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

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.

Antimicrobial cotton gauzes modified with poly(acrylic acid-co-maltodextrin) hydrogel using chitosan as crosslinker

Cotton gauzes were grafted with a hydrogel of maltodextrin (MD) and poly(acrylic acid) (PAAc) using N-maleyl chitosan as crosslinker to obtain materials with antimicrobial properties. Reaction parameters including monomer, crosslinker, and initiator concentrations were studied. The modification with the copolymer poly(acrylic acid)-co-maltodextrin (PAAc-co-MD) was corroborated by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The grafted gauzes (gauze-g-(PAAc-co-MD)) were able to load vancomycin and inhibit the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. In addition, the incorporation of chitosan as crosslinker showed a synergistic effect against these bacteria. The prepared gauze-g-(PAAc-co-MD) materials could be used in the biomedical area particularly as antimicrobial wound dressings.

Utilization of biodegradable chitosan-derived sponges as oil retainers

An innovative approach of chitosan-derived biodegradable sponges with high sorption capacity, excellent recyclability, and inherent oleophilic properties have been developed for the first time to remove the crude oil polluting the environment. Chitosan-nitrogen mustard ionic carbonate-β-cyclodextrin (CH-NMIC-CD), chitosan-nitrogen mustard ionic carbonate (CH-NMIC), and chitosan (CH) sponges with macropores were prepared using tripolylphosphate (TPP) by adopting subsequent lyophilization. Detailed characterization such as FTIR, TGA, XRD, and SEM has been done to confirm the formation, stability, crystalline nature, and morphology of the prepared sponges. The FTIR spectra confirmed the successful incorporation of NMIC in CH-NMIC-CD and CH-NMIC and the presence of β-CD in the (CH-NMIC-CD). It was found from the TGA results that the presence of β-CD makes the sponge CH-NMIC-CD stable. SEM analysis showed the morphology of the sponges found to be highly porous with interconnected macropores. The oil absorption capacity was 12.30 g_oil/g_ns higher for the sponge CH-NMIC-CD followed by CH-NMIC and CH. The sponges showed reusability excellently even after consecutive sorption-desorption separation cycles for five times. Moreover, the sponges were completely biodegraded within 25 days. The finding holds a promising future to use CH-NMIC-CD sponges in pollutant entrapment particularly in the removal of crude oil and allied area.

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.

Chitosan reinforced hydrogels with swelling-shrinking behaviors in response to glucose concentration

Different hydrogels of poly(acrylamide-co-3-acrylamido phenylboronic acid-co-chitosan grafted maleic acid) (P(AM-co-AAPBA-co-CSMA)s) were synthesized using poly(ethylene glycol) diacrylate (PEGDA) as a crosslinker to serve for glucose sensing and insulin delivery. The structure and morphology of the hydrogels, named as CSPBA were studied by FTIR and SEM, while the mechanical properties were tested using dynamic mechanical analysis (DMA) and universal testing machine. The prepared hydrogels shrinked at low glucose concentration due to the 2:1 boronate-glucose binding, and swelled at high glucose concentration because of 1:1 boronate-glucose complexation. Both binding mechanisms are useful for glucose sensing and insulin delivery. The integration of CSMA into hydrogels network not only enhanced the response to glucose at physiological pH, but also improved the mechanical properties and increased the encapsulation efficiency of the prepared hydrogels. These CSPBA may find potential as implantable hydrogels in applications were continuous glucose monitoring and controlled release is beneficial.

Novel chitosan-based pH-responsive lipid-polymer hybrid nanovesicles (OLA-LPHVs) for delivery of vancomycin against methicillin-resistant Staphylococcus aureus infections

The development of novel materials is necessary for adequate delivery of drugs to combat the Methicillin-resistant Staphylococcus aureus (MRSA) burden due to the limitations of conventional methods and challenges associated with antimicrobial resistance. Hence, this study aimed to synthesise a novel oleylamine based zwitterionic lipid (OLA) and explore its potential to formulate chitosan-based pH-responsive lipid-polymer hybrid nanovesicles (VM-OLA-LPHVs1) to deliver VM against MRSA. The OLA was synthesised, and the structure characterised by ¹H NMR, ¹³C NMR, FT-IR and HR-MS. The preliminary biocompatibility of OLA and VM-OLA-LPHVs1 was evaluated on HEK-293, A-549, MCF-7 and HepG-2 cell lines using in vitro cytotoxicity assay. The VM-OLA-LPHVs1 were formulated by ionic gelation method and characterised in order to determine the hydrodynamic diameter (D_H), morphology in vitro and in vivo antibacterial efficacy. The result of the in vitro cytotoxicity study revealed cell viability of above 75% in all cell lines when exposed to OLA and VM-OLA-LPHVs1, thus indicating their biosafety. The VM-OLA-LPHVs1 had a D_H, polydispersity index (PDI), and EE% of 198.0 ± 14.04 nm, 0.137 ± 0.02, and 45.61 ± 0.54% respectively at physiological pH, with surface-charge (ζ) switching from negative at pH 7.4 to positive at pH 6.0. The VM release from the VM-OLA-LPHVs1 was faster at pH 6.0 compared to physiological pH, with 97% release after 72-h. The VM-OLA-LPHVs1 had a lower minimum inhibitory concentration (MIC) value of 0.59 μg/mL at pH 6.0 compared to 2.39 μg/mL at pH 7.4, against MRSA with 52.9-fold antibacterial enhancement. The flow cytometry study revealed that VM-OLA-LPHVs1 had similar bactericidal efficacy on MRSA compared to bare VM, despite an 8-fold lower VM concentration in the nanovesicles. Additionally, fluorescence microscopy study showed the ability of the VM-OLA-LPHVs1 to eliminate biofilms. The electrical conductivity, and protein/DNA concentration, increased and decreased respectively, as compared to bare VM which indicated greater MRSA membrane damage. The in vivo studies in a BALB/c mouse-infected skin model treated with VM-OLA-LPHVs1 revealed 95-fold lower MRSA burden compared to the group treated with bare VM. These findings suggest that OLA can be used as an effective novel material for complexation with biodegradable polymer chitosan (CHs) to form pH-responsive VM-OLA-LPHVs1 nanovesicles which show greater potential for enhancement and improvement of treatment of bacterial infections.

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.

DNA interaction, antitumor and antimicrobial activities of three-dimensional chitosan ring produced from the body segments of a diplopod

Commercially available chitins and the chitin isolated from mushrooms, insect cuticles, shells of shrimp, crab and crayfish reported in the literature are in forms of powder, flake or granule. Three-dimensional chitins have been only known from the sponges but still three-dimensional chitosan has not been reported yet. In this study, we produced three-dimensional chitin and chitosan rings from the body segments of a diplopod species (Julus terrestris). Obtained chitin and chitosan rings were characterized (by FT-IR, SEM, TGA, XRD, dilute solution viscometry and EA) and compared with commercial chitin and chitosan. The interactions with plasmid DNA was studied at varying concentrations of chitosan (0.04, 0.4 and 4mg/mL). Antitumor activity tests were conducted (L929 and HeLa), low cytotoxicity and high antiproliferative activity was observed. Antimicrobial activities of J. terrestris chitosan were investigated on twelve microorganisms and maximum inhibition (15.6±1.154mm) was recorded for common human pathogen Staphylococcus aureus.

Optimization, isotherm, kinetic and thermodynamic studies of Pb(II) ions adsorption onto N-maleated chitosan-immobilized TiO₂ nanoparticles from aqueous media

Chitosan, CS was chemically engineered by maleic anhydride via simple protocol to produce N-maleated chitosan, MCS which immobilized on anatase TiO2 to synthesize novel eco-friendly nanosorbent (51±3.8 nm), MCS@TiO2 for cost-effective and efficient removal of Pb(II) ions from aqueous media. The chemical structure, surface properties and morphology of MCS@TiO2 were recognized by FTIR, (1)H NMR, XRD, TEM, DLS and zeta-potential techniques. The relations between %removal of Pb(II) and different analytical parameters such as solution acidity (pH), MCS@TiO2 dosage, time of contact and initial Pb(II) concentration were optimized using response surface methodology (RSM) and Box-Behnken design (BBD) statistical procedures. The fitting of the experimental data to four different isotherm models at optimized conditions was carried out by various statistical treatments including the correlation coefficient (r), coefficient of determination (r(2)) and non-linear Chi-square (χ(2)) test analyses which all confirm the suitability of Langmuir model to explain the adsorption isotherm data. Also, statistics predicted that the pseudo-second-order model is the optimum kinetic model among four applied kinetic models to closely describe the rate equation of the adsorption process. Thermodynamics viewed the adsorption as endothermic and feasible physical process. EDTA could release the sorbed Pb(II) ions from MCS@TiO2 with a recovery above 92% after three sorption-desorption cycles. The novel synthesized nanosorbent is evidenced to be an excellent solid phase extractor for Pb(II) ions from wastewaters.

Nanocomplexes from RGD-modified generation 1.0 polyamidoamine based copolymers used for intravascular gene release to prevent restenosis

Aim: To validate the efficacy of nanocomplexes from RGD-modified polyamidoamine (PAMAM G1) copolymer for prevention of restenosis. Materials & methods: Generation 1.0 polyamidoamine (PAMAM G1)-based copolymers (PGP) and RGD modified PGP (PGP-RGD) were synthesized and its properties were evaluated. Intravascular VEGF165 release tests were performed. Results: The PGP-RGD1 (2.6% grafting rate) exhibited lower cytotoxicity and larger combining ability with pDNA. The complexes had sizes of 80–160 nm and zeta potentials of 3–20 mV. Transfection efficiency of PGP-RGD1 complexes in human umbilical vein endothelial cells was larger than that of PGP complexes. Patency and expression level of artery in PGP-RGD1 group were higher than that in saline group. Conclusion: PGP-RGD1 will be a promising targeted gene vector.

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.

A study on the hemocompatibility of dendronized chitosan derivatives in red blood cells

Dendrimers are hyperbranched macromolecules with well-defined topological structures and multivalent functionalization sites, but they may cause cytotoxicity due to the presence of cationic charge. Recently, we have introduced alkyne-terminated poly(amidoamine) (PAMAM) dendrons of different generations (G=2,3) into chitosan to obtain dendronized chitosan derivatives [Cs-g-PAMAM (G=2,3)], which exhibited a better water solubility and enhanced plasmid DNA transfection efficiency. In this study, we attempted to examine the impact of Cs-g-PAMAM (G=2,3) at different concentrations (25 μg/mL, 50 μg/mL, and 100 μg/mL) on the morphology, surface structure, and viability of rat red blood cells (RBCs). The results showed that treatment of RBCs with Cs-g-PAMAM (G=2,3) at 50 μg/mL and 100 μg/mL induced a slightly higher hemolysis than Cs, and Cs-g-PAMAM (G=3) caused a slightly higher hemolysis than Cs-g-PAMAM (G=2), but all values were <5.0%. Optical microscopic and atomic force microscopic examinations indicated that Cs-g-PAMAM (G=2,3) caused slight RBC aggregation and lysis. Treatment of RBCs with 100 μg/mL Cs-g-PAMAM (G=3) induced echinocytic transformation, and RBCs displayed characteristic irregular contour due to the folding of the periphery. Drephanocyte-like RBCs were observed when treated with 100 μg/mL Cs-g-PAMAM (G=3). Erythrocytes underwent similar shape transition upon treatment with Cs-g-PAMAM (G=2) or Cs. The roughness values (Rms) of RBCs incubated with Cs-g-PAMAM (G=2,3) were significantly larger than those for RBCs incubated with physiological saline (P<0.01), but the Rms showed no difference for Cs and Cs-g-PAMAM (G=2,3) (P>0.05). Furthermore, Cs-g-PAMAM (G=2,3) exhibited a lower cytotoxicity in human kidney 293T cells. These results indicate that Cs-g-PAMAM (G=2,3) are hemocompatible but may disturb membrane and lipid structures at higher concentrations. Further safety and biocompatibility evaluations are warranted for Cs-g-PAMAM. Our findings prove helpful for a better understanding of the advantages of combining PAMAM dendrimers and chitosan to design and develop new, safe, and effective drug delivery vehicles.

Enzyme multilayer coatings inhibit Pseudomonas aeruginosa biofilm formation on urinary catheters

Bacteria use a signaling mechanism called quorum sensing (QS) to form complex communities of surface-attached cells known as biofilms. This protective mode of growth allows them to resist antibiotic treatment and originates the majority of hospital-acquired infections. Emerging alternatives to control biofilm-associated infections and multidrug resistance development interfere with bacterial QS pathways, exerting less selective pressure on bacterial population. In this study, biologically stable coatings comprising the QS disrupting enzyme acylase were built on silicone urinary catheters using a layer-by-layer technique. This was achieved by the alternate deposition of negatively charged enzyme and positively charged polyethylenimine. The acylase-coated catheters efficiently quenched the QS in the biosensor strain Chromobacterium violaceum CECT 5999, demonstrated by approximately 50% inhibition of violacein production. These enzyme multilayer coatings significantly reduced the Pseudomonas aeruginosa ATCC 10145 biofilm formation under static and dynamic conditions in an in vitro catheterized bladder model. The quorum quenching enzyme coatings did not affect the viability of the human fibroblasts (BJ-5ta) over 7 days, corresponding to the extended useful life of urinary catheters. Such enzyme-based approach could be an alternative to the conventional antibiotic treatment for prevention of biofilm-associated urinary tract infections.

Dendron conjugation to graphene oxide using click chemistry for efficient gene delivery

Owing to its large surface area and rapid cellular uptake, graphene oxide (GO) is emerging as an attractive candidate material for delivery of drugs and genes.

A self-assembling polycationic nanocarrier that exhibits exceptional gene transfection efficiency

A novel polycationic gene carrier was prepared by conjugation of low molecular weight polyethyleneimine with gelatin through 4-bromonaphthaleic anhydride with exceptionally high transfection efficiency.

Dendronization of cellulose nanowhisker with cationic hyperbranched dendritic polyamidoamine

Polyamidoamine (PAMAM) dendrimers with active amino group up to the third generation were grafted onto the surface of cellulose nanocrystals (CNCs) by a divergent method. Cellulose nanowhiskers (CNW) are gaining interest as a "green" nanomaterial with exceptional chemical and mechanical properties for high-performance nanocomposite materials. Cellulose nanowhiskers are usually isolated from cotton by sulfuric acid hydrolysis and hydrochloric acid hydrolysis. The grafting of PAMAM dendrimer on CNW surface was monitored using FTIR, (1)H NMR, DLS and AFM. The results of FTIR and (1)H NMR confirmed the formation of PAMAM on the CNW. AFM images indicated the PAMAM synthesis on CNW through the nano-scale structures of macromolecules. The Zeta-potential value of polymer was found to be around +25 mV, and according to the collected data, the effective diameter of the CNW-g-PAMAM particles measured through DLS technique was found to be 73 nm.

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.