR, XRD and GPC were used to characterize the graft copolymers. The copolymer showed better DNA complexation ability at low N/P ratio than that of chitosan due to increased surface charge density by the incorporation of PAMAM molecule on to chitosan backbone. The copolymer can effectively protect the DNA toward anionic surfactant. In vitro release study showed efficient DNA release occurred at physiological pH (pH 7.4). In vitro cell cytotoxicity test indicated toward less cytotoxicity of NMC-graft-PAMAM copolymers compared to that of 25 kDa PEI. Thus, the synthesized NMC-graft-PAMAM copolymers have great potential of finding application in drug and gene delivery.