Preparation of Hollow Porous HAP Microspheres as Drug Delivery Vehicles

Hollow HAP microspheres in sub-millimeter size were prepared and investigated as a drug delivery vehicle. The LCB （lithium-calcium borate） glass microspheres, which were made through flame spray process, were chosen as precursor for hollow HAP microspheres. The LCB glass microspheres reacted with phosphate buffer （K2HPO4） solution for 5 days at 37 ℃. During the reaction the Ca-P-OH compound precipitated on the surface of LCB glass microspheres and formed porous shells. Then the microspheres turned to be hollow ones with the same diameter as the glass microspheres after LCB glass run out in the chemical reaction. After heat-treated at 600 ℃ for 4 h, the Ca-P-OH compound became HAP, thus the hollow HAP microspheres were produced. The mechanism of forming hollow HAP microspheres through the chemical reaction between phosphate buffer and LCB glass was confirmed by the XRD analysis. The microstructure characteristics of the hollow, porous microspheres were observed by SEM.

Rational design of oral drugs targeting mucosa delivery with gut organoid platforms

Effective oral drugs and vaccines require high delivery efficiency across the gastrointestinal epithelia and protection of medically effective payloads(i.e.,immunogens)against gastric damage.In this study,hollowed nanocarriers(NCs:silica nanospheres and gold nanocages)with poly-l-lysine(PLL)coating and mammalian orthoreovirus cell attachment proteinσ1 functionalization(NC-PLL-σ1)were explored as functional oral drug delivery vehicles(ODDVs).The transport of these ODDVs to mucosal lymphoid tissues could be facilitated by microfold cells(M-cells)mediated transcytosis(viaσ1-α2–3-linked sialic acids adherence)across gastrointestinal epithelia.PLL coating provided protection and slow-release of rhodamine 6 G(R6G),a model payload.The transport effectiveness of these ODDVs was tested on intestinal organoid monolayers in vitro.When compared with other experimental groups,the fully functionalized ODDV system(with PLL-σ1)demonstrated two significant advantages:a significantly higher transport efficiency(198%over blank control at 48 h);and protection of payloads which led to both better transport efficiency and extended-release of payloads(61%over uncoated carriers at 48 h).In addition,it was shown that the M cell presence in intestinal organoid monolayers(modulated by Rank L stimulation)was a determining factor on the transport efficiency of the ODDVs:more M-cells(induced by higher Rank L)in the organoid monolayers led to higher transport efficiency for ODDV-delivered model payload(R6G).The fully functionalized ODDVs showed great potential as effective oral delivery vehicles for drugs and vaccines.