Amino-functionalized poly(L-lactide) lamellar single crystals as a valuable substrate for delivery of HPV16-E7 tumor antigen in vaccine development

Abstract

Background Poly( l -lactide) (PLLA) is a biodegradable polymer currently used in many biomedical applications, including the production of resorbable surgical devices, porous scaffolds for tissue engineering, nanoparticles and microparticles for the controlled release of drugs or antigens. The surfaces of lamellar PLLA single crystals (PLLA sc ) were provided with amino groups by reaction with a multifunctional amine and used to adsorb an Escherichia coli -produced human papillomavirus (HPV)16-E7 protein to evaluate its possible use in antigen delivery for vaccine development. Methods PLLA single crystals were made to react with tetraethylenepentamine to obtain amino-functionalized PLLA single crystals (APLLA sc ). Pristine and amino-functionalized PLLA sc showed a two-dimensional microsized and one-dimensional nanosized lamellar morphology, with a lateral dimension of about 15–20 μm, a thickness of about 12 nm, and a surface specific area of about 130 m 2 /g. Both particles were characterized and loaded with HPV16-E7 before being administered to C57BL/6 mice for immunogenicity studies. The E7-specific humoral-mediated and cell-mediated immune response as well as tumor protective immunity were analyzed in mice challenged with TC-1 cancer cells. Results Pristine and amino-functionalized PLLA sc adsorbed similar amounts of E7 protein, but in protein-release experiments E7-PLLA sc released a higher amount of protein than E7-APLLA sc . When the complexes were dried for observation by scanning electron microscopy, both samples showed a compact layer, but E7-APLLA sc showed greater roughness than E7-PLLA sc . Immunization experiments in mice showed that E7-APLLA sc induced a stronger E7-specific immune response when compared with E7-PLLA sc . Immunoglobulin G isotyping and interferon gamma analysis suggested a mixed Th1/Th2 immune response in both E7-PLLA sc -immunized and E7-APLLA sc -immunized mice. However, only the mice receiving E7-APLLA sc were fully protected from TC-1 tumor growth after three doses of vaccine. Conclusion Our results show that APLLA single crystals improve the immunogenicity of HPV16-E7 and indicate that E7-APLLA sc could be used for development of an HPV16 therapeutic vaccine against HPV16-related tumors.

Fine fibrillar and rectangular/hexagonal ordered grains of poly(3-hexyl thiophene) and poly(ethylene glycol) developed by seeding technique

“…Scanning force microscopy (SFM) images of the surfaces of PEO crystals revealed oriented fibril-like growth with increasing annealing temperature [15]. Recently, polymer single crystals and highly ordered structures have been employed in distinct potential applications including programmable assembly of nanoparticles [16], mimicking the natural bone nanostructures [17], magnetically recyclable catalyst support [18][19][20][21][22], templates to synthesize nanoparticle clusters [23,24], substrates for anisotropic deposition of Au nanoparticles [25], utilizable in semiconductor microelectronics and solid-state [26,27], ultrathin film systems [28], delivery systems for human papilloma virus-associated tumors [29][30][31], nano/micromotors [32,33], and photovoltaic devices [34].…”

Synergistic effects of surface grafting with heparin and addition of poly(d,l‐lactide) microparticles on properties of poly(l‐lactide) single crystals scaffolds

“…After washing with p ‐xylene, PLLA sc were dispersed in ethanol. PLLA sc were aminolyized under moderate conditions than reported previously to keep their features. A total of 500 mg of PLLA sc was reacted with 3 mL of 3% (wt/vol) distilled TEPA solution in isopropanol for 3 min at 50 °C.…”

“…Alternatively, another recent efficient and facial approach involved the use of poly( l‐ lactide) single crystals (PLLA sc ) to fabricate scaffolds by compression/molding salt leaching technique in the absence of high temperature or solvents . The main advantages of PLLA sc are their nanosized lamellar morphology and high specific surface area (≈130 m 2 g −1 ) …”

“…PLLA is often used as a scaffolding material due to its eminent biocompatibility, tunable biodegradability, and mechanical stability . However, the surface hydrophobicity of PLLA and its degradation into acidic products could hinder its tissue engineering applications .…”

“…In particular, the polymer surface is immobilized with bioactive compounds to offer a proper interface for cells . Conventionally, polymer surface is endowed with reactive carboxylic or amino functional groups before the immobilization . Attaching the bioactive compounds to the surface via a spacer compound, to decrease the steric effects, is also an effective strategy .…”