Characterization of naproxen–polymer conjugates for drug-delivery

Intracluster Sulphur Dioxide Oxidation by Sodium Chlorite Anions: A Mass Spectrometric Study

The reactivity of [NaL·ClO₂]⁻ cluster anions (L = ClO_x⁻; x = 0–3) with sulphur dioxide has been investigated in the gas phase by ion–molecule reaction experiments (IMR) performed in an in-house modified Ion Trap mass spectrometer (IT-MS). The kinetic analysis revealed that SO₂ is efficiently oxidised by oxygen-atom (OAT), oxygen-ion (OIT) and double oxygen transfer (DOT) reactions. The main difference from the previously investigated free reactive ClO₂⁻ is the occurrence of intracluster OIT and DOT processes, which are mediated by the different ligands of the chlorite anion. This gas-phase study highlights the importance of studying the intrinsic properties of simple reacting species, with the aim of elucidating the elementary steps of complex processes occurring in solution, such as the oxidation of sulphur dioxide.

Cysteine-Modified Self-Assembling Peptides on Gold: The Role of the Head and Tail

Molecular self-assembly consists of the spontaneous aggregation of molecules into a well-defined structure guided by noncovalent bonds. The self-assembly strategy is ubiquitous in nature and recently has been proposed as a nature-mimetic strategy in polymer science and biomaterial engineering. In this context, we aim at designing and testing innovative but simple chemical strategies to efficiently modify surfaces by exploiting minor modifications in the bioactive molecule functionalities, for example, introducing cysteine (Cys) as a terminal residue in self-assembling peptides (SAPs). In this work, we report the attenuated total reflection-Fourier transform infrared spectroscopy, synchrotron radiation-induced X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and time-of-flight secondary ion mass spectrometry investigation of self-assembled layers of oligopeptides anchored onto gold surfaces through cysteine residues, opportunely inserted in an SAP (EAK16-II) main chain in three different positions: at the amine end group, at the carboxyl end group, and at both terminal groups (i.e., a bidentate SAP). This study, which allowed us to individuate in the bidentate SAP the best candidate for the controlled production of ordered SAP layers on the gold substrate surface, is envisaged to open wide perspectives for efficient chemical modification of surfaces with biomolecules, leading to obtaining innovative bioactive materials for applications in the field of tissue engineering.

Core/shell nanoassembly of amphiphilic naproxen-polyethylene glycol: synthesis, characterisation and evaluation as drug delivery system

Small molecule-based amphiphiles self-assemble into nanostructures (micelles) in aqueous medium which are currently being explored as novel drug delivery systems. Here, naproxen-polyethylene glycol (N-PEG), a small molecule-derived amphiphile, has been synthesised, characterised and evaluated as hydrophobic drug carrier. ¹H, ¹³C Nuclear magnetic resonance (NMR), mass spectrometry (MS) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of N-PEG and dynamic light scattering (DLS) revealed the formation of nano-sized structures of ∼228 nm. Transmission electron microscope (TEM) analysis showed aggregation behaviour of the structures with average size of ∼230 nm. Biodegradability aspect of the micellar-structured N-PEG was demonstrated by lipase-mediated degradation studies using DLS and TEM. High encapsulation efficiency followed by release in a sustained manner of a well-known anticancer drug, doxorubicin, demonstrated the feasibility of the new drug delivery system. These results advocate the promising potential of N-PEG micelles as efficient drug delivery system for specific delivery to cancerous cells in vitro and in vivo.

A Stability-Indicating RP-HPLC-UV Method for Determination and Chemical Hydrolysis Study of a Novel Naproxen Prodrug

A new naproxen amide prodrug was synthesized and spectrally characterized and a simple, precise, and accurate stability-indicating RP-HPLC method was developed and validated for determination and chemical hydrolysis study of the prodrug. Forced degradation studies were conducted as per the International Conference on Harmonization (ICH) guidelines to establish the stability-indicating power of the method. Separations were performed on a C18 column (150 × 4.6 mm i.d., 5 μm p.s.). The mobile phase consisted of acetonitrile and phosphate buffer pH 4.0 in the ratio 60 : 40. The flow rate and injection volume were 1.0 mL/min and 15 μL, respectively. The peaks were monitored at 272 nm. The average retention time is 5.136 min. The linearity of the method was investigated in the range of 10–50 μg/mL and r2 was found to be larger than 0.9987. The LOD and LOQ were found to be 1.853 and 5.615 μg/mL, respectively. Results indicated that the degradants are well resolved and separated from the prodrug. Hydrolysis kinetics studies were carried out in buffer solutions (pH 1.2, 5.5 and 7.4) to establish the fate of the prodrug. The half-lives in the respective buffers were 23.5, 262, and 334 hours indicating sufficient stability to attain the goal of oral delivery.

Emerging Multifunctional NIR Photothermal Therapy Systems Based on Polypyrrole Nanoparticles

Near-infrared (NIR)-light-triggered therapy platforms are now considered as a new and exciting possibility for clinical nanomedicine applications. As a promising photothermal agent, polypyrrole (PPy) nanoparticles have been extensively studied for the hyperthermia in cancer therapy due to their strong NIR light photothermal effect and excellent biocompatibility. However, the photothermal application of PPy based nanomaterials is still in its preliminary stage. Developing PPy based multifunctional nanomaterials for cancer treatment in vivo should be the future trend and object for cancer therapy. In this review, the synthesis of PPy nanoparticles and their NIR photothermal conversion performance were first discussed, followed by a summary of the recent progress in the design and implementation on the mulitifunctionalization of PPy or PPy based therapeutic platforms, as well as the introduction of their exciting biomedical applications based on the synergy between the photothermal conversion effect and other stimulative responsibilities.

Functionalization of poly(ε-caprolactone) surface with lactose-modified chitosan via alkaline hydrolysis: ToF-SIMS characterization

Functionalization of poly(ε-caprolactone) (PCL) was performed via hydrolysis and subsequent grafting of lactose-modified chitosan (chitlac) at two different degrees of derivatization (9% and 64%). Time of flight secondary ion mass spectrometry (ToF-SIMS) and multivariate analysis (principal component analysis) were successfully applied to the characterization of PCL surface chemistry, evidencing changes in the biopolymer surface following base-catalyzed hydrolysis treatment. ToF-SIMS analysis also confirmed positive EDC/NHS-catalyzed (EDC: N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide; NHS: N-hydroxysuccinimide) immobilization of chitlac onto activated PCL surface, with formation of amide bonds between PCL surface carboxyl groups and amine residues of chitlac. Yield of grafting reaction was also shown to be dependent upon the lactosilation degree of chitlac.