{'fraction_non_alphanumeric': 0.03046594982078853, 'fraction_numerical': 0.010752688172043012, 'mean_word_length': 5.734939759036145, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
4.2 Applications of SPAAC and SPANC in Life Sciences

The bioorthogonal, strain-promoted azide–alkyne cycloaddition (SPAAC) and the strain-promoted alkyne–nitrone cycloaddition (SPANC) reactions have been used for conjugation with high affinity and specificity. In contrast to the cytotoxic copper-catalyzed cycloaddition, both SPAAC and SPANC are inert in biological environments. This chapter reviews the developments and applications of SPAAC and SPANC in life sciences reported since 2004, when Bertozzi et al. published the first bioorthogonal reaction.