Photocleavable Visible Light-Triggered Anthraquinone-Derived Water-Soluble Block Copolymer for Peroxynitrite Generation in Cancer Therapy

We report a facile stimuli-responsive strategy to generate reactive oxygen and nitrogen species (ROS and RNS) in the biological milieu from a photocleavable water-soluble block copolymer under visible light irradiation (427 nm, 2.25 mW/cm2). An anthraquinone-based water-soluble polymeric nitric oxide (NO) donor (BCPx-NO) is synthesized, which exhibits NO release in the range of 40-65 μM within 10 h of photoirradiation with a half-life of 30-103 min. Additionally, BCPx-NO produces peroxynitrite (ONOO-) and singlet oxygen (1O2) under photoirradiation. To understand the mechanism of NO release and photolysis of the functional group under blue light, we prepared a small-molecule anthraquinone-based N-nitrosamine (NOD). The cellular investigation of the effect of spatiotemporally controlled ONOO- and 1O2 generation from the NO donor polymeric nanoparticles in a triple negative breast adenocarcinoma (MDA-MB-231) under visible light irradiation (white light, 5.83 mW/cm2; total dose 31.5 J/cm2) showed an IC50 of 0.6 mg/mL. The stimuli-responsive strategy using a photolabile water-soluble block copolymer employed to generate ROS and RNS in a biological setting widens the horizon for their potential in cancer therapy.

Photostimulated Extended Nitric Oxide (NO) Release from Water-Soluble Block Copolymer to Enhance Antibacterial Activity

N-Nitrosamines are well established motifs to release nitric oxide (NO) under photoirradiation. Herein, a series of amphiphilic N-nitrosamine-based block copolymers (BCPx-NO) are developed to attain controlled NO release under photoirradiation (365 nm, 3.71 mW/cm2). The water-soluble BCPx-NO forms micellar architecture in aqueous medium and exhibits a sustained NO release of 92-160 μM within 11.5 h, which is 36.8-64.0% of the calculated value. To understand the NO release mechanism, a small molecular NO donor (NOD) resembling the NO releasing functional motif of BCPx-NO is synthesized, which displays a burst NO release in DMSO within 2.5 h. The radical nature of the released NO is confirmed by electron paramagnetic resonance (EPR) spectroscopy. The gradual NO release from micellar BCPx-NO enhances antibacterial activity over NOD and exhibits a superior bactericidal effect on Gram-positive Staphylococcus aureus. In relation to biomedical applications, this work offers a comprehensive insight into tuning light-triggered NO release to improve antibacterial activity.

Fabrication of hydrolase responsive diglycerol based Gemini amphiphiles for dermal drug delivery applications

Since biocatalysts manoeuvre most of the physiological activities in living organisms and exhibit extreme selectivity and specificity, their use to trigger physicochemical change in polymeric architectures has been successfully used for targeted drug delivery. Our major interest is to develop lipase responsive nanoscale delivery systems from bio-compatible and biodegradable building blocks. Herein, we report the synthesis of four novel non-ionic Gemini amphiphiles using a chemo-enzymatic approach. A symmetrical diglycerol has been used as a core that is functionalised with alkyl chains for the creation of a hydrophobic cavity, and for aqueous solubility (polyethylene glycol) monomethyl ether (mPEG) is incorporated. Such systems can exhibit a varied self-assembly behaviour leading to the observance of different morphological structures. The aggregation behaviour of the synthesised nanocarrier was studied by dynamic light scattering (DLS) and critical aggregation concentration (CAC) measurements. The nanotransport potential of amphiphiles was investigated for hydrophobic guest molecules, i.e. Nile red, nimodipine and curcumin. Cytotoxicity of the amphiphiles was studied using HeLa and MCF7 cell lines at different concentrations, i.e. 0.05, 0.1, and 0.5 mg mL⁻¹. All nanocarriers were found to be non-cytotoxic up to a concentration of 0.1 mg mL⁻¹. Confocal laser scanning microscopy (cLSM) study suggested the uptake of encapsulated dye in the cytosol of the cancer cells within 4 h, thus implying that amphiphilic systems can efficiently transport hydrophobic drug molecules into cells. The biomedical application of the synthesised Gemini amphiphiles was also investigated for dermal drug delivery. In addition, the enzyme-mediated release study was performed that demonstrated 90% of the dye is released within three days. All these results supported the capability of nanocarriers in drug delivery systems.

Lipase responsive diglycerol based Gemini amphiphiles have been synthesized via a chemo-enzymatic approach and their application in dermal drug delivery has been explored.

Non-ionic PEG-oligoglycerol dendron conjugated nano-carriers for dermal drug delivery

A new class of non-ionic amphiphiles have been synthesised using a combination of polyethylene glycol (PEG) and oligoglycerol dendrons as hydrophilic units and an alkoxy aryl moiety as hydrophobic unit. The resulting amphiphiles were found to aggregate in aqueous medium. Their aggregation behaviour was studied using dynamic light scattering (DLS), fluorescence spectroscopy, and cryogenic electron microscopy (cryo-TEM). The inner hydrophobic core of these aggregates in aqueous medium is capable of encapsulating lipophilic guest molecules. The encapsulation behaviour was studied using Nile red as a hydrophobic dye as well as Curcumin and Dexamethasone as hydrophobic drug candidates. Furthermore, for biological evaluation, cytotoxicity and cellular uptake was studied using different cancer cell lines. The biomedical application of synthesised amphiphiles was further investigated for dermal drug delivery on excised human skin using Nile red encapsulated in the nanocarrier. The release profile of drug/dye encapsulated amphiphiles was studied under physiochemical conditions in the presence of immobilized lipase Novozym 435.

Stimuli-responsive non-ionic Gemini amphiphiles for drug delivery applications

This paper shows the synthesis of stimuli responsive Gemini amphiphiles sensitive to Glutathione and hydrolase.

One-Pot FDCA Diester Synthesis from Mucic Acid and Their Solvent-Free Regioselective Polytransesterification for Production of Glycerol-Based Furanic Polyesters

A one pot-two step procedure for the synthesis of diethyl furan-2,5-dicarboxylate (DEFDC) starting from mucic acid without isolation of the intermediate furan dicarboxylic acid (FDCA) was studied. Then, the production of three different kinds of furan-based polyesters— polyethylene-2,5-furan dicarboxylate (PEF), polyhydropropyl-2,5-furan dicarboxylate(PHPF) and polydiglycerol-2,5-furandicarboxylate (PDGF)—was realized through a Co(Ac)₂·4H₂O catalyzed polytransesterification performed at 160 °C between DEFDC and a defined diol furan-based prepolymer or pure diglycerol. In parallel to polymerization process, an unattended regioselective 1-OH acylation of glycerol by direct microwave-heated FDCA diester transesterification led to the formation of a symmetric prepolymer ready for further polymerization and clearly identified by 2D NMR sequences. Furthermore, the synthesis of a more soluble and hydrophilic diglycerol-based furanic polyester was also achieved. The resulting biobased polymers were characterized by NMR, FT-IR spectroscopy, DSC, TGA and XRD. The morphologies of the resulted polymers were observed by FE-SEM and the purity of the material by EDX.

Synthesis of non-ionic bolaamphiphiles and study of their self-assembly and transport behaviour for drug delivery applications

A series of four bolaamphiphiles with different hydrophilic units has been synthesised. All the amphiphiles were well characterised from their physiochemical data. The aggregation tendency of newly synthesised amphiphiles was studied using fluorescence spectroscopy, dynamic light scattering (DLS), and cryogenic electron microscopy (cryo-TEM). Furthermore, their application as nanocarriers for hydrophobic guests was demonstrated by using two established standards, i.e. the dye Nile red and the drug nimodipine. A cytotoxicity and cellular uptake study has been carried out using A549 cells. Due to the presence of an ester linkage in PEG based bolaamphiphiles, a drug release study was performed in the presence of an immobilized enzyme Novozym-435 (a lipase).

Fabrication of nanostructures through self-assembly of non-ionic amphiphiles for biomedical applications

Non-cytotoxic and non-ionic amphiphiles having supramolecular aggregation behavior were synthesized from biocompatible starting materials using a “greener” chemo-enzymatic method.

pH-Sensitive Nanoaggregates for Site-Specific Drug-Delivery as Well as Cancer Cell Imaging

Multifunctional polymeric nanoaggregates could enable targeted cancer therapy and imaging, which eventually facilitate monitoring of the therapeutic effect. A fluorescent nanoaggregate is constructed for theranostic application. Chlorambucil (Chl), a fluorescent inactive chemotherapeutic agent, is covalently attached to the nanoaggregate for therapeutic action. The pyrene (Py) motif is also covalently attached to the nanoaggregates, with the motivation of cancer cell imaging. This nanoaggregate is further functionalized with biotin (Btn) for receptor-mediated drug delivery. The efficiency of this system is evaluated by in vitro cell studies to prove its receptor-mediated internalization as well as theranostic capabilities. This newly designed nanocarrier, Nor-Chl-Py-Btn (Nor, norbornene), has the ability to combine both therapeutic and diagnostic capabilities into a single polymer that offers existing prospects for the development of nanomedicine.

Chemo-Enzymatic Synthesis of Perfluoroalkyl-Functionalized Dendronized Polymers as Cyto-Compatible Nanocarriers for Drug Delivery Applications

Among amphiphilic polymers with diverse skeletons, fluorinated architectures have attracted significant attention due to their unique property of segregation and self-assembly into discrete supramolecular entities. Herein, we have synthesized amphiphilic copolymers by grafting hydrophobic alkyl/perfluoroalkyl chains and hydrophilic polyglycerol [G2.0] dendrons onto a co-polymer scaffold, which itself was prepared by enzymatic polymerization of poly[ethylene glycol bis(carboxymethyl) ether]diethylester and 2-azidopropan-1,3-diol. The resulting fluorinated polymers and their alkyl chain analogs were then compared in terms of their supramolecular aggregation behavior, solubilization capacity, transport potential, and release profile using curcumin and dexamethasone drugs. The study of the release profile of encapsulated curcumin incubated with/without a hydrolase enzyme Candida antarctica lipase (CAL-B) suggested that the drug is better stabilized in perfluoroalkyl chain grafted polymeric nanostructures in the absence of enzyme for up to 12 days as compared to its alkyl chain analogs. Although both the fluorinated as well as non-fluorinated systems showed up to 90% release of curcumin in 12 days when incubated with lipase, a comparatively faster release was observed in the fluorinated polymers. Cell viability of HeLa cells up to 95% in aqueous solution of fluorinated polymers (100 μg/mL) demonstrated their excellent cyto-compatibility.

Chemo-Enzymatic Synthesis of Oligoglycerol Derivatives

A cleaner and greener method has been developed and used to synthesize 14 different functionalized oligomer derivatives of glycerol in moderate 29%–39% yields over three steps. After successive regioselective enzymatic acylation of the primary hydroxyl groups, etherification or esterification of the secondary hydroxyl groups and chemoselective enzymatic saponification, the target compounds can efficiently be used as versatile building blocks in organic and supramolecular chemistry.

Synthesis of macromolecular systems via lipase catalyzed biocatalytic reactions: applications and future perspectives

This review highlights the application of lipases in the synthesis of pharmaceutically important small molecules and polymers for diverse applications.

Easy directed assembly of only nonionic azoamphiphile builds up functional azovesicles

We reported that C₁₂OazoE₃OH is a functional molecule which directed assembly in water builds up into functional azovesicles.

Photoresponsive assemblies of linear-dendritic copolymers containing azobenzene in the dendron interior: the effect of the dendron structure on dye encapsulation and release

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.