A lipid-based delivery platform for thermo-responsive delivery of teriparatide.

Teriparatide (and analogue peptides) are the only FDA approved anabolic treatments for osteoporosis. Current therapies are administered as a daily subcutaneous injection, which limits patient adherence and clinical efficacy. To achieve the desired anabolic effect, a controlled delivery system must ensure a pulsatile release profile over a prolonged period. Thermo-responsive formulations (e.g. liposomes) can undergo a temperature-related phase-transition which can allow active control of drug release. Herein, thermo-responsive liposomes were developed to permit control over teriparatide release rate through modulation of temperature. Entrapment of hydrophilic molecules, including peptides, within liposomes remains challenging due to the large volume of hydration. In this work, hydrophobic ion pairing was employed for the first time to enhance peptide entrapment within liposomes. The method resulted in a hydrophobic complex that achieved high teriparatide entrapment (>75 %) in sub-200 nm monodispersed liposomes. Hydrophobic ion pairing outperformed other entrapment approaches. Several liposomal formulations with transition temperatures between 38 and 50 °C were obtained by modulation of the phospholipid composition. In vitro assays demonstrated temperature-dependent release kinetics with faster rates of release observed at/above the transition temperature. The maintenance of biological activity of released teriparatide was demonstrated in a cell-based assay utilising the PTH1 receptor. Overall, this provides the first proof-of-concept of the suitability of thermo-responsive systems for pulsatile delivery of teriparatide and similar peptides.

Quaternary Ammonium Palmitoyl Glycol Chitosan (GCPQ) Loaded with Platinum-Based Anticancer Agents-A Novel Polymer Formulation for Anticancer Therapy.

Quaternary ammonium palmitoyl glycol chitosan (GCPQ) has already shown beneficial drug delivery properties and has been studied as a carrier for anticancer agents. Consequently, we synthesised cytotoxic platinum(IV) conjugates of cisplatin, carboplatin and oxaliplatin by coupling via amide bonds to five GCPQ polymers differing in their degree of palmitoylation and quaternisation. The conjugates were characterised by 1H and 195Pt NMR spectroscopy as well as inductively coupled plasma mass spectrometry (ICP-MS), the latter to determine the amount of platinum(IV) units per GCPQ polymer. Cytotoxicity was evaluated by the MTT assay in three human cancer cell lines (A549, non-small-cell lung carcinoma; CH1/PA-1, ovarian teratocarcinoma; SW480, colon adenocarcinoma). All conjugates displayed a high increase in their cytotoxic activity by factors of up to 286 times compared to their corresponding platinum(IV) complexes and mostly outperformed the respective platinum(II) counterparts by factors of up to 20 times, also taking into account the respective loading of platinum(IV) units per GCPQ polymer. Finally, a biodistribution experiment was performed with an oxaliplatin-based GCPQ conjugate in non-tumour-bearing BALB/c mice revealing an increased accumulation in lung tissue. These findings open promising opportunities for further tumouricidal activity studies especially focusing on lung tissue.

Ultrasmall-in-Nano: Why Size Matters.

Gold nanoparticles (AuNPs) are continuing to gain popularity in the field of nanotechnology. New methods are continuously being developed to tune the particles' physicochemical properties, resulting in control over their biological fate and applicability to in vivo diagnostics and therapy. This review focuses on the effects of varying particle size on optical properties, opsonization, cellular internalization, renal clearance, biodistribution, tumor accumulation, and toxicity. We review the common methods of synthesizing ultrasmall AuNPs, as well as the emerging constructs termed ultrasmall-in-nano-an approach which promises to provide the desirable properties from both ends of the AuNP size range. We review the various applications and outcomes of ultrasmall-in-nano constructs in vitro and in vivo.

Particulate levodopa nose-to-brain delivery targets dopamine to the brain with no plasma exposure.

Levodopa (L-DOPA) is an oral Parkinson's Disease drug that generates the active metabolite - dopamine (DA) in vivo. However, oral L-DOPA exhibits low oral bioavailability, limited brain uptake, peripheral DA-mediated side effects and its poor brain bioavailability can lead to long-term complications. Here we show that L-DOPA forms stable (for at least 5 months) 300 nm nanoparticles when encapsulated within N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ). A nano-in-microparticle GCPQ-L-DOPA formulation (D50 = 7.2 µm), prepared by spray-drying, was stable for one month when stored at room and refrigeration temperatures and was capable of producing the original GCPQ-L-DOPA nanoparticles upon aqueous reconstitution. Nasal administration of reconstituted GCPQ-L-DOPA nanoparticles to rats resulted in significantly higher DA levels in the brain (Cmax of 94 ng g-1 above baseline levels 2 h post-dosing) when compared to nasal administration of L-DOPA alone, with DA being undetectable in the brain with the latter. Furthermore, nasal GCPQ-L-DOPA resulted in higher levels of L-DOPA in the plasma (a 17-fold increase in the Cmax, when compared to L-DOPA alone) with DA undetectable in the plasma from both formulations. These data provide evidence of effective delivery of DA to the brain with the GCPQ-L-DOPA formulation.

Development of Bio-Functionalized, Raman Responsive, and Potentially Excretable Gold Nanoclusters.

Gold nanoparticles (AuNPs) are used experimentally for non-invasive in vivo Raman monitoring because they show a strong absorbance in the phototherapeutic window (650-850 nm), a feature that is accompanied by a particle size in excess of 100 nm. However, these AuNPs cannot be used clinically because they are likely to persist in mammalian systems and resist excretion. In this work, clustered ultrasmall (sub-5 nm) AuNP constructs for in vivo Raman diagnostic monitoring, which are also suitable for mammalian excretion, were synthesized and characterized. Sub-5 nm octadecyl amine (ODA)-coated AuNPs were clustered using a labile dithiol linker: ethylene glycol bis-mercaptoacetate (EGBMA). Upon clustering via a controlled reaction and finally coating with a polymeric amphiphile, a strong absorbance in the phototherapeutic window was demonstrated, thus showing the potential suitability of the construct for non-invasive in vivo detection and monitoring. The clusters, when labelled with a biphenyl-4-thiol (BPT) Raman tag, were shown to elicit a specific Raman response in plasma and to disaggregate back to sub-5 nm particles under physiological conditions (37 °C, 0.8 mM glutathione, pH 7.4). These data demonstrate the potential of these new AuNP clusters (Raman NanoTheranostics-RaNT) for in vivo applications while being in the excretable size window.

The influence of amphiphilic quaternary ammonium palmitoyl glycol chitosan (GCPQ) polymer composition on oil-loaded nanocapsule architecture.

HYPOTHESIS: Predicting the exact nature of the self-assembly of amphiphilic molecules into supramolecular structures is of utmost importance for a variety of applications, but this is a challenge for nanotechnology. The amphiphilic drug delivery polymer-N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ) self-assembles in aqueous media to form nanoparticles. EXPERIMENT: This work aimed to develop a systematic predictive mathematical model on the eventual nature of oil-loaded GCPQ-nanoparticles and to determine the main independent variables that affect their nanoarchitecture following self-assembly. GCPQ polymers were produced with varying degree of palmitoylation (DP, 5.7-23.8 mol%), degree of quaternization (DQ, 7.2-22.7 mol%), and molecular weight (MW, 11.2-44.2 kDa) and their critical hydrophilic-lipophilic balance (cHLB) optimized to produce oil-loaded nanocapsules. FINDINGS: Non-linear mathematical models (Particle size (nm) = 466.05 - 5.64DP - 6.52DQ + 0.13DQ2 - 0.03 MW2 - 14.48cHLB + 0.48cHLB2) were derived to predict the nanoparticle sizes (R2 = 0.998, R2adj = 0.995). Smaller nanoparticle sizes (148-157 nm) were obtained at high DP, DQ, and cHLB values, in which DP was the main independent variable responsible for nanoparticle size. Single or multiple-oil cores with small particles stabilizing polymer shells could be observed depending on the oil volume. Nanoparticle architectures, especially the nature of the oil-core(s), were driven by the DP, DQ, cHLB, and oil concentration. Here, we have developed a predictive model that may be applied to understand the nanoarchitecture of oil-loaded GCPQ-nanoparticles.