Philip James Thomas Reardon

Visible Light-Driven Pure Water Splitting by a Nature-Inspired Organic Semiconductor-Based System

For the first time, it is demonstrated that the robust organic semiconductor g-C3N4 can be integrated into a nature-inspired water splitting system, analogous to PSII and PSI in natural photosynthesis. Two parallel systems have been developed for overall water splitting under visible light involving graphitic carbon nitride with two different metal oxides, BiVO4 and WO3. Consequently, both hydrogen and oxygen can be evolved in an ideal ratio of 2:1, and evolution rates in both systems have been found to be dependent on pH, redox mediator concentration, and mass ratio between the two photocatalysts, leading to a stable and reproducible H2 and O2 evolution rate at 36 and 18 μmol h(-1) g(-1) from water over 14 h. Our findings demonstrate g-C3N4 can serve as a multifunctional robust photocatalyst, which could also be used in other systems such as PEC cells or coupled solar cell systems.

Electrohydrodynamic encapsulation of cisplatin in poly (lactic-co-glycolic acid) nanoparticles for controlled drug delivery

Targeted delivery of potent, toxic chemotherapy drugs, such as cisplatin, is a significant area of research in cancer treatment. In this study, cisplatin was successfully encapsulated with high efficiency (>70%) in poly (lactic-co-glycolic acid) polymeric nanoparticles by using electrohydrodynamic atomization (EHDA) where applied voltage and solution flow rate as well as the concentration of cisplatin and polymer were varied to control the size of the particles. Thus, nanoparticles were produced with three different drug:polymer ratios (2.5, 5 and 10wt% cisplatin). It was shown that smaller nanoparticles were produced with 10wt% cisplatin. Furthermore, these demonstrated the best sustained release (smallest burst release). By fitting the experimental data with various kinetic models it was concluded that the release is dependent upon the particle morphology and the drug concentration. Thus, these particles have significant potential for cisplatin delivery with controlled dosage and release period that are crucial chemotherapy parameters.

Mimicking Hierarchical Complexity of the Osteochondral Interface Using Electrospun Silk–Bioactive Glass Composites

The anatomical complexity and slow regeneration capacity of hyaline cartilage at the osteochondral interface pose a great challenge in the repair of osteochondral defects (OCD). In this study, we utilized the processing feasibility offered by the sol derived 70S bioactive glass and silk fibroin (mulberry Bombyx mori and endemic Indian non-mulberry Antheraea assama), in fabricating a well-integrated, biomimetic scaffolding matrix with a coherent interface. Differences in surface properties such as wettability and amorphousness between the two silk groups resulted in profound variations in cell attachment and extracellular matrix protein deposition. Mechanical assessment showed that the biphasic composites exhibited both an elastic region pertinent for cartilage tissue and a stiff compression resistant region simulating the bone phase. In vitro biological studies revealed that the biphasic mats presented spatial confinement for the growth and maturation of both osteoblasts and chondrocytes, marked by increased alkaline phosphatase (ALP) activity, osteopontin (OPN), sulfated glycosaminoglycan (sGAG) and collagen secretion in the cocultured mats. The non-mulberry silk based biphasic composite mats performed better than their mulberry counterpart, as evidenced by enhanced expression levels of key cartilage and bone specific marker genes. Therefore, the developed biphasic scaffold show great promise for improving the current clinical strategies for osteochondral tissue repair.

Organosilica Nanoparticles with an Intrinsic Secondary Amine: An Efficient and Reusable Adsorbent for Dyes

Nanomaterials are promising tools in water remediation because of their large surface area and unique properties compared to bulky materials. We synthesized an organosilica nanoparticle (OSNP) and tuned its composition for anionic dye removal. The adsorption mechanisms are electrostatic attraction and hydrogen bonding between the amine on OSNP and the dye, and the surface charge of the OSNP can be tuned to adsorb either anionic or cationic dyes. Using phenol red as a model dye, we studied the effect of the amine group, pH, ionic strength, time, dye concentration, and nanomaterial mass on the adsorption. The theoretical maximum adsorption capacity was calculated to be 175.44 mg/g (0.47 mmol/g), which is higher than 67 out of 77 reported adsorbents. The experimental maximum adsorption capacity is around 201 mg/g (0.53 mmol/g). Furthermore, the nanoparticles are highly reusable and show stable dye removal and recovery efficiency over at least 10 cycles. In summary, the novel adsorbent system derived from the intrinsic amine group within the frame of OSNP are reusable and tunable for anionic or cationic dyes with high adsorption capacity and fast adsorption. These materials may also have utility in drug delivery or as a carrier for imaging agents.

Drug Delivery Strategies for Platinum-Based Chemotherapy

Few chemotherapeutics have had such an impact on cancer management as cis-diamminedichloridoplatinum(II) (CDDP), also known as cisplatin. The first member of the platinum-based drug family, CDDPs potent toxicity in disrupting DNA replication has led to its widespread use in multidrug therapies, with particular benefit in patients with testicular cancers. However, CDDP also produces significant side effects that limit the maximum systemic dose. Various strategies have been developed to address this challenge including encapsulation within micro- or nanocarriers and the use of external stimuli such as ultrasound to promote uptake and release. The aim of this review is to look at these strategies and recent scientific and clinical developments.

Dimensionally and compositionally controlled growth of calcium phosphate nanowires for bone tissue regeneration

Nanostructured biomaterials with controlled morphology and composition are of high interest for bone tissue regeneration. As resorbable and biocompatible materials for bone tissue engineering, calcium phosphate nanowires and nanoneedles with different aspect ratios and compositions have been first synthesized without the use of any toxic surfactants via an energy efficient microwave assisted process. Correlation between solvent composition, mixing methodology and reagent stoichiometric ratios was investigated with the aim of producing orientated growth and varied biphasic composition, resulting in dimensionally controlled growth of materials containing varying hydroxyapatite (HA)/monetite quantities. It was observed that the HA/monetite content and dimensionality could be manipulated by changing the initial ethanol (EtOH) volume in the H2O/EtOH solvent mixture. Three dimensional particles with minute amounts of HA were produced when a H2O/EtOH volumetric ratio of 20/80 was used. Conversely, high aspect ratio (ca. 54) nanowires containing ca. 38 wt% HA were obtained with a 60/40 H2O/EtOH volumetric ratio. Importantly, the quantity of HA in the high aspect ratio nanowires/needles was controlled by varying the stoichiometric ratio of the reactants, demonstrating that one-dimensional materials with close to 100% HA can be achieved when the Ca/P ratio is increased to 1.67. Additionally, significant correlation between the extent of orientated growth of the materials and the point of EtOH addition during the mixing method was observed. The findings highlight that solvent composition, reactant stoichiometric ratio and mixing procedure can be used in tandem to tailor the morphology and composition of calcium phosphate materials, which are of very high importance in developing excellent materials suitable for bone tissue regeneration.

Morphology controlled porous calcium phosphate nanoplates and nanorods with enhanced protein loading and release functionality.

Calcium phosphate nanoplates and nanorods with controllable pores and enhanced protein loading and tuneable release characteristics are first synthesized without the use of any toxic surfactants by an energy efficient microwave assisted chemical process, hence demonstrating their viability as a tool for controllable drug delivery in biomaterial systems.

Mesoporous calcium phosphate bionanomaterials with controlled morphology by an energy‐efficient microwave method

Abstract Calcium phosphate nanomaterials with controllable morphology and mesostructure were synthesized via a rapid and energy efficient microwave method. An increase in aspect ratio from nanoplates to nanorods was achieved by increasing the solvent chain length, accompanied by a subsequent about 23% increase in surface area and porosity. Control of mesoporosity was also achieved by varying the synthesis time and quantity of H2O in the reaction solvent. Comparative studies were carried out using conventional heating (CON) and room temperature co‐precipitation (RT) methods. It was found that microwave synthesis produces nanomaterials with about 50% higher yields, 7.5/1.7 times higher surface area and 3/5 times higher pore volume than RT/CON materials respectively, as well as having a lower distribution of particle size/shape (lower standard deviation values of their dimensions). Furthermore, in vitro protein loading tests of microwave synthesized mesoporous calcium phosphate materials showed an enhanced loading efficiency of bovine serum albumin (3–7 times), as compared with non‐mesostructured products from room temperature precipitation, in accordance with their larger surface area and porosity.

Ultrasound enhanced delivery of cisplatin loaded nanoparticles

Cisplatin forms the basis for many chemotherapy regimens, however the maximum permissible dose is limited by its systemic toxicity. Nanoencapsulation of drugs has been shown to reduce off-target side effects and can potentially improve treatment burden on patients. However, uptake of nanoformulations at tumor sites is minimal without some form of active delivery. We have developed a submicron, polymeric nanoparticle based on biocompatible and degradable poly(lactic-co-glycolic acid) (PLGA) capable of encapsulating cisplatin and which can be bound to the surface of a phospholipid coated microbubble. The acoustic behavior and stability of the resulting nanoparticle loaded microbubbles will be compared with those of unloaded microbubbles. Results will also be presented on the extravasation of particles in a tissue mimicking phantom using a novel long working distance confocal microscope that enables particle distributions to be measured in situ and in real time.