Inorganic theranostic nanoparticles for Tuberculous Meningitis

Tuberculous meningitis (TBM) is the most severe form of tuberculosis infection with very high mortality and accounts
for 2-5% of all tuberculosis (TB) cases among children and HIV-positive adults, causing permanent neurological
consequences and disability. There is an urgent clinical need to develop vehicles to deliver antimicrobials/antiinflammatories
directly inside the brain to treat and diagnose early stage TBM.
The PhD research project will focus on 4 tasks: (1) synthesis of theranostics nanoparticles (NPs) with controlled size
(<100 nm) for optimal BBB crossing. (2) Decoration of NPs with pH responsive polymer which allows NPs to be absorbed
and pass into the blood stream. (3) NPs physicochemical characterisation. (4) In vitro testing of NPs transcytosis
formulation.
Task 1: Synthesis of NPs. The PhD student will design and develop spherical (MSNs) and flower (MSNFs) shape
mesoporous silica NPs with controlled size (<100 nm) containing first line antibiotics for optimal BBB crossing. The silica
network will be obtained by a modified Stöber method. Different concentrations of therapeutic ions (Ce, and Fe - for
MRI imaging) will be incorporated into MSNs using a post grafting method.
Task 2: Decoration of NPs with pH responsive polymer. A double polymeric shell will be synthesised in order to
enable the oral administration of the new therapeutic NPs. MSNs/MSNFs will be decorated with pH responsive polymer
(Eudragit E100) which is soluble and swells at gastric pH (up to 5), allowing NPs to be absorbed and pass into the blood
stream. Moreover, a permeable pH independent polymer (Eudragit RL 100) will be used to decorate MSNs and MSNFs.
Eudragit RL 100 avoids drug release in the stomach and in the gut. COOH-MSNs and COOH-MSNFs will be
functionalised, using carbodiimide as coupling reagents, with the L-Dopa molecule that is shown to strongly improve
their BBB crossing.
Task 3: MSNs and MSNFs physicochemical characterisation. Ion release kinetics of the MSNs/MSNFs@CeO2-
Fe3O4 in different biological media will be performed by ICP-MS. The NPs will be characterised using a range of
techniques including TEM-EDX, NMR, DLS, SAXS/WAXS and BET and HPLC. The magnetic properties of the NPs will
be studied by using a SQUID magnetometer. XPS and EELS will be used to measure the oxidation state of the ceria in
different media.
Task 4: In vitro testing of MSNs/MSNFs@CeO2-Fe3O4 transcytosis formulations.
The most promising MSNs/MSNFs@CeO2-Fe3O4 systems will be selected for testing in vitro. Cell lines and primary
astrocytes, microglia, and neurons will be cultured with selected MSNs/MSNFs@CeO2-Fe3O4. The toxicity of the new
system to healthy neuronal (astrocyte, microglia, neurons) and infected THP-1 microglial cells will be tested by using
MTT and LDH assays. ROS production will also be measured and correlated to the oxidation state of the nanoceria.
Inflammation will be assayed by measuring cytokine release. The antibacterial properties of the NPs system will be
measured using a colony forming assay.
To investigate the ability of the MSNs/MSNFs@CeO2-Fe3O4 to cross the BBB and, if necessary, adjust the nano-drug
formulation, a convergence of multi-disciplinary in vitro studies, using monocultures and specialised, unique co-culture
models, of TBM, microglia and brain endothelial cell monolayers being developed at the Crick by Prof. Robert Wilkinson
transwell model of the TBM infected BBB will be used. In both the barrier and diseased cells, a range of cell and
molecular biological processes will be monitored, including nanocarrier drug efficacy, bioreactivity, particle uptake,
transformation, particle degradation/products of degradation, translocation, and function and BBB
permeability/disruption.