New strategies for polymer development in pharmaceutical science--a short review

Evaluation of Anti-Candida albicans Activity and Release of Ketoconazole in PMMA-G-PEG 4000 Films

Modified release systems depend on the selection of an appropriate agent capable of controlling the release of the drug, sustaining the therapeutic action over time, and/or releasing the drug at the level of a particular tissue or target organ. Polyethylene glycol 4000 (PEG 4000) is commonly employed in drug release formulations while polymethyl methacrylate (PMMA) is non-toxic and has a good solubility in organic solvents. This study aimed at the incorporation of ketoconazole in PMMA-g-PEG 4000 and its derivatives, thus evaluating its release profile and anti-Candida albicans and cytotoxic activities. Ketoconazole was characterized and incorporated into the copolymers. The ketoconazole incorporated in the copolymer and its derivatives showed an immediate release profile. All copolymers with ketoconazole showed activity against Candida albicans and were non-toxic to human cells in the entire concentration tested.

Monitoring of microbiological dynamics in beach sand and seawater samples from recreational and non-recreational beaches over a two-year period

The frequencies of Escherichia coli, Staphylococcus aureus and Methicillin-resistant S. aureus (MRSA) and 'aerobic mesophilic bacteria' (AMB) counts in different seasons and marine sources were compared to understand the microbiological dynamics at beaches in N. Cyprus. Also, antibiotic resistance patterns were evaluated. The characterization and AMB enumeration studies were performed by conventional microbiological methods. AMB counts increased from winter to summer significantly (45.5*10⁴ CFU/mL to 2.5*10⁶ CFU/mL). Similarly, percentage detection frequencies of the bacteria were higher in summer compared to winter and were significant particularly for E. coli in both sand and seawater samples in 2019 and 2020 (p = 0.0181, p = 0.0142, p = 0.1257, p = 0.0446, respectively). However, a significant difference was not detected in percentage detection frequencies in terms of different sources or recreational status of beaches. The highest resistance percentages were detected against beta-lactam and lincosamides group of antibiotics. Results of the study signified that regular microbiological monitoring for beaches is essential.

Asymmetric flow field-flow fractionation (AF4) with fluorescence and multi-detector analysis for direct, real-time, size-resolved measurements of drug release from polymeric nanoparticles

Polymeric nanoparticles (NPs) are typically designed to enhance the efficiency of drug delivery by controlling the drug release rate. Hence, it is critical to obtain an accurate drug release profile. This study presents the first application of asymmetric flow field-flow fractionation (AF4) with fluorescence detection (FLD) to quantify release profiles of fluorescent drugs from polymeric NPs, specifically poly(lactic-co-glycolic acid) NPs loaded with enrofloxacin (PLGA-Enro NPs). In contrast to conventional measurements requiring separation of the NPs and dissolved drugs (typically by dialysis) prior to quantification, AF4 provides in situ removal of unincorporated drugs, while the judicious combination of online FLD and UV detection selectively provides the entrapped drug and PLGA NP concentrations, respectively, and hence the drug loading. NP size and shape factors are simultaneously obtained by online dynamic and multi-angle light scattering (DLS, MALS) detectors. The AF4 and dialysis approaches were compared to evaluate drug release from PLGA-Enro NPs containing a high proportion (≈ 94%) of unincorporated (burst release) drug at three temperatures spanning the glass transition temperature (T_g ≈ 33 °C) of the NPs. The AF4 method clearly captured the temperature dependence of the drug release relative to T_g (from no release at 20 °C to rapid release at 37 °C). In contrast, dialysis was not able to distinguish differences in the extent or rate of release of the entrapped drug because of interferences from the burst release, as well as the dialysis lag time, as supported through a diffusion model and validation experiments on purified NPs with low burst release. Finally, the multi-detector AF4 analysis yielded unique size-dependent release profiles across the entire NP size distribution, with smaller NPs showing faster release consistent with radial diffusion from the NPs. Overall, this study demonstrates the novel application and advantages of multi-detector AF4 methods, particularly AF4-FLD, to obtain direct, size-resolved release profiles of fluorescent drugs from polymeric NPs.

Connecting Gas-Phase Computational Chemistry to Condensed Phase Kinetic Modeling: The State-of-the-Art

In recent decades, quantum chemical calculations (QCC) have increased in accuracy, not only providing the ranking of chemical reactivities and energy barriers (e.g., for optimal selectivities) but also delivering more reliable equilibrium and (intrinsic/chemical) rate coefficients. This increased reliability of kinetic parameters is relevant to support the predictive character of kinetic modeling studies that are addressing actual concentration changes during chemical processes, taking into account competitive reactions and mixing heterogeneities. In the present contribution, guidelines are formulated on how to bridge the fields of computational chemistry and chemical kinetics. It is explained how condensed phase systems can be described based on conventional gas phase computational chemistry calculations. Case studies are included on polymerization kinetics, considering free and controlled radical polymerization, ionic polymerization, and polymer degradation. It is also illustrated how QCC can be directly linked to material properties.

Selective targeting of cancer signaling pathways with nanomedicines: challenges and progress

Cancer is one of the leading causes of death worldwide. Regardless of advances in understanding the molecular mechanics of cancer, its treatment is still lacking and the death rates for many forms of the disease remain the same as six decades ago. Although a variety of therapeutic agents and strategies have been reported, these therapies often failed to provide efficient therapy to patients as a consequence of the inability to deliver right and adequate chemotherapeutic agents to the right place. However, the situation has started to revolutionize substantially with the advent of novel 'targeted' nanocarrier-based cancer therapies. Such therapies hold great potential in cancer management as they are biocompatible, tailored to specific needs, tolerated and deliver enough drugs at the targeted site. Their use also enhances the delivery of chemotherapeutics by improving biodistribution, lowering toxicity, inhibiting degradation and increasing cellular uptake. However, in some instances, nonselective targeting is not enough and the inclusion of a ligand moiety is required to achieve tumor targeting and enhanced drug accumulation at the tumor site. This contemporary review outlines the targeting potential of nanocarriers, highlighting the essentiality of nanoparticles, tumor-associated molecular signaling pathways, and various biological and pathophysiological barriers.

Development of a Negative-Biased Zwitterionic Polypeptide-Based Nanodrug Vehicle for pH-Triggered Cellular Uptake and Accelerated Drug Release

Albumin mimics could be an attractive platform for nanodrug carriers through systematic administration because of high safety and plentiful properties to be adjusted for a high drug efficacy, such as pH-triggered targeting cellular uptake and drug release. In this work, negative-biased zwitterionic nanodrug carriers based on zwitterionic polypeptide chains that mimic albumin were prepared, which have an outermost layer of zwitterionic glutamic acid (E) and lysine (K) pairs with a small amount of aspartic acid (D) to adjust the overall ζ potential. On the other hand, doxorubicin (Dox) was encapsulated in a hydrophobic core by 11-maleimidoundecanoic acid covalently linked with additional cysteine (C) residues on the polypeptide. The results show that the negative-biased zwitterionic nanodrug carriers can sensitively enhance the cellular uptake in responding to a pH change from 7.4 to 6.7 without reversing the ζ potential to a positive charge, leading to accelerating the Dox release rate in a slightly acidic environment through the polypeptide secondary structure change. Moreover, the anionic nanodrug carrier can also be easily enzymatically digested by trypsin for quick drug release. In short, this negative-biased zwitterionic nanodrug delivery vector could be an ideal candidate for a safer tumor inhibition with a high efficacy than conventional synthetic polymer-based ones.

Polymers for Extrusion-Based 3D Printing of Pharmaceuticals: A Holistic Materials-Process Perspective

Three dimensional (3D) printing as an advanced manufacturing technology is progressing to be established in the pharmaceutical industry to overcome the traditional manufacturing regime of 'one size fits for all'. Using 3D printing, it is possible to design and develop complex dosage forms that can be suitable for tuning drug release. Polymers are the key materials that are necessary for 3D printing. Among all 3D printing processes, extrusion-based (both fused deposition modeling (FDM) and pressure-assisted microsyringe (PAM)) 3D printing is well researched for pharmaceutical manufacturing. It is important to understand which polymers are suitable for extrusion-based 3D printing of pharmaceuticals and how their properties, as well as the behavior of polymer-active pharmaceutical ingredient (API) combinations, impact the printing process. Especially, understanding the rheology of the polymer and API-polymer mixtures is necessary for successful 3D printing of dosage forms or printed structures. This review has summarized a holistic materials-process perspective for polymers on extrusion-based 3D printing. The main focus herein will be both FDM and PAM 3D printing processes. It elaborates the discussion on the comparison of 3D printing with the traditional direct compression process, the necessity of rheology, and the characterization techniques required for the printed structure, drug, and excipients. The current technological challenges, regulatory aspects, and the direction toward which the technology is moving, especially for personalized pharmaceuticals and multi-drug printing, are also briefly discussed.

One-step synthesis of iron oxide polypyrrole nanoparticles encapsulating ketoprofen as model of hydrophobic drug

This study reports a novel one-step synthesis of hybrid iron oxide/polypyrrole multifunctional nanoparticles encapsulating hydrophobic drug and decorated with polyethylene glycol. The overall process is based on the in situ chemical oxidative polymerization of pyrrole along with the reduction of ferric chloride (FeCl3) in the presence of ketoprofen as model drug and PEGylated surfactants. The final product is a nanocomposite composed of polypyrrole and a mixture of FeO/Fe2O3. Different concentrations of ketoprofen were encapsulated in the nanocomposite, and were characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Encapsulation efficiency of the final product was measured by absorption, which can reach up to 98%. The release experiments confirmed complete drug release after about 3h in PBS solution. Morphological characterization of the nanocomposites was performed by electron microscopy (scanning and transmission electron microscopy) which confirmed the spherical geometry and opaque nature of nanoparticles with average particle size well below 50 nm. The final product is multifunctional system, which could act both as a nanocarrier for drug molecules as well as a contrasting agent. Magnetic relaxometry studies confirmed their possible applications as potential contrast agent in the field of magnetic resonance imaging (MRI).

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.

Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier

In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC) with hyperbranched polycarbonsilane (HBPCSi) and β-cyclodextrin (β-CD) moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core–shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents.

Imaging of doxorubicin release from theranostic macromolecular prodrugs via fluorescence resonance energy transfer

Herein we present a FRET-based theranostic macromolecular prodrug (TMP) composed of (a) dendritic polyglycerol (PG) as polymeric nanocarrier, (b) doxorubicin (Dox) linked via a pH-sensitive hydrazone to (c) a tri-functional linker, and (d) an indodicarbocyanine dye (IDCC) attached in close proximity to Dox. The drug fluorescence is quenched via intramolecular FRET until the pH-sensitive hydrazone bond between the TMP and Dox is cleaved at acidic pH. By measuring its fluorescence, we characterized the TMP cleavage kinetics at different pH values in vitro. The intracellular release of Dox from the carrier was monitored in real time in intact cancer cells, giving more insight into the mode of action of a polymer drug conjugate.

Conjugated polymer nanoparticles for drug delivery and imaging

We prepared a new conjugated polymer nanoparticle with the size of about 50 nm that is prepared by electrostatic assembly of cationic conjugated polymer PFO and anionic poly(l-glutamic acid) conjugated with anticancer drug doxorubicin (PFO/PG-Dox). The PFO exhibits good fluorescence quantum yield, photostability, and little cytotoxicity to meet the essential requests for cell imaging. In PFO/PG-Dox nanoparticles, the fluorescence of PFO is highly quenched by Dox by electron transfer mechanism, and thus the PFO is in the fluorescence "turn-off' state. After PFO/PG-Dox nanoparticles are exposed to carboxypeptidase or are taken up by cancer cells, the poly(l-glutamic acid) is hydrolysed to release the Dox, inducing the activation of PFO fluorescence to "turn-on" state. This multifunctional nanoparticle system can deliver Dox to targeted cancer cells and monitor the Dox release based on fluorescence "turn-on" signal of PFO, which concurrently images the cancer cells. The present work opens the door for new functional studies of conjugated polymer in simultaneous imaging and disease therapeutics.

Design and development of polymer conjugates as anti-angiogenic agents

Angiogenesis, the formation of new blood vessels from pre-existing vasculature, is one of the central key steps in tumor progression and metastasis. Consequently, it became an important target in cancer therapy, making novel angiogenesis inhibitors a new modality of anticancer agents. Although relative to conventional chemotherapy, anti-angiogenic agents display a safer toxicity profile, the vast majority of these agents are low-molecular-weight compounds exhibiting poor pharmacokinetic profile with short half-life in the bloodstream and high overall clearance rate. The "Polymer Therapeutics" field has significantly improved the therapeutic potential of low-molecular-weight drugs and proteins for cancer treatment. Drugs can be conjugated to polymeric carriers that can be either directly conjugated to targeting proteins or peptides or derivatized with adapters conjugated to a targeting moiety. This approach holds a significant promise for the development of new targeted anti-angiogenic therapies as well as for the optimization of existing anti-angiogenic drugs or polypeptides. Here we overview the innovative approach of targeting tumor angiogenesis using polymer therapeutics.

Polymer Therapeutics: Concepts and Applications

Polymer therapeutics encompass polymer-protein conjugates, drug-polymer conjugates, and supramolecular drug-delivery systems. Numerous polymer-protein conjugates with improved stability and pharmacokinetic properties have been developed, for example, by anchoring enzymes or biologically relevant proteins to polyethylene glycol components (PEGylation). Several polymer-protein conjugates have received market approval, for example the PEGylated form of adenosine deaminase. Coupling low-molecular-weight anticancer drugs to high-molecular-weight polymers through a cleavable linker is an effective method for improving the therapeutic index of clinically established agents, and the first candidates have been evaluated in clinical trials, including, N-(2-hydroxypropyl)methacrylamide conjugates of doxorubicin, camptothecin, paclitaxel, and platinum(II) complexes. Another class of polymer therapeutics are drug-delivery systems based on well-defined multivalent and dendritic polymers. These include polyanionic polymers for the inhibition of virus attachment, polycationic complexes with DNA or RNA (polyplexes), and dendritic core-shell architectures for the encapsulation of drugs. In this Review an overview of polymer therapeutics is presented with a focus on concepts and examples that characterize the salient features of the drug-delivery systems.