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As an antibiotic-free treatment, photodynamic therapy (PDT) is considered a promising alternative to antibiotic therapy for bacterial infections. However, the recalcitrant bacterial biofilm has manifested significant endurance to PDT, especially the gram-negative bacteria with the protective outer membrane. The ever-developing nanotechnology has provided new opportunities to overcome the biofilm infection. Here, we used silver nanoparticles as the auxiliary for PDT to implement a combined treatment against biofilms. A photosensitizer chlorin e6-modified polyethyleneimine was used as the ligands of silver nanoparticles. In the combined treatment, the silver and PDT exhibited a synergistic effect by mutually reinforcing each other. The surface plasma resonance of silver promotes the photodynamic effect to generate singlet oxygen, and the reactive oxygen can in turn stimulate the oxidative dissolution of the bactericidal Ag + . As a result, the combined treatment showed advanced antibacterial activity against both the Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Moreover, the Gram-negative E. coli, which is more susceptible to silver, becomes almost extinct even in the biofilm form. The therapy on mice with epidermal wound infection verified the high effectiveness of the nanocomposite. This research developed an efficient combined therapy for biofilm eradication, which strengthens the weakness of PDT in eliminating the Gram-negative bacteria, providing an alternative way to fight biofilm-related infections.

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This paper describes an improved morphological approach to remove baseline wander from neonatal electrocardiogram (ECG) signals, with particular emphasis on preserving the ST segment of the original signal. The algorithm consists of two stages of morphological processing. First, the QRS complex and impulsive noise component due to skeletal muscle contractions etc., are detected and removed from the input signal. Second, the corrected QT interval (QTc) and RR interval are used to determine a structuring element. With this structuring element, the same morphological operation as in the first stage is then applied to the QRS-removed signal to obtain and remove the baseline wander. The performance of the algorithm is evaluated with simulated and real ECGs. Compared with an existing morphological method, there is a substantial improvement, especially in reducing distortion of the baseline waveform within the PR and QT intervals.