Multi-screening of β-lactam antibiotics for β-lactamase resistance by means of a paper-based analytical device with a 4-(2-pyridylazo)resorcinol (PAR)–Hg2+ complex†
β-Lactam antibiotics are widely used for the treatment of bacterial infections; however, an increase in the number of antibiotic-resistant bacteria, which produce β-lactamases that inactivate β-lactam antibiotics, can lead to serious untreatable diseases. Thus, proper prescribing of antibiotics and the development of new antimicrobial agents with strong resistance to hydrolysis by β-lactamases can be a solution to reduce antibiotic resistance and treat various bacterial infections. Accordingly, simple and rapid methods for the screening of antibiotics that show β-lactamase resistance are required. Therefore, we designed a multi-channel microfluidic paper-based analytical device (μPAD) for colorimetric screening of β-lactam antibiotics for β-lactamase resistance; the μPAD, created by modifying paper with self-assembling organosilane and a 4-(2-pyridylazo)resorcinol (PAR)–Hg2+ complex, can screen β-lactam antibiotics for hydrolytic resistance to multiple β-lactamases at once. To demonstrate its suitability for this task, we confirmed the resistance of already studied β-lactam antibiotics—penicillin G, cloxacillin, and ceftazidime—toward different classes of β-lactamases (penicillinase, TEM-1, and CTX-M-1) using the μPAD. Based on ligand exchange between hydrolyzed β-lactam antibiotics and PAR in the PAR–Hg2+ complex, colorimetric detection of the relative susceptibilities of β-lactam antibiotics to a β-lactamase is possible even with the naked eye in only 10 minutes. The portable and equipment-free μPAD allows for simple multi-screening of diverse classes of β-lactam antibiotics for β-lactamase resistance.