Effect of hydrophobic and hydrophilic additives on sol-gel transition and release behavior of timolol maleate from polycaprolactone-based hydrogel

Photothermal Conversion of Hydrogel-Based Biomaterial

Traditional energy from fossil fuels like petroleum and coal is limited and contributes to global environmental pollution and climate change. Developing sustainable and eco-friendly energy is crucial for addressing significant challenges such as climate change, energy dilemma and achieving the long-term development of human society. Biomass hydrogels, which are easily synthesized and modified, have diverse sources and can be designed for different applications. They are being extensively researched for their applications in artificial intelligence, flexible sensing, biomedicine, and food packaging. The article summarizes recent advances in the preparation and applications of biomass-based photothermal conversion hydrogels, discussing the light source, photothermal agents, matrix, and preparation methods in detail. It also explores the use of these hydrogels in seawater desalination, photothermal therapy, antibacterial agents, and light-activated materials, offering new ideas for developing sustainable, efficient, and advanced photothermal conversion biomass hydrogel materials. The article concludes with suggestions for future research, highlighting the challenges and prospects in this field and paving the way for developing of long-lasting, efficient energy materials.

Combination chemotherapy against colorectal cancer cells: Co-delivery of capecitabine and pioglitazone hydrochloride by polycaprolactone-polyethylene glycol carriers

BACKGROUND

Colorectal cancer causes numerous deaths despite many treatment options. Capecitabine (CAP) is the standard chemotherapy regimen for colorectal cancer, and pioglitazone hydrochloride (PGZ) for diabetic disease treatment. However, free drugs do not induce effective apoptosis. This work aims to co-encapsulate CAP and PGZ and evaluate cytotoxic and apoptotic effects on HCT-119, HT-29 colorectal cancer cells, and human umbilical vein endothelial cells (HUVECs).

METHOD

CAP, PGZ, and combination treatment nano-formulations were prepared by triblock (TB) (PCL-PEG-PCL) biodegradable copolymers to enhance drugs' bioavailability as anti-cancer agents. The Ultrasonic homogenization method was used for preparing nanoparticles. The physicochemical characteristics of nanoparticles were studied using 1H NMR, FTIR, DLS, and FESEM techniques. The zeta potential, entrapment efficiency, drug release, and storage stability were studied. Also, cell viability and apoptosis were examined by using MTT, acridine orange (AO), and propidium iodide (PI), respectively.

RESULT

The smaller hydrodynamic size (236.1 nm), polydispersity index (0.159), and zeta potential (-20.8 mV) were observed in nanoparticles. Nanoparticles revealed a proper formulation and storage stability at 25 °C than 4 °C in 90 days. The synergistic effect was observed in (CAP-PGZ)-loaded TB nanoparticles in HUVEC, HCT-116, and HT-29 cells. In (AO/PI) staining, the high percentage of apoptotic cells in the (CAP-PGZ)-loaded TB nanoparticles in HUVEC, HCT-116, and HT-29 were calculated as 78 %, 71.66 %, and 69.31 %, respectively.

CONCLUSION

The (CAP-PGZ)-loaded TB nanoparticles in this research offer an effective strategy for targeted combinational colorectal cancer therapy.

Synthesis and Characterization of Ciprofloxacin Loaded Star-Shaped Polycaprolactone-Polyethylene Glycol Hydrogels for Oral Delivery

The administration of poorly water-soluble drugs represents a relevant problem due to the low body fluids transport efficiency through hydrophilic hydrogels. Star-shaped co-polymers, i.e., amphiphilic polymers such as those with a hydrophobic core and a hydrophilic outer shell, can be used to improve weak interactions with drugs, with relevant benefits in terms of administration and controlled delivery. In this work, two different co-polymers, four-arm star-shaped PCL-PEG and six-arm star-shaped PCL-PEG, were synthesized via ring-opening polymerization to be loaded with ciprofloxacin. ¹H-NMR and FTIR analyses confirmed that PCL arms were successfully grafted to the mPEG backbone, while DSC analysis indicated similar crystallinity and melting point, ranging from 56 to 60 °C, independent of the different co-polymer architecture. Therefore, both star-shaped PCL-PEGs were investigated as cargo device for ciprofloxacin. No significant differences were observed in terms of drug entrapment efficiency (>95%) and drug release, characterized by a pronounced burst followed by a slow sustained release, only slightly affected by the co-polymer architecture. This result was also confirmed with curve fitting via the Korsmeyer-Peppas model. Lastly, good antibacterial properties and biocompatibility exhibited in both star-shaped PCL-PEG co-polymers suggest a promising use for oral delivery applications.

Fabrication and examination of polyorganophosphazene/polycaprolactone-based scaffold with degradation, in vitro and in vivo behaviors suitable for tissue engineering applications

The present study aimed to synthesis a proper scaffold consisting of hydroxylated polyphosphazene and polycaprolactone (PCL), focusing on its potential use in tissue engineering applications. The first grafting of PCL to poly(propylene glycol)phosphazene (PPGP) was performed via ROP of ε-caprolactone, whereas PPGP act as a multisite macroinitiator. The prepared poly(propylene glycol phosphazene)-graft-polycaprolactone (PPGP-g-PCL) were evaluated by essential tests, including NMR, FTIR, FESEM-EDS, TGA, DSC and contact angle measurement. The quantum calculations were performed to investigate molecular geometry and its energy, and HOMO and LUMO of PPGP-g-PCL in Materials Studio2017. MD simulations were applied to describe the interaction of the polymer on phospholipid membrane (POPC128b) in Material Studio2017. The C2C12 and L929 cells were used to probe the cell-surface interactions on synthetic polymers surfaces. Cells adhesion and proliferation onto scaffolds were evaluated using FESEM and MTT assay. In vitro analysis indicated enhanced cell adhesion, high proliferation rate, and excellent viability on scaffolds for both cell types. The polymer was further tested via intraperitoneal implantation in mice that showed no evidence of adverse inflammation and necrosis at the site of the scaffold implantation; in return, osteogenesis, new-formed bone and in vivo degradation of the scaffold were observed. Herein, in vitro and in vivo assessments confirm PPGP-g-PCL, as an appropriate scaffold for tissue engineering applications.

Polymer-based thermoresponsive hydrogels for controlled drug delivery

INTRODUCTION

controlled drug delivery through hydrogels is generally limited by the poor barrier that polymeric network can create to diffusion mechanism. Stimuli responsive polymers can help in this way guaranteeing that delivery can be sustained and finely controlled using an external stimulus.

AREA COVERED

this review provides an overview of recent studies about the use of temperature as an external stimulus able to work as an efficient new route of drug's administration. Thermoresponsive hydrogels are discussed and compared in terms of physical properties and mechanism of drug release considering their classification in intrinsically (formed by thermosensitive polymers) and non-intrinsically (polymers with thermosensitive moieties) hydrogels.

EXPERT OPINION

thermoresponsive hydrogels can be developed by using different polymers added or not with micro/nanoparticles of organic or inorganic origin. In both cases the final system represents an innovative way for the local and sustained drug delivery in a specific site of the body. In particular, it is possible to obtain an on-demand release of drug by applying a local increase of temperature to the system.

3D porous PCL-PEG-PCL / strontium, magnesium and boron multi-doped hydroxyapatite composite scaffolds for bone tissue engineering

Bioceramic/polymer composite systems have gained importance in treating hard tissue damages using bone tissue engineering (BTE). In this context, it was aimed to develop 3D porous composite PCL-PEG-PCL scaffolds containing different amounts of B, Sr and Mg multi-doped HA that can provide bone regeneration in the bone defect area and to investigate the effect of both the amount of inorganic phase and the porosity on the mechanical and the biological properties. B-Sr-Mg multi-doped HA and PCL-PEG-PCL copolymer were successfully synthesized. PCL-PEG-PCL composite scaffolds containing different amounts of hydroxyapatite (HA) (10% and 20 wt%) were produced with the desired porosity (50% and 60%) by compression-molding and particulate leaching method. The porosity of the scaffolds was determined between 47% and 59%. HA/PCL-PEG-PCL composite scaffolds were subjected to a 3-week degradation test and showed negligible (0.2-0.5%) degradation. The water uptake percentage of the composite scaffolds with 60% porosity was the highest among all groups. Presence of HA in the scaffolds improved the water adsorption and the mechanical properties. Compressive strength of the scaffolds was between 9.32 and 24.27 MPa and 20% 2Sr0.5BHA scaffolds were found to have the maximum compressive strength. Compressive strength of 50% porous samples was higher than that of 60% porous samples. In the relative cell viability (%) test, the highest viability was observed on the scaffolds with HA and 2Sr0.5BHA. The specific ALP activity level of the cells on the scaffolds containing 2Sr0.5BHA was significantly higher (2.6 times) than that of the control group. The amount of porosity did not make a significant difference in cellular response. It was concluded that PCL-PEG-PCL composite scaffolds with 2Sr0.5BHA have the potential to be used in BTE.

The potential impact of trigonelline loaded micelles on Nrf2 suppression to overcome oxaliplatin resistance in colon cancer cells

Nuclear factor erythroid 2-related factor 2 (Nrf2) has a pivotal role in promoting chemoresistance by regulation of antioxidants and detoxification enzymes. Trigonelline is one of the major alkaloids in raw coffee which has been recently introduced as potent inhibitor of Nrf2. This study investigated the role of trigonelline and trigonelline loaded micelles in Nrf2 inhibition to break down oxaliplatin resistance in colon cancer cells. The PCL-PEG-PCL and PLA-PCL-PEG-PCL-PLA copolymers and trigonelline loaded micelles were prepared and characterized for fourier transforms infrared (FTIR), hydrogen nuclear magnetic resonance (¹H-NMR), carbon nuclear magnetic resonance (¹³C-NMR) spectroscopy, particle size, zeta potential, scanning electron microscopy (SEM) and entrapment efficiency. Cell viability and apoptosis were evaluated by using MTT and flow cytometry assays, respectively. Nrf2, MRP1, NQO1, HO-1, Bax, and Bcl2 gene expressions were examined by qRT-PCR. Our results revealed that micelles had spherical shapes with narrow sizes and zeta potential indexes of - 9.06 ± 6.94 mV for trigonelline loaded 3Block and - 7.47 ± 6.08 mV for trigonelline loaded 5Block micelles. After Nrf2 inhibition by trigonelline, antioxidant response element (ARE) related gene expressions were decreased (p < 0.05) with a significantly higher impact by trigonelline loaded micelles (p < 0.05). Trigonelline loaded micelles also strongly decreased IC50 value of oxaliplatin in resistant colon cancer cells (p < 0.05). Furthermore, trigonelline loaded 5Block micelle increased oxaliplatin-induced apoptosis in a Nrf2/ARE dependent manner. Altogether, the current study suggests that delivery of trigonelline loaded micelles as potent Nrf2 inhibitors can be considered as a promising strategy to overcome oxaliplatin resistance in colon cancer patients.

Self-Assemblable Polymer Smart-Blocks for Temperature-Induced Injectable Hydrogel in Biomedical Applications

Self-assembled temperature-induced injectable hydrogels fabricated via self-assembly of polymer smart-blocks have been widely investigated as drug delivery systems and platforms for tissue regeneration. Polymer smart-blocks that can be self-assembly play an important role in fabrication of hydrogels because they can self-assemble to induce the gelation of their copolymer in aqueous solution. The self-assembly occurs in response to an external stimulus change, such as temperature, pH, glucose, ionic strength, light, magnetic field, electric field, or their combination, which results in property transformations like hydrophobicity, ionization, and conformational change. The self-assembly smart-block based copolymers exist as a solution in aqueous media at certain conditions that are suitable for mixing with bioactive molecules and/or cells. However, this solution turns into a hydrogel due to the self-assembly of the smart-blocks under exposure to an external stimulus change in vitro or injection into the living body for a controllable release of loaded bioactive molecules or serving as a biomaterial scaffold for tissue regeneration. This work reports current scenery in the development of these self-assembly smart-blocks for fabrication of temperature-induced injectable physically cross-linked hydrogels and their potential application as drug delivery systems and platforms for tissue engineering.

Novel nano-vehicle for delivery and efficiency of anticancer auraptene against colon cancer cells

The aim of this study is to devise, prepare and characterize nano encapsulated auraptene (AUR) and evaluate cytotoxic and apoptotic effects on HT-29 colon cancer cells. Herein, AUR nano formulations were prepared by triblock (PCL-PEG-PCL) and pentablock (PLA-PCL-PEG-PCL-PLA) biodegradable copolymers in order to increase AUR bioavailability as an anticancer agent. The preparation of nano particles (NPs) was done with rotor stator homogenization (RSH) and Ultrasonic homogenization (USH) methods. The physicochemical characteristics of prepared nanoparticles (NPs) were studied using HNMR, FTIR, GPC, DLS and SEM techniques. The smaller hydrodynamic size (110 nm) and polydispersity index (PDI: 0.288) as well as higher cellular uptake (89%) were observed in PB NPs rather than TB NPs. The highest cytotoxic and apoptotic effects were observed in AUR loaded PB NPs compared to AUR loaded TB NPs and free AUR obtained by MTT assay, cell cycle arrest, Annexin V-FITC, DAPI staining and RT-PCR techniques. Real time PCR results indicated that Bax /Bcl2 expression ratio as an apoptosis predicting criterion, in free AUR, AUR loaded TB and AUR loaded PB have increased 6, 9 and 13 times, respectively (p value < 0.05). In conclusion, using biodegradable nano-vehicles for sustained delivery of natural anti-cancer compounds may open new perspectives for treatment of cancer patients.

One-pot synthesis and lubricity of fluorescent carbon dots applied on PCL-PEG-PCL hydrogel

This work presents a method for one-pot synthesis of N-doped nanometer-size carbon dots, which can be assembled with thermosensitive poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) hydrogel to achieve slow-release lubricity. The typical property of this green production was studied by fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The photoluminescence of composite PCEC/CDs hydrogel and its released solutions were characterized by ultraviolet spectrum, and the rheological properties were tested by rotary rheometer. Tribological performance of the released solution from composite PCEC/CDs hydrogel was obtained to compare with PBS and pure CDs solution. The experimental results reveal that the CDs contain the chemical groups of N-H, C-OH/C-O-C and -COOH, etc. In addition, the diameter of the CDs is in the range of 6~8 nm. The phase transition behavior of PCEC/CDs hydrogel can be still kept and its viscoelasticity hydrogel is improved by approximatively 7%. Furthermore, friction coefficient of the released solution from composite PCEC/CDs hydrogel decreases by about 70% than that of PBS. Besides, the wear condition can be improved by a lubricating transfer film formed by released CDs. This novel strategy for slow-release application is valuable for drug delivery and bio-tribology.

Novel Pentablock Copolymers as Thermosensitive Self-Assembling Micelles for Ocular Drug Delivery

Many studies have focused on how drugs are formulated in the sol state at room temperature leading to the formation of in situ gel at eye temperature to provide a controlled drug release. Stimuli-responsive block copolymer hydrogels possess several advantages including uncomplicated drug formulation and ease of application, no organic solvent, protective environment for drugs, site-specificity, prolonged and localized drug delivery, lower systemic toxicity, and capability to deliver both hydrophobic and hydrophilic drugs. Self-assembling block copolymers (such as diblock, triblock, and pentablock copolymers) with large solubility variation between hydrophilic and hydrophobic segments are capable of making temperature-dependent micellar assembles, and with further increase in the temperature, of jellifying due to micellar aggregation. In general, molecular weight, hydrophobicity, and block arrangement have a significant effect on polymer crystallinity, micelle size, and in vitro drug release profile. The limitations of creature triblock copolymers as initial burst release can be largely avoided using micelles made of pentablock copolymers. Moreover, formulations based on pentablock copolymers can sustain drug release for a longer time. The present study aims to provide a concise overview of the initial and recent progresses in the design of hydrogel-based ocular drug delivery systems.

A biodegradable ocular implant for long-term suppression of intraocular pressure

Timolol maleate (TM) has been used for many years for the reduction of intraocular pressure (IOP) in glaucoma patients. However, the topical mode of administration (eyedrops) is far from optimal because of the issues of low bioavailability, high drug wastage, and lack of patient compliance. Suboptimal control of the IOP leads to disease progression and eventually to blindness. Ideally, TM is delivered to the patient so that its action is both localized and sustained for 3 months or more. In this work, we developed a subconjunctival TM microfilm for sustained, long-term delivery of TM to the eyes, using the biodegradable elastomer poly(lactide-co-caprolactone) (PLC). The copolymer is biocompatible and has flexibility and mechanical characteristics suitable for a patient-acceptable implant. Controlling the release of TM for 3 months is challenging, and this work describes how, by using a combination of multilayering and blending with poly(ethylene glycol) (PEG) copolymers, we were able to develop a TM-incorporated biodegradable film that can deliver TM at a therapeutic dose for 90 days in vitro. The data was further confirmed in a diseased primate model, with sustained IOP-lowering effects for 5 months with a single implant, with acceptable biocompatibility and partial degradation.

Reversible hydrophobic ion-paring complex strategy to minimize acylation of octreotide during long-term delivery from PLGA microparticles

Acylation of peptide has been reported for a number of peptides and proteins during release from polymers comprising of lactide and glycolide. We hypothesize that reversible hydrophobic ion-pairing (HIP) complex may minimize octreotide acylation during release. Sodium dodecyl sulfate (SDS), dextran sulfate A (DSA, Mw 9-20 kDa) and dextran sulfate B (DSB, Mw 36-50 kDa) were selected as ion-pairing agents to prepare reversible HIP complex with octreotide. Complexation efficiency was optimized with respect to the mole ratio of ion-pairing agent to octreotide to achieve 100% complexation of octreotide. Dissociation studies suggested that DSA-octreotide and DSB-octreotide complexes dissociate completely at physiological pH in presence of counter ions unlike SDS-octreotide complex. DSA-octreotide and DSB-octreotide complex encapsulated PLGA microparticles (DSAMPs and DSBMPs) were prepared using the S/O/W emulsion method. Entrapment efficiencies for DSAMPs and DSBMPs were 74.7±8.4% and 81.7±6.3%, respectively. In vitro release of octreotide was performed by suspending MPs in gel. A large fraction of peptide was released in chemically intact form and <7% was acylated from DSAMPs and DSBMPs in gel over 55 days. Therefore, HIP complexation could be a viable strategy to minimize acylation of peptides and proteins during extended release from lactide and glycolide based polymers.

A heparin-mimicking reverse thermal gel for controlled delivery of positively charged proteins

Positively charged therapeutic proteins have been used extensively for biomedical applications. However, the safety and efficacy of proteins are mostly limited by their physical and chemical instability and short half-lives in physiological conditions. To this end, we created a heparin-mimicking sulfonated reverse thermal gel as a novel protein delivery system by sulfonation of a graft copolymer, poly(serinol hexamethylene urea)-co-poly(N-isopropylacylamide), or PSHU-NIPAAm. The net charge of the sulfonated PSHU-NIPAAm was negative due to the presence of sulfonate groups. The sulfonated PSHU-NIPAAm showed a typical temperature-dependent sol-gel phase transition, where polymer solutions turned to a physical gel at around 32°C and maintained gel status at body temperature. Both in vitro cytotoxicity tests using C2C12 myoblast cells and in vivo cytotoxicity tests by subcutaneous injections demonstrated excellent biocompatibility. In vitro release tests using bovine serum albumin revealed that the release from the sulfonated PSHU-NIPAAm was more sustained than that from the plain PSHU-NIPAAm. Furthermore, this sulfonated PSHU-NIPAAm system did not affect protein structure after 70-day observation periods.

Novel pentablock copolymer (PLA-PCL-PEG-PCL-PLA) based nanoparticles for controlled drug delivery: Effect of copolymer compositions on the crystallinity of copolymers and in vitro drug release profile from nanoparticles

The purpose of this investigation was to design novel pentablock copolymers (polylatide-polycaprolactone-polyethylene glycol- polycaprolactone-polylatide) (PLA-PCL-PEG-PCL-PLA) to prepare nanoparticle formulations which provide continuous delivery of steroids over a longer duration with minimal burst effect. Another purpose was to evaluate the effect of poly (L-lactide) (PLLA) or poly (D, L-lactide) (PDLLA) incorporation on crystallinity of pentablock copolymers and in vitro release profile of triamcinolone acetonide (selected as model drug) from nanoparticles. PLA-PCL-PEG-PCL-PLA copolymers with different block ratio of PCL/PLA segment were synthesized. Release of triamcinolone acetonide from nanoparticles was significantly affected by crystallinity of the copolymers. Burst release of triamcinolone acetonide from nanoparticles was significantly minimized with incorporation of proper ratio of PDLLA in the existing triblock (PCL-PEG-PCL) copolymer. Moreover, pentablock copolymer based nanoparticles exhibited continuous release of triamcinolone acetonide. Pentablock copolymer based nanoparticles can be utilized to achieve continuous near zero-order delivery of corticosteroids from nanoparticles without any burst effect.