Pt(IV) Complexes in the Search for Novel Platinum Prodrugs with Promising Activity

The kinetically inert, six coordinated, octahedral Pt(IV) complexes are termed dual-, triple-, or multi-action prodrugs based on the nature of the axially substituted ligands. These ligands are either inert or biologically active, where the nature of these axial ligands provides additional stability, synergistic biological activity or cell-targeting ability. There are many literature reports from each of these classes, mentioning the varied nature of these axial ligands. The ligands comprise drug molecules such as chlorambucil, doxorubicin, valproic acid, ethacrynic acid, biologically active chalcone, coumarin, combretastatin, non-steroidal anti-inflammatory drugs (NSAIDs) and many more, potentiating the anti-proliferative profile or reducing the side effects associated with cisplatin therapy. The targeting and non-targeting nature of these moieties exert additive or synergistic effects on the anti-cancer activity of Pt(II) moieties. Herein, we discuss the effects of these axially oriented ligands and the changes in the non-leaving am(m)ine groups and in the leaving groups on the biological activity. In this review, we have presented the latest developments in the field of Pt(IV) complexes that display promising activity with a reduced resistance profile. We have discussed the structure activity relationship (SAR) and the effects of the ligands on the biological activity of Pt(IV) complexes with cisplatin, oxaliplatin, carboplatin and the Pt core other than approved drugs. This literature work will help researchers to get an idea about Pt(IV) complexes that have been classified based on the aspects of their biological activity.

Green synthesis of aminated hyaluronic acid-based silver nanoparticles on modified titanium dioxide surface: Influence of size and chemical composition on their biological properties

This is the first report on an efficient, "environmentally friendly" chemical reduction method for the synthesis of aminated hyaluronic acid-based silver nanoparticles on the modified surface of titanium dioxide nanoparticles aimed for biological applications. Silver nanoparticles exhibit well-known physical-chemical and optical properties appropriate for different biological applications. Modifying the nanoparticles leads to a change in their expected bioactivity. This represents an important topic for the current research. We have developed a novel aminated hyaluronic acid (HA-EDA)-based protocol to obtain silver nanoparticles, in which HA-EDA was used for the first time as a reducing and stabilizing agent. The effect of the size of silver nanoparticles on the titanium dioxide surface and the chemical composition of the obtained materials were investigated by TEM, XRD, XPS, ATR-FTIR, Raman spectroscopy, NMR and H2-TPR analyses. The antioxidant, in vitro biocompatibility, and antimicrobial activity of the fabricated composites have been evaluated. The results prove that the prepared materials exhibit antimicrobial, antioxidant, and anti-inflammatory activity, thus providing protection against infection and supporting tissue regeneration, these two key effects being of paramount importance for promoting wound healing.

Recent developments in natural biopolymer based drug delivery systems

Targeted delivery of drug molecules to diseased sites is a great challenge in pharmaceutical and biomedical sciences. Fabrication of drug delivery systems (DDS) to target and/or diagnose sick cells is an effective means to achieve good therapeutic results along with a minimal toxicological impact on healthy cells. Biopolymers are becoming an important class of materials owing to their biodegradability, good compatibility, non-toxicity, non-immunogenicity, and long blood circulation time and high drug loading ratio for both macros as well as micro-sized drug molecules. This review summarizes the recent trends in biopolymer-based DDS, forecasting their broad future clinical applications. Cellulose chitosan, starch, silk fibroins, collagen, albumin, gelatin, alginate, agar, proteins and peptides have shown potential applications in DDS. A range of synthetic techniques have been reported to design the DDS and are discussed in the current study which is being successfully employed in ocular, dental, transdermal and intranasal delivery systems. Different formulations of DDS are also overviewed in this review article along with synthesis techniques employed for designing the DDS. The possibility of these biopolymer applications points to a new route for creating unique DDS with enhanced therapeutic qualities for scaling up creative formulations up to the clinical level.

CuS Nanoparticles-Loaded and Cisplatin Prodrug Conjugated Fe(III)-MOFs for MRI-Guided Combination of Chemotherapy and NIR-II Photothermal Therapy

Ovarian cancer has become an urgent threat to global female healthcare. Cisplatin, as the traditional chemotherapeutic agent against ovarian cancer, retains several limitations, such as drug resistance and dose-limiting toxicity. In order to solve the above problems and promote the therapeutic effect of chemotherapy, combining chemotherapy and phototherapy has aroused wide interest. In this study, we constructed a versatile cisplatin prodrug-conjugated therapeutic platform based on ultrasmall CuS-modified Fe(III)-metal-organic frameworks (MIL-88) (named M-Pt/PEG-CuS) for tumor-specific enhanced synergistic chemo-/phototherapy. After intravenous injection, M-Pt/PEG-CuS presented obvious accumulation in tumor and Fe(III)-MOFs possessed magnetic resonance imaging (MRI) to guide synergy therapy. Both in vitro and in vivo experimental results showed that M-Pt/PEG-CuS could not only successfully inhibit tumor growth by combining chemotherapy and NIR-II PTT but also avoid the generation of liver damage by the direct treatment of cisplatin(II). Our work presented the development of the nanoplatform as a novel NIR-II photothermal agent, as well as gave a unique combined chemo-photothermal therapy strategy, which might provide new ways of ovarian cancer therapy for clinical translation.

Polypseudorotaxane and polydopamine linkage-based hyaluronic acid hydrogel network with a single syringe injection for sustained drug delivery

Polypseudorotaxane structure and polydopamine bond-based crosslinked hyaluronic acid (HA) hydrogels including donepezil-loaded microspheres were developed for subcutaneous injection. Both dopamine and polyethylene glycol (PEG) were covalently bonded to the HA polymer for catechol polymerization and inclusion complexation with alpha-cyclodextrin (α-CD), respectively. A PEG chain of HA-dopamine-PEG (HD-PEG) conjugate was threaded with α-CD to make a polypseudorotaxane structure and its pH was adjusted to 8.5 for dopamine polymerization. Poly(lactic-co-glycolic acid) (PLGA)/donepezil microsphere (PDM) was embedded into the HD-PEG network for its sustained release. The HD-PEG/α-CD/PDM 8.5 hydrogel system exhibited an immediate gelation pattern, injectability through single syringe, self-healing ability, and shear-thinning behavior. Donepezil was released from the HD-PEG/α-CD/PDM 8.5 hydrogel in a sustained pattern. Following subcutaneous injection, the weight of excised HD-PEG/α-CD/PDM 8.5 hydrogel was higher than the other groups on day 14. These findings support the clinical feasibility of the HD-PEG/α-CD/PDM 8.5 hydrogel for subcutaneous injection.

Efficient Surface Immobilization of Chemically Modified Hyaluronans for Enhanced Bioactivity and Survival of In Vitro-Cultured Embryonic Salivary Gland Mesenchymal Cells

Embryonic salivary gland mesenchyme (eSGM) secretes various growth factors (bioactives) that support the proper growth and differentiation of salivary gland epithelium. Therefore, eSGM cells can be used as feeder cells for in vitro-cultured artificial salivary gland if their survival and bioactivity are properly maintained. As eSGM is encapsulated in a hyaluronan (HA)-rich developmental milieu, we hypothesized that mimicking this environment in vitro via surface immobilization of HA might enhance survival and bioactivity of eSGM. In this study, various HA derivatives, conjugated with catechol (HA–CA), thiol (HA–SH), or amine (HA–EDA) moieties, respectively, were screened for their efficacy of culturing eSGM-derived feeder cells in vitro. Among these HA derivatives, HA–CA showed the highest surface coating efficiency and growth enhancement effect on the embryonic submandibular gland. In addition, the HA–CA coating enhanced the production of growth factors EGF and FGF7, but not FGF10. These effects were maintained when eSGM cells isolated from the embryonic salivary gland were re-seeded to develop the feeder layer cells. CD44s (a major HA receptor) in eSGM cells were clustered at the cell membrane, and enhanced EGF expression was detected only in CD44 cluster-positive cells, suggesting that membrane clustering of CD44 is the key mechanism for the increased expression of EGF.

EGFR Targeted Cetuximab-Valine-Citrulline (vc)-Doxorubicin Immunoconjugates- Loaded Bovine Serum Albumin (BSA) Nanoparticles for Colorectal Tumor Therapy

Background

Specific modifications to carriers to achieve targeted delivery of chemotherapeutics into malignant tissues are a critical point for efficient diagnosis and therapy. In this case, bovine serum albumin (BSA) was conjugated with cetuximab–valine–citrulline (vc)–doxorubicin (DOX) to target epidermal growth factor receptor (EGFR) and enable the release of drug in EGFR-overexpressed tumor cells.

Methods

Maleimidocaproyl–valine–citrulline–p-aminobenzylcarbonyl-p-nitrophenol (MC-Val-Cit-PAB-PNP) and DOX were used to synthesize MC-Val-Cit-PAB-DOX, which was further linked with cetuximab to prepare antibody–drug conjugates (ADCs). Then, the ADCs were adsorbed to the surface of the BSA nanoparticles (NPs), which were prepared by a desolvation method to obtain cetuximab-vc-DOX-BSA-NPs. The cetuximab-vc-DOX conjugates adsorbed on the surface of the BSA nanoparticles were determined and optimized by size exclusion chromatography. An in vitro cytotoxicity study was conducted using a colon carcinoma cell line with different EGFR-expression levels to test the selectivity of cetuximab-vc-DOX-NPs.

Results

The vc-DOX and cetuximab-vc-DOX conjugates were both synthesized successfully and their structural characteristics confirmed by ¹H-NMR and SDS-PAGE. The MTT assay showed stronger cytotoxicity of cetuximab-vc-DOX-NPs versus control IgG-vc-DOX-NPs in EGFR–overexpressing RKO cells. Cellular binding and intracellular accumulation determined by flow cytometry and confocal laser scanning microscopy revealed the strong binding ability of cetuximab-vc-DOX-NPs to RKO cells. The in vivo imaging study demonstrated that cetuximab-vc-DOX-NPs exhibited higher fluorescent intensity in tumor tissues than non-decorated nanoparticles (IgG-vc-DOX-NPs). In vivo tumor inhibition and survival tests showed that cetuximab-vc-DOX-NPs revealed higher tumor inhibition efficacy and lower systemic toxicity than control IgG-vc-DOX- NPs

Conclusion

The obtained results emphasize that cetuximab-vc-DOX-NPs, with good tumor-targeting ability and low systemic toxicity, are a promising targeting system for drug delivery.

PEGylated nano-graphene oxide as a nanocarrier for delivering mixed anticancer drugs to improve anticancer activity

Due to their high specific surface area, graphene oxide and graphene oxide-base nanoparticles have great potential both in dual-drug delivery and combination chemotherapy. Herein, we developed cisplatin (Pt) and doxorubicin (DOX) dual-drug-loaded PEGylated nano-graphene oxide (pGO) to facilitate combined chemotherapy in one system. In this study, nano-sized pGO-Pt/DOX ranged around 161.50 nm was fabricated and characterized using zeta-potential, AFM, TEM, Raman, UV-Vis, and FTIR analyses. The drug delivery efficacy of Pt was enhanced through the introduction of pGO, and the final weight ratio of DOX: Pt: pGO was optimized to 0.376: 0.376: 1. In vitro studies revealed that pGO-Pt/DOX nanoparticles could be effectively delivered into tumor cells, in which they induced prominent cell apoptosis and necrosis and exhibited higher growth inhibition than the single drug delivery system or free drugs. The pGO-Pt/DOX induced the most prominent cancer cell apoptosis and necrosis rate with 18.6%, which was observed almost 2 times higher than that of pGO-Pt or pGO-DOX groups. in the apoptosis and necrotic quadrants In vivo data confirmed that the pGO-Pt/DOX dual-drug delivery system attenuated the toxicity of Pt and DOX to normal organs compared to free drugs. The tumor inhibition data, histopathology observations, and immunohistochemical staining confirmed that the dual-drug delivery system presented a better anticancer effect than free drugs. These results clearly indicated that the pGO-Pt/DOX dual-drug delivery system provided the means for combination drug delivery in cancer treatment.

Pursuing Specific Chemotherapy of Orthotopic Breast Cancer with Lung Metastasis from Docking Nanoparticles Driven by Bioinspired Exosomes

Breast cancer develops from local tissue but is characterized by a distinct metastatic pattern involving regional lymph nodes and distant organs, which is the primary cause of high mortality in breast cancer patients. Herein, optimal docking nanoparticles (NPs) composed of a laurate-functionalized Pt(IV) prodrug (Pt(lau)), human serum albumin (HSA), and lecithin were predicted by computational modeling, prepared by nanoprecipitation, and validated by fluorescence spectroscopy. As macrophages have been reported to be preferentially recruited by breast cancer, Rex, the exosome spontaneously secreted by murine RAW 264.7 cells, was isolated to encapsulate the NPs. This high-performance delivery system, called NPs/Rex, possessed the desired physicochemical properties, enhanced colloidal stability, and redox-triggered release profile. Investigations of cytodynamics proved that NPs/Rex was internalized through multiple pathways, avoided entrapment by bilayers, and successfully platinized nucleic acids after bioreduction in the cytosol. Intracellular activation of Pt(lau) was confirmed by observing the characteristic effects of cisplatin on cell proliferation and the cell cycle following treatment with NPs/Rex. During in vivo application, the bioinspired Rex coating endowed docking NPs with prolonged blood circulation, smart organ tropism, and enhanced biocompatibility, as well as robust platinum (Pt) chemotherapy for breast cancer cells in orthotopic tumors of fat pads and metastatic nodules of lungs. Therefore, this favorable nanoplatform might provide valuable insight into the derivatization and development of Pt anticancer drugs used currently in the clinic.

Glutathione-Responsive Prodrug Nanoparticles for Effective Drug Delivery and Cancer Therapy

Spurred by recent progress in medicinal chemistry, numerous lead compounds have sprung up in the past few years, although the majority are hindered by hydrophobicity, which greatly challenges druggability. In an effort to assess the potential of platinum (Pt) candidates, the nanosizing approach to alter the pharmacology of hydrophobic Pt(IV) prodrugs in discovery and development settings is described. The construction of a self-assembled nanoparticle (NP) platform, composed of amphiphilic lipid-polyethylene glycol (PEG) for effective delivery of Pt(IV) prodrugs capable of resisting thiol-mediated detoxification through a glutathione (GSH)-exhausting effect, offers a promising route to synergistically improving safety and efficacy. After a systematic screening, the optimized NPs (referred to as P6 NPs) exhibited small particle size (99.3 nm), high Pt loading (11.24%), reliable dynamic stability (∼7 days), and rapid redox-triggered release (∼80% in 3 days). Subsequent experiments on cells support the emergence of P6 NPs as a highly effective means of transporting a lethal dose of cargo across cytomembranes through macropinocytosis. Upon reduction by cytoplasmic reductants, particularly GSH, P6 NPs under disintegration released sufficient active Pt(II) metabolites, which covalently bound to target DNA and induced significant apoptosis. The PEGylation endowed P6 NPs with in vivo longevity and tumor specificity, which were essential to successfully inhibiting the growth of cisplatin-sensitive and -resistant xenograft tumors, while effectively alleviating toxic side-effects associated with cisplatin. P6 NPs are, therefore, promising for overcoming the bottleneck in the development of Pt drugs for oncotherapy.

Stimuli-Responsive Therapeutic Metallodrugs

The success of platinum-based anticancer agents has motivated the exploration of novel metal-based drugs for several decades, whereas problems such as drug-resistance and systemic toxicity hampered their clinical applications and efficacy. Stimuli-responsiveness of some metal complexes offers a good opportunity for designing site-specific prodrugs to maximize the therapeutic efficacy and minimize the side effect of metallodrugs. This review presents a comprehensive and up-to-date overview on the therapeutic stimuli-responsive metallodrugs that have appeared in the past two decades, where stimuli such as redox, pH, enzyme, light, temperature, and so forth were involved. The compounds are classified into three major categories based on the nature of stimuli, that is, endo-stimuli-responsive metallodrugs, exo-stimuli-responsive metallodrugs, and dual-stimuli-responsive metallodrugs. Representative examples of each type are discussed in terms of structure, response mechanism, and potential medical applications. In the end, future opportunities and challenges in this field are tentatively proposed. With diverse metal complexes being introduced, the foci of this review are pointed to platinum and ruthenium complexes.

Redox-responsive micelles from disulfide bond-bridged hyaluronic acid-tocopherol succinate for the treatment of melanoma

Nanotechnology-based chemotherapy is efficient in cancer treatment due to the targeted delivery of small molecules via nano-carriers, which are usually regarded as "inert". However, nano-materials are more preferred as carriers since many cause synergistic anti-tumor effects along with the drug cargo. In this study, a "bioactive" tocopherol succinate (TOS) was grafted to hyaluronic acid (HA) via of disulfide bonds to obtain HA-ss-TOS conjugates which can assemble into nano-micelles but dissociate when exposed to reducing environments in vitro and in vivo. Moreover, paclitaxel-loaded HA-ss-TOS micelles (HA-ss-TOS-PTX) can be efficiently taken up by B16F10 cells overexpressing CD 44, thereafter exhibiting enhanced cytotoxicity. The in vivo imaging study here revealed much greater tumor accumulation of Dir-labeled HA-ss-TOS compared to the free Dir group. In vivo antitumor activities further ensured that the PTX-loaded HA-ss-TOS micelles provided superior antineoplastic responses versus PTX-loaded HA-TOS micelles and Taxol. Moreover, the subcellular dissociated TOS from HA-ss-TOS showed synergistic effects with PTX. These experimental results revealed that reduction-responsive PTX-loaded polymeric nano-micelles with multi-functional properties hold great potential for anti-tumor treatment and, thus, should be further studied.

Preparation and evaluation of celecoxib nanosuspensions for bioavailability enhancement

We prepare celecoxib nanosuspensions using TPGS as stabilizer via high speed shear as a pre-treatment step, followed by HPH method; and the solidification of fresh nanosuspension was carried out by freeze-drying.

Component-based biocompatibility and safety evaluation of polysorbate 80

Components in polysorbate 80 are separated and classified into nine groups, which are investigated on their purity, safety and biocompatibility.

Exenatide loaded PLGA microspheres for long-acting antidiabetic therapy: preparation, characterization, pharmacokinetics and pharmacodynamics

We herein fabricated the exenatide-loaded microspheres by a water in oil in oil (W/O/O) method, which presented great effect on glycemic control with low initial burst release and reduced risk of gastrointestinal intolerance and hypoglycemia.

Preparation and characterization of a dual-receptor mesoporous silica nanoparticle–hyaluronic acid–RGD peptide targeting drug delivery system

Novel mesoporous silica nanoparticles conjugated with hyaluronic acid and RGD peptide were developed for dual-receptor mediated targeting drug delivery.