Doxorubicin-Bound Hydroxyethyl Starch Conjugate Nanoparticles with pH/Redox Responsive Linkage for Enhancing Antitumor Therapy

Starch-based "smart" nanomicelles: Potential delivery systems for doxorubicin

Vesicular nanosystems are a cornerstone to the contemporary drug delivery paradigm owing to their ability to encapsulate a variety of drug molecules, which improves the overall pharmacokinetics and bioavailability of the cargo drug. These systems have proven potential in the delivery of hydrophobic chemotherapeutic "Doxorubicin" (DOX), which faces frequent challenge relating to its nonspecific interactions, dose-limiting toxicity (myelosuppression being the most common manifestation), and short half-life (distribution half-life of 5 min, terminal half-life of 20-48 h), which limit its overall clinical effectiveness. "Smart" nanomicelles with stimuli-responsive linkages take advantage of tumor microenvironment for deploying the cargo drug at the target site, which prevents nonspecific distribution and, hence, low toxicity. Similarly, those with stealth properties evade protein response, which triggers the immunogenic response. The nanomicelles co-loaded with magnetic nanoparticles provide additional utility such as contrast enhancement agents in theranostics. Overall, the starch-based nanomicelles prove to be an excellent delivery system for overcoming the limitations associated with the conventional DOX delivery regime.

Recent Advances in Biomedical Nanotechnology Related to Natural Products

Natural product processing via nanotechnology has opened the door to innovative and significant applications in medical fields. On one hand, plants-derived bioactive ingredients such as phenols, pentacyclic triterpenes and flavonoids exhibit significant pharmacological activities, on another hand, most of them are hydrophobic in nature, posing challenges to their use. To overcome this issue, nanoencapsulation technology is employed to encapsulate these lipophilic compounds and enhance their bioavailability. In this regard, various nano-sized vehicles, including degradable functional polymer organic compounds, mesoporous silicon or carbon materials, offer superior stability and retention for bioactive ingredients against decomposition and loss during delivery as well as sustained release. On the other hand, some naturally occurring polymers, lipids and even microorganisms, which constitute a significant portion of Earth's biomass, show promising potential for biomedical applications as well. Through nano-processing, these natural products can be developed into nano-delivery systems with desirable characteristics for encapsulation a wide range of bioactive components and therapeutic agents, facilitating in vivo drug transport. Beyond the presentation of the most recent nanoencapsulation and nano-processing advancements with formulations mainly based on natural products, this review emphasizes the importance of their physicochemical properties at the nanoscale and their potential in disease therapy.

Overcoming biological barriers by virus-like drug particles for drug delivery

Virus-like particles (VLPs) have natural structural antigens similar to those found in viruses, making them valuable in vaccine immunization. Furthermore, VLPs have demonstrated significant potential in drug delivery, and emerged as promising vectors for transporting chemical drug, genetic drug, peptide/protein, and even nanoparticle drug. With virus-like permeability and strong retention, they can effectively target specific organs, tissues or cells, facilitating efficient intracellular drug release. Further modifications allow VLPs to transfer across various physiological barriers, thus acting the purpose of efficient drug delivery and accurate therapy. This article provides an overview of VLPs, covering their structural classifications, deliverable drugs, potential physiological barriers in drug delivery, strategies for overcoming these barriers, and future prospects.

Doxorubicin Conjugates: An Efficient Approach for Enhanced Therapeutic Efficacy with Reduced Side Effects

Continuous drug delivery modification is the scientific approach and is a basic need for the efficient therapeutic efficacy of active drug molecules. Polymer-drug conjugates have long been a hallmark of the drug delivery sector, with various conjugates on the market or in clinical trials. Improved drug solubilization, extended blood circulation, decreased immunogenicity, controlled release behavior, and increased safety are the advantages of conjugating drugs to the polymeric carrier like polyethylene glycol (PEG). Polymer therapies have evolved over the last decade, resulting in polymer-drug conjugates with diverse topologies and chemical properties. Traditional nondegradable polymeric carriers like PEG and hydroxy propyl methacrylate have been clinically employed to fabricate polymer-drug conjugates. Still, functionalized polymer-drug conjugates are increasingly being used to increase localized drug delivery and ease of removal. Researchers have developed multifunctional carriers that can "see and treat" patients using medicinal and diagnostic chemicals. This review focused on the various conjugation approaches for attaching the doxorubicin to different polymers to achieve enhanced therapeutic efficacy, that is, increased bioavailability and reduced adverse effects.

Diselenide-triggered hydroxyethyl starch conjugate nanoparticles with cascade drug release properties for potentiating chemo-photodynamic therapy

A novel type of diselenide bond-bridged hydroxyethyl starch-doxorubicin conjugate, HES-SeSe-DOX, was synthesized via a specially designed multistep synthetic route. The optimally achieved HES-SeSe-DOX was further combined with photosensitizer, chlorin E6 (Ce6), to self-assemble into HES-SeSe-DOX/Ce6 nanoparticles (NPs) for potentiating chemo-photodynamic anti-tumor therapy via diselenide-triggered cascade actions. HES-SeSe-DOX/Ce6 NPs were observed to disintegrate through the cleavage or oxidation of diselenide-bridged linkages in response to the stimuli arising from glutathione (GSH), hydrogen peroxide and Ce6-induced singlet oxygen, respectively, as evidenced by the enlarged size with irregular shapes and cascade drug release. In vitro cell studies exhibited that HES-SeSe-DOX/Ce6 NPs in combination with laser irradiation effectively consumed intracellular GSH and promoted a large rise in levels of reactive oxygen species in tumor cells, actuating the disruption of intracellular redox balance and the enhanced chemo-photodynamic cytotoxicity against tumor cells. The in vivo investigations revealed that HES-SeSe-DOX/Ce6 NPs were inclined to accumulate in tumors with persistent fluorescence emission, inhibited tumor growth with high efficacy and had good safety. These findings demonstrate the potential of HES-SeSe-DOX/Ce6 NPs for use in chemo-photodynamic tumor therapy and suggest their viability for clinical translation.

Recent advances in pH/enzyme-responsive polysaccharide-small-molecule drug conjugates as nanotherapeutics

Now-a-days, the polysaccharides are extensively employed for the delivery of small-molecule drugs ascribed to their excellent biocompatibility, biodegradability and modifiability. An array of drug molecules is often chemically conjugated with different polysaccharides to augment their bio-performances. As compared to their therapeutic precursors, these conjugates could typically demonstrate an improved intrinsic solubility, stability, bioavailability and pharmacokinetic profiles of the drugs. In current years, various stimuli-responsive particularly pH and enzyme-sensitive linkers or pendants are also exploited to integrate the drug molecules into the polysaccharide backbone. The resulting conjugates could experience a rapid molecular conformational change upon exposure to the microenvironmental pH and enzyme changes of the diseased states, triggering the release of the bioactive cargos at the targeted sites and eventually minimize the systemic side effects. Herein, the recent advances in pH and enzyme -responsive polysaccharide-drug conjugates and their therapeutic benefits are systematically reviewed, following a brief description on the conjugation chemistry of the polysaccharides and drug molecules. The challenges and future perspectives of these conjugates are also precisely discussed.

Advanced Skin Antisepsis: Application of UVA-Cleavable Hydroxyethyl Starch Nanocapsules for Improved Eradication of Hair Follicle-Associated Microorganisms

Hair follicles constitute important drug delivery targets for skin antisepsis since they contain ≈25% of the skin microbiome. Nanoparticles are known to penetrate deeply into hair follicles. By massaging the skin, the follicular penetration process is enhanced based on a ratchet effect. Subsequently, an intrafollicular drug release can be initiated by various trigger mechanisms. Here, we present novel ultraviolet A (UVA)-responsive nanocapsules (NCs) with a size between 400 and 600 nm containing hydroxyethyl starch (HES) functionalized by an o-nitrobenzyl linker. A phase transfer into phosphate-buffered saline (PBS) and ethanol was carried out, during which an aggregation of the particles was observed by means of dynamic light scattering (DLS). The highest stabilization for the target medium ethanol as well as UVA-dependent release of ethanol from the HES-NCs was achieved by adding 0.1% betaine monohydrate. Furthermore, sufficient cytocompatibility of the HES-NCs was demonstrated. On ex vivo porcine ear skin, a strong UVA-induced release of the model drug sulforhodamine 101 (SR101) could be demonstrated after application of the NCs in cyclohexane using laser scanning microscopy. In a final experiment, a microbial reduction comparable to that of an ethanol control was demonstrated on ex vivo porcine ear skin using a novel UVA-LED lamp for triggering the release of ethanol from HES-NCs. Our study provides first indications that an advanced skin antisepsis based on the eradication of intrafollicular microorganisms could be achieved by the topical application of UVA-responsive NCs.

pH-Sensitive nanoparticles based on amphiphilic imidazole/cholesterol modified hydroxyethyl starch for tumor chemotherapy

pH-Responsive nanoparticles (NPs) have emerged as an effective antitumor drug delivery system, promoting the drugs accumulation in the tumor and selectively releasing drugs in tumoral acidic microenvironment. Herein, we developed a new amphiphilic modified hydroxyethyl starch (HES) based pH-sensitive nanocarrier of antitumor drug delivery. HES was first modified by hydrophilic imidazole and hydrophobic cholesterol to obtain an amphiphilic polymer (IHC). Then IHC can self-assemble to encapsulate doxorubicin (DOX) and form doxorubicin-loaded nanoparticles (DOX/IHC NPs), which displayed good stability for one week storage and acidic sensitive long-term sustained release of DOX. As a result, cancer cell endocytosed DOX/IHC NPs could continuously release doxorubicin into cytoplasm and nucleus to effectively kill cancer cells. Additionally, DOX/IHC NPs could be effectively enriched in the tumor tissue, showing enhanced tumor growth inhibition effect compared to free doxorubicin. Overall, our amphiphilic modified HES-based NPs possess a great potential as drug delivery system for cancer chemotherapy.