Nagendra Kalva | National Chemical Laboratory (NCL) (original) (raw)

Papers by Nagendra Kalva

Polymer, 2021

Abstract A series of poly(N-isopropylacrylamide)30-SS-block-(cyclic-poly(L-lysine)n)-block-SS-pol... more Abstract A series of poly(N-isopropylacrylamide)30-SS-block-(cyclic-poly(L-lysine)n)-block-SS-poly(N-isopropylacrylamide)30 (n = 10, 20, 30) synthetic polymer polypeptide bio-conjugates have been synthesized for enhanced chemo-photothermal therapy. A combination of reversible addition-fragmentation chain transfer polymerization, click cycloaddition reaction, and ring-opening polymerization of α-amino acid N-carboxyanhydrides is utilized in the synthesis of a tadpole-shaped block copolymer. All the copolymers are self-assembled to nanoparticles in aqueous solutions, which are stabilized using a terephthalaldehyde crosslinker with successfully encapsulating doxorubicin (DOX) and IR780 dye. The polymer nanomicelles exhibited excellent drug loading capacity and efficiency. The in vitro drug release profiles demonstrate that the maximum release of DOX is achieved in pH 5.0 at 42 °C, in the presence of a glutathione intracellular mimic environment. IR780 dye significantly induces photothermal cytotoxicity to HT29 colon cancer lines under near-infrared laser irradiation. The new two-tailed tadpole-shaped synthetic polymer polypeptide bioconjugates exhibiting potential chemo-photothermal therapeutic effect thus appear to be a promising platform for anticancer therapy.

Reactive and Functional Polymers, 2021

Abstract Polymeric micelles with simultaneous bioimaging, drug delivery monitoring, and effective... more Abstract Polymeric micelles with simultaneous bioimaging, drug delivery monitoring, and effective delivery of therapeutic agents to target sites have attracted increasing attention in cancer therapy. In this study, a new biodegradable, pH-responsive, aggregation-induced emission (AIE)-active polycarbonate brush-like polymer was developed by combining ring-opening polymerization with click reaction. The anticancer drug, doxorubicin (DOX), was covalently conjugated to the polymer backbone via acid-sensitive Schiff base linkage, resulting in the pH-sensitive controlled release of DOX. The prodrug polymer self-assembled into nanomicelles in an aqueous solution, as confirmed using dynamic light scattering and transmission electron microscopy. Fluorescence imaging results demonstrated that prodrug micelles could be traced owing to the AIE features of micelles. In vitro drug release studies showed that DOX release was faster in acidic conditions (pH 5.0), whereas only a minimal amount of DOX was released in a physiological environment (pH 7.4). In summary, these smart prodrug micelles could be promising candidates for simultaneous intracellular imaging and cancer therapy.

Macromolecular Bioscience, 2020

Photo/pH dual-responsive amphiphilic diblock copolymers with alkyne functionalized pendant o-nitr... more Photo/pH dual-responsive amphiphilic diblock copolymers with alkyne functionalized pendant o-nitrobenzyl ester group are synthesized using poly(ethylene glycol) as a macroinitiator. The pendant alkynes are functionalized as aldehyde groups by the azide-alkyne Huisgen cycloaddition. The anticancer drug doxorubicin (DOX) molecules are then covalently conjugated through acid-sensitive Schiff-base linkage. The resultant prodrug copolymers self-assemble into nanomicelles in aqueous solution. The prodrug nanomicelles have a well-defined morphology with an average size of 20-40 nm. The dual-stimuli are applied individually or simultaneously to study the release behavior of DOX. Under UV light irradiation, nanomicelles are disassembled due to the ONB ester photocleavage. The light-controlled DOX release behavior is demonstrated using fluorescence spectroscopy. Due to the pH-sensitive imine linkage the DOX molecules are released rapidly from the nanomicelles at the acidic pH of 5.0, whereas only minimal amount of DOX molecules is released at the pH of 7.4. The DOX release rate is tunable by applying the dual-stimuli simultaneously. In vitro studies against colon cancer cells demonstrate that the nanomicelles show the efficient cellular uptake and the intracellular DOX release, indicating that the newly designed copolymers with dual-stimuli-response have significant potential applications as a smart nanomedicine against cancer.

Journal of Materials Chemistry B, 2020

A poly(lysine)-synthetic polymer hybrid nanomicelles were fabricated as promising platform for ef... more A poly(lysine)-synthetic polymer hybrid nanomicelles were fabricated as promising platform for efficient tumor targeting and glutathione/pH/temperature-responsive anticancer drug delivery.

Reactive and Functional Polymers, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Polymer International, 2017

Amphiphilic temperature and photoresponsive linear-dendritic block copolymers comprising second g... more Amphiphilic temperature and photoresponsive linear-dendritic block copolymers comprising second generation acetonide-2,2-bis-methylolpropionic acid (bis-MPA)-based polyester dendron and linear poly(N-isopropyl acrylamide) (PNIPAM) linked by an azobenzene unit were synthesized using ATRP followed by click chemistry. Precursor linear PNIPAM was prepared from an azide-functionalized azobenzene containing ATRP initiator. Two polymers obtained by varying the chain length of PNIPAM block showed different morphologies and LCST values in aqueous solution. Complete change in morphology of the two polymers into large spherical aggregates and nanotubes, respectively, was observed upon heating the micellar solution above LCST. Azobenzene unit was found to undergo trans-cis photoisomerization in the assemblies and caused change in the microenvironment of encapsulated hydrophobic dye without any release. Acetonide groups on the dendron were This article is protected by copyright. All rights reserved. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

RSC Advances, 2016

Linear-dendritic copolymers show differential dye encapsulation and photoinduced dye release base... more Linear-dendritic copolymers show differential dye encapsulation and photoinduced dye release based on the number and positions of azobenzenes in the dendritic backbone as well as substituents on the dendron periphery.

Polymer Chemistry, 2015

A biocompatible linear-dendritic copolymer comprising photo and pH-cleavable groups at the juncti... more A biocompatible linear-dendritic copolymer comprising photo and pH-cleavable groups at the junction was synthesised and controlled release of drug into cells was demonstrated.

Macromolecular Chemistry and Physics, 2014

Hydrophobic dendrons based on different branching patterns, viz. 3,5-di-and 3,4,5-trisubstituted ... more Hydrophobic dendrons based on different branching patterns, viz. 3,5-di-and 3,4,5-trisubstituted phenyl rings, consist of the same backbone but exhibit different sizes, shapes, and hydrophobic densities. These dendrons are attached to poly(ethylene glycol) and the core properties of the copolymer micelles are investigated in tetrahydrofuran (THF)/water mixtures by neutron scattering. Two polymers with intermediate hydrophobicity are studied further with variations in the solvent composition and the temperature. The aggregation numbers for 3,4,5-based dendron copolymers are lower, with more THF molecules of solvation compared with the 3,5-based dendron copolymer, the difference being greater at higher generations due to different molecular shapes. The micellar core size increases in small steps with dendron size so that dye encapsulation is tuned.

Molecules, 2019

Smart nano-carriers have attained great significance in the biomedical field due to their versati... more Smart nano-carriers have attained great significance in the biomedical field due to their versatile and interesting designs with different functionalities. The initial stages of the development of nanocarriers mainly focused on the guest loading efficiency, biocompatibility of the host and the circulation time. Later the requirements of less side effects with more efficacy arose by attributing targetability and stimuli-responsive characteristics to nano-carriers along with their bio- compatibility. Researchers are utilizing many stimuli-responsive polymers for the better release of the guest molecules at the targeted sites. Among these, pH-triggered release achieves increasing importance because of the pH variation in different organ and cancer cells of acidic pH. This specific feature is utilized to release the guest molecules more precisely in the targeted site by designing polymers having specific functionality with the pH dependent morphology change characteristics. In this revi...

Nanoscale, 2020

The water-soluble PEG-PATU Ag2S QDs have been successfully prepared by one-pot method, which disp... more The water-soluble PEG-PATU Ag2S QDs have been successfully prepared by one-pot method, which display the favorable NIR-II fluorescence property for in vivo bioimaging.

Journal of the American Chemical Society, 2012

Glycopolypeptides (GPs) were synthesized by ring-opening polymerization of glycosylated N-carboxy... more Glycopolypeptides (GPs) were synthesized by ring-opening polymerization of glycosylated N-carboxyanhydride monomer and attached to hydrophobic dendrons at one chain end by "click" reaction to obtain amphiphilic anisotropic macromolecules. We show that by varying polypeptide chain length and dendron generation, an organogel was obtained in dimethylsulfoxide, while nanorods and micellar aggregates were observed in aqueous solutions. Assemblies in water were characterized by electron microscopy and dye encapsulation. Secondary structure of the GP chain was shown to affect the morphology, whereas the chain length of the poly(ethylene glycol) linker between the GP and dendron did not alter rod-like assemblies. Bioactive surface chemistry of these assemblies displaying carbohydrate groups was demonstrated by interaction of mannose-functionalized nanorods with ConA.

Polymer Chemistry, 2018

Enzyme-responsive phosphoramidate dendrimers were successfully synthesized and their surfaces wer... more Enzyme-responsive phosphoramidate dendrimers were successfully synthesized and their surfaces were modified with zwitterionic groups for cancer drug delivery.

Reactive and Functional Polymers

Macromolecular Bioscience

A linear-dendritic block copolymer with both photo-and pH-cleavable linkages at the junction betw... more A linear-dendritic block copolymer with both photo-and pH-cleavable linkages at the junction between the hydrophobic dendron and hydrophilic linear polymer was synthesised. The photocleavable o-nitro-benzyl group attached to alkyne was introduced at the focal point of polyester dendron and acid-degrad-able acetal linkage with terminal azide was introduced at one end of linear polyethylene glycol. The two segments were connected using click chemistry. The copolymer was found to self-assemble into micelle-like aggregates in dilute aqueous solution. Stimuli-responsive disassembly of the aggregates was studied by monitoring fluorescence emission of the encapsulated hydrophobic dye and dynamic light scattering (DLS). Products of acetal cleavage at acidic pH were analyzed by gel permeation chromatography and NMR spectroscopy. The photo and pH stimuli were applied separately as well as simultaneously to study the rate of dye release. The synergistic effect of the two stimuli on dye release was demonstrated and the non-cytotoxic nature of the polymer was shown using the MTT assay. Cell uptake of DOX-loaded micelles and photo-induced release of the drug resulting in significantly higher cyto-toxicity than by free DOX was demonstrated using MDA-MB-231 cells.