Understanding the Degradation of Core-Shell Nanogels Using Asymmetrical Flow Field Flow Fractionation

Nanogels are candidates for biomedical applications, and core-shell nanogels offer the potential to tune thermoresponsive behaviour with the capacity for extensive degradation. These properties were achieved by the combination of a core of poly(N-isopropylmethacrylamide) and a shell of poly(N-isopropylacrylamide), both crosslinked with the degradable crosslinker N,N'-bis(acryloyl)cystamine. In this work, the degradation behaviour of these nanogels was characterised using asymmetric flow field flow fractionation coupled with multi-angle and dynamic light scattering. By monitoring the degradation products of the nanogels in real-time, it was possible to identify three distinct stages of degradation: nanogel swelling, nanogel fragmentation, and nanogel fragment degradation. The results indicate that the core-shell nanogels degrade slower than their non-core-shell counterparts, possibly due to a higher degree of self-crosslinking reactions occurring in the shell. The majority of the degradation products had molecule weights below 10 kDa, which suggests that they may be cleared through the kidneys. This study provides important insights into the design and characterisation of degradable nanogels for biomedical applications, highlighting the need for accurate characterisation techniques to measure the potential biological impact of nanogel degradation products

Facile production of nanocomposites of carbon nanotubes and polycaprolactone with high aspect ratios with potential applications in drug delivery

Facile route to polymer carbon nanotube nanocomposites.</p

Dual-responsive degradable core-shell nanogels with tuneable aggregation behaviour

We report the synthesis of core–shell nanogels by sequential addition of thermoresponsive monomers; N-isopropylacrylamide (NIPAM) and N-isopropylmethacrylamide (NIPMAM). The aggregation behaviour of aqueous dispersions of these particles in the presence of salt can be tuned by varying the monomer ratio. The inclusion of degradable cross-linker bis(acryloyl)cystamine (BAC) allows the nanogels to degrade in the presence of reducing agent, with nanogels composed of a copolymer of the two monomers not showing the same high levels of degradation as the comparable core–shell particles. These levels of degradation were also seen with physiologically relevant reducing agent concentration at pH 7. Therefore, it is hoped that the aggregation of these nanogels will have applications in nanomedicine and beyond

Tuning HIV drug release from a nanogel-based in situ forming implant by changing nanogel size

This talk presents some new notions of the theory of complex algebraic curves which have appeared as algebraic tools in string theory (see [4] for more details). In a sense, we have materialized non-existed complex powers of invertible sheaves on algebraic curves introduced at the level of the Atiyah algebras of invertible sheaves by Beilinson and Schechtman [1]. The Atiyah algebra AL in the case of an invertible sheaf L over a complete complex algebraic curve X is just the sheaf of differential operators of order ≤ 1 on L. There takes place the exact sequence 0 → O → AL → T → 0, where O is the structural sheaf and T is the tangent sheaf of X. The diagra

Tuning HIV drug release from a nanogel-based in situ forming implant by changing nanogel size

HIV is a global public health threat and requires life-long, daily oral dosing to effectively treat. This pill burden often results in poor adherence to the medications. An injectable in situ forming implant with tuneable drug release kinetics would allow patients to replace some of their daily pills with a single infrequent injection. In this work, we investigate how the size of poly(N-isopropylacrylamide) (polyNIPAm) nanogels influences the long-acting release behaviour of the HIV drug lopinavir from an in situ forming implant. Four sizes of polyNIPAm nanogels were prepared with mean diameters of 65, 160, 310 and 450 nm as characterised by dynamic light scattering. These nanogels all displayed synergistic dual stimuli responsive behaviour by aggregating only upon heating above 31 °C at physiological ionic strength. Mixing the nanogels with solid drug nanoparticles (SDNs) of lopinavir and exposing this concentrated dispersion to physiological temperature and ionic strength resulted in the in situ formation of nanocomposite implants. Three different loadings of the SDNs (33, 50 and 66% w/w) with each of the nanogels were prepared. The drug release behaviour and stability of these nanocomposite implants were then assessed in vitro over 360 hours. All samples displayed a single phase of drug release and application of the Ritger–Peppas equation indicated Fickian diffusion. Nanocomposites with the lowest loading of SDNs (33%) showed a linear relationship between nanogel diameter and the dissolution constant. These results show an attractive method for tuning the release of lopinavir from in situ loading implants with high drug loadings