Does a sister's giving money to her needy brother count as zakat, and would she be considered sinful if she is unable to pay the zakat on this money after giving it to her brother?

Lending money to a brother is a great reward and immense recompense, for every loan is equivalent to a charity. Scholars have unanimously agreed on the recommendation for the lender to give a loan due to the immense reward it entails, as it alleviates a Muslim's distress and is a means of relieving distress on the Day of Resurrection. If the loan is to a brother, it combines charity and maintaining kinship ties, which multiplies the reward. As for zakat on the loaned money, it is obligatory upon the lender every Hijri year. It can be paid along with their own money, or its payment can be delayed until the money is collected, at which point zakat for past years would be paid. It is not necessary to borrow money to pay zakat.