Biocompatible Hemostatic Sponge Exhibiting Broad-Spectrum Antibacterial Activity

Hemorrhage during accidents or surgery is a significant challenge that can contribute to mortality. This is further aggravated due to bacterial infections at the injured site. Therefore, rapid application of a hemostatic and antibacterial material is highly necessary as a pretreatment for patients' survival. Herein, we have developed a hemostatic sponge (Hemobac) through amide crosslinking of gelatin and an N-(2-hydroxy) propyl-3-trimethylammonium chitosan (HTCC)-silver chloride nanocomposite (QAm₁-Ag_0.1) to mitigate bacterial infections, while aiding hemostasis. This Hemobac sponge completely eradicated (∼4-5 log) a wide range of Gram-positive and Gram-negative bacteria encompassing various clinical isolates within 6 h. The antihemorrhagic ability of Hemobac was ascertained through SEM images, which exhibited the presence of agglomerated blood cells onto the sponge with a significantly low blood-clotting index value (∼23 ± 1). Notably, Hemobac reduced the blood loss by ∼70-80% in the liver puncture model and femoral vein injury model in mice, displaying its improved hemostatic ability over a marketed gelatin-based sponge. Negligible hemolytic activity (∼6%) and retained healthy morphology of mammalian cells were observed upon exposure to the Hemobac sponge. Minimal immune response was noticed at the Hemobac-treated wound in mice through histopathology analysis. Collectively, these findings indicate that this biocompatible Hemobac sponge can stop the bleeding instantaneously and combat bacterial infections.

Temperature-mediated molecular ladder self-assembly employing Diels–Alder cycloaddition

Thermal annealing of sequence-defined, maleimide- and furan-bearing oligomers enables sequence-selective hybridization to afford molecular ladders incorporating Diels–Alder adduct-based rungs.

Barbiturate derived amphiphilic homopolymers: synthesis, characterization, self-assembly and anticancer drug delivery

Aim: Our aim was to synthesis and characterization of amphiphilic norbornene-derived thiobarbiturate homopolymers (NDTH 1-4) for drug delivery. Methods: Ring-opening metathesis polymerization technique was used to prepare a series of homopolymers. The hydrophobicity is introduced by increasing the number of carbon chains ([-CH₂-]_n; n = 1, 2, 3 & 4) in between norbornene backbone and thiobarbiturate species. Results: These vesicular aggregates have been used as anticancer Doxorubicin drug delivery vehicles at the acidic (5.5) and physiological (7.4) pHs. Confocal laser-scanning microscopy has demonstrated that the drug-loaded vesicles are easily internalized into living cells. Conclusion: Amphiphilic norbornene-derived thiobarbiturate homopolymer assemblies showed efficient nanocarrier for effective anticancer drug delivery.

Remarkable Reactivity of Boron-Substituted Furans in the Diels-Alder Reactions with Maleic Anhydride

The reactivity of boron-substituted furans as dienes in the Diels-Alder reaction with maleic anhydride has been investigated. Gratifyingly, the furans with boryl substituents at C-3 gave the exo cycloadduct exclusively with excellent yields. In particular, the potassium trifluoroborate exhibited outstanding reactivity at room temperature. Theoretical calculations suggested that the trifluoroborate group is highly activating and also that the thermodynamics is the main factor that determines whether the products can be obtained efficiently or not.

Dopamine-assisted fixation of drug-loaded polymeric multilayers to osteoarticular implants for tuberculosis therapy

Currently, the major issues in the treatment of osteoarticular tuberculosis (TB) after implant placement are low drug concentration at the infected focus and drug resistance resulting from the long-term chemotherapy. The application of drug-loaded polymeric multilayers on implantable devices offers a promising solution to the problems. Herein, a poly(ethylene glycol)-based hydrogel film embedded with isoniazid (INH)-loaded alginate microparticles was fixed to Ti implants via adhesive polydopamine, subsequently capped by poly(lactic-co-glycolic acid) membranes for the sustained and localized delivery of the anti-TB drug. The antibacterial efficacy of the released INH was confirmed by a 4.5 ± 0.8 cm inhibition zone formed in the fourth week after inoculation of Mycobacterium tuberculosis. The INH-loaded Ti implants showed no toxicity to the osteoblast cell and provided a consistent drug release for nearly one week in vitro. The release profile in vivo showed a high local concentration and low systemic exposure. The local INH concentration could be kept higher than its minimum inhibitory concentration over a period of 8 weeks, which proves that it is a promising strategy to improve the severe osteoarticular TB treatment.

Synthesis of Norbornene Derived Helical Copolymer by Simple Molecular Marriage Approach to Produce Smart Nanocarrier

A novel library of norbornene derived helical copolymer has been synthesized through the coupling of two homopolymers via Molecular Marriage Approach. The helicity is governed by the non-covalent interactions like hydrogen bonding, π-π stacking and the influence of hydrophobic and hydrophilic motifs. The detailed characterization of the copolymer (Copoly 1) has been provided and the super structures are confirmed through dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The observed size of the aggregates was about 200 nm. The density functional theory (DFT) is favorably supported for the formation of proposed structure of Copoly 1. Circular dichroism (CD) measurement has confirmed the one handed helical structure of the copolymer. Reservoir capability of this pH responsive polymer (Copoly 1) to encapsulate anti-cancer drug doxorubicin (DOX) warrants its potential applications in the field of bio-medical sciences.

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.

Biodegradable Copolymer for Stimuli-Responsive Sustained Release of Doxorubicin

Pendent functionalization of biodegradable polymers provides unique importance in biological applications. In this work, we have synthesized a polymeric nanocarrier for the controlled release of the anticancer drug doxorubicin (DOXI). Inspired by the pH responsiveness of acylhydrazine bonds along with the interesting self-assembly behavior of amphiphilic copolymers, this report delineates the development of a PEG-SS-PCL-DOXI copolymer consisting of DOXI, PEG, and a caprolactone backbone. First, the inclusion of a PEG moiety in the copolymer helps to achieve biocompatibility and aqueous solubility as well as a prolonged circulation time of the nanocarrier. Second, an acid-sensitive acylhydrazine-based linkage is chosen to attach DOXI to trigger sustained drug release, whereas the inclusion of an enzymatically cleavable disulfide linkage in the backbone adds to the advantage of backbone biodegradability at the intracellular level.

Norbornene derived nanocarrier reduces isoniazid mediated liver toxicity: assessment in HepG2 cell line and zebrafish model

The aim of this study was to investigate the protective effect of the stimuli-responsive norbornene-based nanocarrier complex of isoniazid, compared to pure isoniazid, on liver cells, byin vivoandin vitromethods.

VR, Sathyan A, Shunmugam R. An efficient method to prepare a new class of regioregular graft copolymer via a click chemistry approach

Herein, we report the synthesis of a novel regioregular poly-norbornene anhydride-g-(3-hexyl thiophene) (PNBA-g-PHT) graft copolymer.

Increased bioavailability of rifampicin from stimuli-responsive smart nano carrier

Stimuli responsive polymeric nanocarrier (RCOP-2) functionalized with frontline antituberculosis drug (Rifampicin) is demonstrated for sustained release. Bioavailability of Rifampicin is taken care of by conjugating this drug through a acylhydrazine linker to the polymeric backbone. The poly(ethylene glycol) structural motif is introduced in the copolymer architecture for water solubility. Releasing retinal along with Rifampicin is hypothesized to reduce the risk of side effects due to Rifampicin. The self-assembly of RCOP-2, due to the amphiphilicity present in the copolymer, is explored in detail. The pH responsiveness of RCOP-2 is demonstrated in mild acidic environment as well as in cell lines. The 4T cell line, due to its acidic nature, shows time-dependent cellular internalization. On the basis of the results, our unique design is expected to provide an increased bioavalaibility of Rifampicin with reduced side effects. From the flow cytometry results on A549 cell lines, it is clear that the newly designed copolymer RCOP-2 can internalize efficiently and serve as an effective Rifampicin delivery system.

Stimuli responsive nanocarrier for an effective delivery of multi-frontline tuberculosis drugs

We prepare stimuli responsive polymeric nanocarrier, RCP-2 to demonstrate the high drug content as well as controlled release in a systematic manner.