This paper describes the fabrication of polyelectrolyte microspheres using porous manganese carbonate as a sacrificial template for entrapped photosensitizer (PS) drugs for photodynamic therapy application. These particles were used as templates for polyelectrolyte layer-by-layer assembly (Lbl) of two oppositely charged polyelectrolytes: poly(styrene sulfonate) and poly(allylamine hydrochloride). When the polyelectrolyte multilayer shell was built around the MnCO3 core by the Lbl protocol and the core was extracted with acid solution and EDTA, the resultant assembly consisted of hollow polyelectrolyte spheres. Chloroaluminum phthalocyanine was chosen as the model drug to load into the hollow spheres. All the spectroscopic results presented showed excellent photophysical parameters of the studied drug. The fabrication of polyelectrolyte hollow spheres can be used as an optimal medium for a variety of bioactive materials, which can also be encapsulated by the proposed method.

The management of patients with ’field cancerization‘ of the oral mucosa, with multicentric foci of invasion, presents a considerable problem for the head and neck surgeon. Surgical resection of synchronous or metachronous primary squamous cell carcinomas, along with adjacent premalignant lesions, is likely to be associated with considerable mutilation. Photodynamic therapy (PDT) has been shown to be of value in the treatment of superficial tumours in the upper aerodigestive tract, with excellent healing of treated areas. This study reports the use of PDT to treat 11 patients with ’field cancerization‘ occurring in the oral cavity. Six patients had multiple primary cancers and five had single primary tumours. All had associated areas of leukoplakia. Each received Photofrin 2 mg/kg 48 hours prior to photoirradiation with 50–100 J/cm² red laser light by surface illumination. Six to eight weeks later treated areas in 10 of the 11 patients showed a complete response to PDT; one patient had areas of residual leukoplakia. Two patients developed further areas of leukoplakia or erythroplakia within 12 months but no patient has had evidence of recurrent invasive carcinoma in the treated areas. Longer term follow-up will be necessary to exclude further recurrence. It is concluded that PDT offers an effective repeatable treatment option, whether on its own or as an adjunct to local excision, for patients with ’field cancerization‘ of the oral cavity.